Пособие для сварщиков - Республиканский институт

Пособие для сварщиков - Республиканский институт
ФЕДЕРАЛЬНОЕ АГЕНТСТВО ПО ОБРАЗОВАНИЮ
Государственное образовательное учреждение высшего профессионального образования
«ТОМСКИЙ ПОЛИТЕХНИЧЕСКИЙ УНИВЕРСИТЕТ»
ЮРГИНСКИЙ ТЕХНОЛОГИЧЕСКИЙ ИНСТИТУТ
С.В.Гричин
АНГЛИЙСКИЙ ДЛЯ СВАРЩИКОВ
Учебное пособие
Издательство ЮТИ ТПУ
Юрга 2007
УДК 811 (Англ.)
ББК 81 (Англ.)
Г 82
Гричин С.В.
Г 82 Английский для сварщиков: Учебное пособие. – Юрга: Изд-во
ЮТИ ТПУ, 2007. – 181 с.
Учебное пособие предназначено для студентов вузов,
обучающихся
по
специальности
150202
«Оборудование
и
технология сварочного производства» и нацелено на развитие
навыков устной речи и чтения литературы по специальности на
английском языке.
УДК 811
Рецензенты
Доктор педагогических наук, зав.кафедрой иностранных языков
КузГТУ Зникина Л.С.
Доктор
педагогических
наук,
директор
международного
информационного центра ТГПУ Федотова Е.Е.
Кандидат
технических
наук,
зав.кафедрой
сварочного
производства ЮТИ ТПУ Зернин Е.А.
© Юргинский технологический институт, 2007
© Оформление. Издательство ЮТИ ТПУ, 2007
2
CONTENTS
Введение (Preface)
4
PART 1. JOB DESCRIPTION AND WELDING EDUCATION
6
Text 1. Welding & Machine Trades
7
Text 2. What is Welding and what do Welders Do
9
Text 3. Welding Skills
12
Text 4 (Table). Welding Education and Consultation
Training Centre
16
Text 5. Taking the Plunge: A Guide to Starting
an Underwater Welding Career
21
PART 2. THE HISTORY OF WELDING
25
Text 1. Welding History - A Story of Harnessing Heat
26
Text 2. From the History of Welding
31
Text 3. Welding's Vital Part in Major
American Historical Events
35
PART 3. WELDING PROCESSES & EQUIPMENT
40
Text 1. Introduction to Welding Processes & Equipment
41
Text 2. Basic Principles of Welding
44
Text 3. Characteristics of the Principal Welding Processes
48
Master Chart of the Principal Welding Processes
49
Text 4. Alternative Types of Welding
52
PART 4. ARC AND GAS WELDING IN DETAIL
55
Text 1. Arc Welding
55
Text 2.Oxygas Cutting Equipment
67
Text 3. Oxy-Fuel Welding and Cutting
80
PART 5. MODERN DEVELOPMENTS
89
Text 1. Friction Stir Welding (FSW)
90
3
Text 2. New Welding Method for Aluminium
96
Text 3. Man-machine Communication for Multi-run Arc Welding
101
Text 4 .IT in Welding and Cutting for the Welding Engineer –
PC Programs and the Internet
105
Text 5. Moving Weld Management from the Desk to the Desktop
113
PART 6. ADVANCED TECHNOLOGIES
118
AND THE FUTURE OF WELDING
Text 1. Space-Age Welding: The Past, Present and Future
of Aerospace Join Processes
119
Text 2. What Is Orbital Welding
124
Text 3. Welding Forges into the Future
128
PART 7. HEALTH, SAFETY AND ACCIDENT
PREVENTION
137
Text 1. Health Risks of Welding Fume/Gases
138
Text 2. Safety and Scheduled Maintenance Protect
Your Welding Assets
143
APPENDIX 1. WELDING THEORY & APPLICATION DEFINITIONS
147
APPENDIX 2. КЛАССИФИКАЦИЯ ВИДОВ И СПОСОБОВ СВАРКИ
175
4
Введение
Данное
английскому
учебное
языку
пособие
рассчитано
студентов
высших
на
подготовку
учебных
по
заведений,
обучающихся по специальности 150202 «Оборудование и технология
сварочного производства». В пособие включены аутентичные тексты на
английском языке по основной сварочной тематике, снабженные
упражнениями и заданиями, направленными на развитие навыков
чтения,
реферирования
и
аннотирования
с
литературы
по
специальности, а также навыков ведения беседы на специальные темы.
Работа с материалом, представленным в пособии, поможет
студентам не только овладеть английской технической терминологией
из области сварки и сварочных процессов, но и
познакомиться с
историей и современным состоянием отрасли, заглянуть в будущее
технологии.
Пособие снабжено иллюстративным и справочным материалами и
может использоваться как для аудиторной, так и для самостоятельной
работы студентов.
5
PART 1. JOB DESCRIPTION AND WELDING EDUCATION
Lead-in
In the list below tick the places where welders are
some more places to the list.
- machine-building factory workshop;
- bridge construction site;
- hospital;
- university department;
- shipyard;
- bank;
- repair shop;
- assembly site;
- bakery.
not likely to work. Add
Vocabulary
weld
repair and maintenance
sheet metal work
hobbyist
carpenter
ironworker
glazier
tender
supervisor
contractor
repair shop
stoop
awkward
machine setting
nondestructive testing
сварной шов, сварка, сваривать(ся)
ремонт оборудования и уход за ним
1) обработка листового металла 2) изделие из
листового металла 3) жестяницкие работы
человек, увлеченный своим хобби
плотник, столяр
металлург
стекольщик
1) лицо, присматривающее за кем-л.,
обслуживающее кого-л., что-л. 2) механик,
оператор
контролер
подрядчик, контрактор
ремонтная мастерская
наклоняться, нагибаться
неудобный; затруднительный, неловкий
1) наладка [настройка] станка
1) неразрушающие испытания;
2) неразрушающий контроль
6
Reading
Pre-reading
Find the Russian equivalents for the words and word combinations in italics
in the text.
Text 1. Welding & Machine Trades
Welding is a skill used by many trades: sheet
metal workers, ironworkers, diesel mechanics,
boilermakers, carpenters, marine construction,
steamfitters, glaziers, repair and maintenance
personnel in applications ranging from the home
hobbyist to heavy fabrication of bridges, ships and
many other projects. A variety of welding
processes are used to join units of metal. As a welder, you may work for
shipyards, manufacturers, contractors, federal, state, county, and city
governments, firms requiring maintenance mechanics, and repair shops.
Welding, while very physically demanding, can be very rewarding for
those who enjoy working with their hands. Welders need good eyesight,
manual dexterity and hand-eye coordination. They should also be able to
concentrate for long periods of time on very detailed work, as well as be in
good enough physical shape to bend and stoop, often holding awkward
positions for long periods of time. Welders work in a variety of
environments, both indoors and out, using heat to melt and fuse separate
pieces of metal together. Training and skill levels can vary, with a few weeks
of school or on-the-job training for the lowest level job and several years of
school and experience for the more skilled welding positions.
Skilled welders often select and set up the welding equipment, execute
the weld, and then examine the welds in order to make sure they meet the
appropriate specifications. They may also be trained to work in a variety of
materials, such as plastic, titanium or aluminum. Those with less training
perform more routine tasks, such as the welds on jobs that have already been
laid out, and are not able to work with as many different materials.
While the need for welders as a whole should continue to grow about
as fast as average, according the U.S. Bureau of Labor Statistics, the demand
for low-skilled welders should decrease dramatically, as many companies
7
move towards automation. However, this will be partially balanced out by
the fact that the demand for machine setters, operators and tenders should
increase. And more skilled welders on construction projects and equipment
repair should not be affected, as most of these jobs cannot be easily
automated. Because of the increased need for highly skilled welders, those
with formal training will have a much better chance of getting the position
they desire. For those considering to prepare themselves to a meaningful
welding-career, there are many options available.
There are also different professional specialties and levels, that should
be understood to make an informed choice. Some of these are: welder,
welding machine operator, welding technician, welding schedule developer,
welding procedure writer, testing laboratory technician, welding non
destructive testing inspector, welding supervisor, welding instructor,
welding engineer.
While-reading activity
Make a list of all the words in the text indicating:
a) welding professions and levels: welder, welding machine operator, …
b) trades where welding skill is used: …
c) places/fields a welder can work at (in): …
d) personal qualities a welder should have:
Answer the following questions on the text.
1. What are the trades where welding skills are used?
2. Where can welders work?
3. What personal characteristics should welders have?
4. How does the environment in which welders work vary?
5. What does it take to be s low-skilled/skilled welder?
6. What are welders able to do in terms of complexity of tasks and variety of
materials?
7. What are the job opportunities for low-skilled/skilled welders for the
nearest future as specified by the U.S. Bureau of Labor Statistics?
8. What are the advantages of having formal training for making a welding
career?
9. As you see, welding includes various professional specialties and levels.
What is yours?
After-reading activity
Translate the following sentences from Russian into English:
8
1. Сфера применения сварки охватывает большое количество областей
промышленности.
2. Профессия сварщика требует физической выносливости из-за частой
необходимости работы в нестационарных условиях.
3. Для того чтобы стать квалифицированным сварщиком, необходима
длительная теоретическая подготовка и практический опыт работы.
4. Квалифицированный сварщик должен сам уметь подбирать
необходимое сварочное оборудование, материалы и технику сварки.
5. Чем выше квалификация сварщика, тем больше количество
материалов, с которыми он может работать, и разнообразнее виды
выполняемых работ.
6. В настоящее время имеются большие возможности для освоения
профессии сварщика.
Look through the last paragraph of the text and say, what exactly, in your
opinion, the following welding specialists do:
welder
welding machine operator
welding technician
welding schedule developer
welding procedure writer
testing laboratory technician
welding non destructive testing
inspector
Writing
Write five sentences (one per each paragraph) summarizing the main ideas of
the text.
Reading
Skim the text to understand its main ideas
Text 2. What is welding and what do welders do?
Welding is the most economical and efficient way to join metals
permanently. It is the only way of joining two or more pieces of metal to
9
make them act as a single piece. Welding is vital to our economy. It is often
said that over 50% of the gross national product of the U.S.A. is related to
welding in one way or another. Welding ranks high among industrial
processes and involves more sciences and variables than those involved in
any other industrial process. There are many ways to make a weld and many
different kinds of welds. Some processes cause sparks and others do not even
require extra heat. Welding can be done anywhere…
outdoors or indoors, underwater and in outer space.
Nearly everything we use in our daily life is
welded or made by equipment that is welded. Welders
help build metal products from coffeepots to
skyscrapers. They help build space vehicles and millions
of other products ranging from oil drilling rigs to automobiles. In
construction, welders are virtually rebuilding the world, extending subways,
building bridges, and helping to improve the environment by building
pollution control devices. The use of welding is practically unlimited. There
is no lack of variety of the type of work that is done.
Welders are employed in many industry groups. Machinery manufacturers
are responsible for agricultural, construction, and mining
machinery. They are also involved in bulldozers, cranes,
material handling equipment, food-processing machinery,
papermaking and printing equipment, textiles, and office
machinery.
The fabricated metals products compiles another
group including manufacturers of pressure vessels, heat exchangers, tanks,
sheet metal, prefabricated metal buildings and architectural and ornamental
work. Transportation is divided into two major groups: manufacturers of
transportation equipment except motor vehicles; and motor vehicles and
equipment. The first includes shipbuilding, aircraft, spacecraft, and railroads.
The second includes automobiles, trucks, buses, trailers, and associated
equipment.
A small group of welders belongs to the group of
repair services. This includes maintenance and repair on
automobiles or refers to the welding performed on
industrial and electrical machinery to repair worn parts.
The mining, oil extraction, and gas extraction industries
form yet another group. A large portion of the work
involves drilling and extracting oil and gas or mining of ores, stone, sand and
gravel.
Welders are also employed in the primary metals industries to include
steel mills, iron and steel foundries, smelting and refining plants. Much of
10
this work is maintenance and repair of facilities and equipment. Another
group is the electrical and electronic equipment companies. Welding done by
this group runs from work on electric generators, battery chargers, to
household appliances.
Public administration employs welders to perform
maintenance welding that is done on utilities, bridges,
government armories and bases, etc. Yet another group
involves wholesale and retail establishments. These would
include auto and agricultural equipment dealerships, metal
service centers, and scrap yards.
Probably the smallest group of welders, but perhaps
those with the biggest impact on the public are the artist and
sculptors. The St. Louis Arch is possibly one of the best
known. But there are many other fountains and sculptures in
cities and neighborhoods around the world.
While-reading activity
Find the English equivalents for the following words and word combinations:
валовой национальный продукт, на открытом воздухе, в помещении,
космический корабль, горное оборудование.
True or false?
1. Welding is an important process employed by modern industry.
2. All welding processes are similar.
3. All welding processes require work pieces to be heated.
4. The smallest group of welders belongs to the group of repair services.
5. Welding is the only way to join metals.
After-reading activity
Make up a summary of the text using the following sentences as a
beginning:]
1. Welding is…. 2. Welding ranks… 3. There are many kinds… 4. Welding
can be made… 5. Welders can… 6. The use of welding is… 7. Welders are
employed in … .
Lead-in
11
You already know where welders are involved. Read the text below and find
out if there are more such places.
Vocabulary
journeyman (person)
apprentice
plate working
blueprint
brazing
GTA (gas tungsten
arc) welding
TIG (ungsten inert
gas welding)
SMAW (shielded
metal arc welding)
SAW (submerged arc
welding)
resistance welding
flux core
metal core
shift work
наемный квалифицированный рабочий
ученик
обработка листового металла
1) делать светокопию, копировать чертеж 2)
делать разметку
пайка твердым припоем (из меди и цинка)
сварка неплавящимся электродом
дуговая сварка вольфрамовым электродом в среде
инертного газа
дуговая сварка покрытым металлическим
электродом
(дуговая) сварка под флюсом
(контактная) сварка сопротивлением
флюсовая сердцевина ( порошковой проволоки )
металлический сердечник
(по)сменная работа, работа по сменам
Reading
Text 3. Welding Skills
A Welder permanently joins pieces of metal with metal filler, using heat
and/or pressure. Welders join parts being manufactured, they build structures
and repair broken or cracked parts, according to specifications.
Job Related Skills, Interests and Values
using and maintaining tools, material handling equipment and welding
equipment;
• reading and interpreting blueprints;
• acquiring thorough knowledge of arc, gas and resistance welding
theory ;
• laying out, cutting and forming metals to specifications;
• preparing the work site;
•
12
•
•
•
•
fitting sub-assemblies and assemblies together and preparing
assemblies for welding ;
welding using shielded metal arc welding, gas metal arc welding, gas
tungsten arc welding, flux core or metal core arc welding, submerged
arc welding and plasma arc welding processes;
carrying out special processes such as welding studs and brazing;
ensuring quality of product/process before, during and after welding;
What Preparation and Training Do You Need?
To become a Welder you should complete Grade 12 with credits in
mathematics (particularly technical math) and some shop courses. In Ontario,
welding is an unrestricted trade; completion of an apprenticeship could take
approximately 3 years including 3 periods of 8 weeks (720 hours) in-school
theory. Upon successful completion of the training agreement, you will
receive a Certificate of Apprenticeship.
What’s Your Future as a Welder?
Most workers in this occupation work full-time, sometimes in shift work,
usually indoors. Those with the ability to work with high-technology welding
applications may have better employment opportunities. The bulk of
employment opportunities are predicted to occur in the non-electrical,
machinery, construction and metal-fabricating industries. Some workers will
become self-employed. Examples of companies that employ welders include:
•
•
•
•
•
•
•
•
Fabricating shops;
Manufacturers of structural steel and platework;
Construction industries;
Boilers;
Heavy machinery contractors;
Aircraft contractors;
Ship building and other transportation contractors;
Specialized welding shops.
Wage Rate
•
•
as an apprentice you would start at a wage rate less than that of a
journeyperson
this rate increases gradually as you gain competency
13
•
the wage range for fully qualified welders according to the Peel Halton
Dufferin HRDC Wage Book is between $9.50/hr to $16.18/hr, with a
median salary of $12.50/hr.
After reading activity
Revise the information of Unit1 and make a list of the things welders should
be able to do and places they can work at.
Self-Rating
Ask Yourself: Is Working as a Welder For You?
Are you good at preparing and planning a job from start
to finish?
Yes
No
Can you look at a diagram or shop drawing and
visualize how things come together?
Yes
No
Do you like figuring out what’s wrong with something
and then repairing it?
Yes
No
Are you able to bend, stretch, kneel, stand for long
periods and lift material and supplies?
Yes
No
Would it bother you to work around dangerous gases
and intense heat?
Yes
No
Do you have good hand/eye coordination to guide a
welding arc along the edges of metal?
Yes
No
If you answered Yes to most of these questions, welder may be for you!
Lead-in
You already know what sort of skills you should have to be a welder. Now
think of the answers to the following questions:
1. How long should a person be trained to become a skilled welder?
2. Do you think that a welder should be able to use all kinds of welding?
3. What is more interesting to you personally: welding techniques, welding
inspection (other)?
14
Vocabulary
technique
case study
shielded metal arc
welding
arc welding
submerged arc
welding
oxyfuel
electric resistance
welding
tensile test
bending test
impact test
discontinuity
volumetric
hardness
tension
site welding
heat flow
heat treatment
welding metallurgy
hardenability
weldability
non-ferrous
filler metal
alloy
ASME
AWS
1) техника, способ, технические приемы 2) метод;
методика,
учебный пример; разбор конкретного случая
дуговая сварка покрытым металлическим
электродом
электродуговая сварка
дуговая сварка под флюсом
газоплазменный
(контактная) сварка сопротивлением
испытание на растяжение
испытание на изгиб
испытание на ударную вязкость
отсутствие непрерывности, нарушение
последовательности; несплошность
объемный
твердость, прочность; сопротивляемость
(механическим воздействиям)
натяжение; растяжение, растягивание, удлинение
монтажные сварочные работы
тепловой поток
термическая обработка
металлургия сварки
1) закаливаемость 2) прокаливаемость 3)
способность к закаливанию
свариваемость
цветной (о металле), не содержащий железа
присадочный металл
сплав
сокр. от American Society of Mechanical Engineers
Американское общество инженеров-механиков
сокр. от American Welding Society Американское
сварочное общество
Match the words from the list below with their definitions
a) alloy, b) joint, c) inspection, d) welding, e) laser, f) design, g) property, h)
course, j) plasma, k) arc.
15
1. To contrive, to formulate, to project, to draw, to plan, to sketch out;
2. Joining pieces of metal (or nonmetal) at faces rendered plastic or liquid by
heat or pressure (or both).
3. a) A junction or mode of joining parts together; b) the place where two
things are joined together
4. The luminous arc or bridge across a gap between two electrodes when an
electric current is sent through them.
5. a) A careful, narrow or critical examination or survey; b) an official
examination.
6. An instrument which amplifies light waves by stimulation to produce a
powerful, coherent beam of monochromatic light, an optical maser.
7. Metal blended with some other metallic or nonmetallic substance to give it
special qualities, such as resistance to corrosion, greater hardness, or tensile
strength.
8. A planned programme of study.
9. Peculiar or inherent quality.
10. A hot, ionized gas containing approximately equal numbers of positive
ions and electrons.
Reading and Speaking
Imagine you are a trying to choose a welding course to your needs. Which
one will you choose if your needs are like these:
1. You have to know how to carry out mechanical tests.
2. You are interested in welding ferrous alloys and non ferrous alloys.
3. You want to introduce computers in your welding process.
4. You are new to welding and would like to be introduced to basic welding
processes.
5. You want to learn how to choose the right type of welding for your
specific purposes.
6. You want to be a highly qualified and certified expert in the field of
welding.
7. You want to be familiar with welding standards
Use the table below to choose the course.
Text 5 (Table). Welding Education and Consultation Training Centre
Course
Welding
Course Objectives
The main objective of this
16
Course Outlines
Materials properties related to
Design
course is to introduce
welding engineers to the
subject of welding design.
Many factors have to be
considered in this issue.
These factors include:
consumer requirement,
technical specifications, and
environmental and
economical constrains
Welding
The main objective of this
Fundamentals course is to familiarize
engineers and inspectors to
various aspects related to
welding techniques,
inspection and quality
procedures in welding
industry. The course is
designed for engineers of
scientists with no or little
experience in the welding
field.
Welding
Inspection
Non
Destructive
testing
Certification:
welding. Welding process
selection. Types of welded
joints. Welding Accessibility
and Inspection. Economical
Analysis. Design information.
Welding symbols. Case
studies.
Welding processes: Shielded
metal Arc welding, Arc
welding, Gas tungsten Arc
welding, Submerged Arc
welding & Oxyfuel welding &
electric resistance. Cutting
processes: Oxygen cutting,
plasma cutting and laser
cutting. Inspection of
weldments: Nondestructive
testing of welments.
Mechanical testing of
weldments (tensile, bending,
impact).
Significance of weld
The course discusses both
qualification inspections and discontinuities. Welding
on-line inspections of
inspection (non-destrutive
welded joints. These include testing techniques: surface
mechanical tests (tension,
inspection, magnetic particle,
bending, impact, ...etc, and volumetric, radiography, and
non destructive tests.
ultrasonic). Destructive testing
techniques: hardness, tension,
bending, ...etc. The control of
quality during shop operations.
The control of quality during
site welding.
Level I: Is to train inspectors
to be able to pass level I
examination and to be able
to inspect using the chosen
17
Physical principals of test.
Processing. Test equipment
and materials. Codes,
standards, procedures and
Magnetic
Particle &
Liquid
Penetrant
Testing (MT
& PT)
technique. Level II: Is to
upgrade level I inspectors to
be able to pass level II
examination and to be able
to inspect, write a report, etc
in the chosen technique.
Welding
Metallurgy
The course delineates the
main changes in the
microstructure and/or the
morphology of the metals
and alloys during welding
that lead to changes in
properties. Alloys discussed
in the course include all
types of steels, Cast Iron,
Nickel, Copper alloys, ...etc
Welding
Quality
Assurance
For each application, the
welding process is
controlled by specific code
or standard. The course
includes discussions of
ASME boiler and pressure
vessel code AWS steel
structure code and other
standards.
Welding
Techniques
Selection of the welding
process is very important.
The course discusses the
variables of each welding
process and gives directions
for selecting the proper
18
safety. Test physical
principals. Equipment and
radiation source. Radiographic
recording. Work parameters
and conditions. Defectology.
Selection of techniques. Test
methods according to
standards. Personal safety and
protection.
Heat flow in welding. Effect
of pre-and-post weld heat
treatment. Introduction to
welding metallurgy
(hardenability and
weldability). Metallurgy of
steels. Welding of ferrous
alloys: Carbon-steels, Low
alloy steels, Stainless steels,
and Cast Iron. Welding of non
ferrous alloys: Al- Ni- and
Cu-alloys. Identification and
specifications of welding filler
metals. Case studies.
Welding co-ordination: tasks
& responsibility. Quality
requirements for welding.
Qualification of welding
procedures and welders.
International codes and
standards. Mechanical testing
of welds. Non-destructive
testing of welds. Documents
for weld quality assurance.
Case studies.
Overview of welding
techniques and processes.
Conventional techniques: arc,
Oxy fuel and resistance
welding. Non-conventional:
plasma, electron beam, laser
AWS
Certified
welding
Engineer
process for specific
application. Welding
processes discussed include:
SMAW, GMAW, GTAW,
etc.
welding. Flame and arc cutting
of metals. Computer
applications in welding. Case
studies.
The highest level of
certification in the field of
welding
To get certified as a welding
engineer you need to attend
four exams: Fundamentals of
science. Applied science.
Fundamentals of welding.
Applied welding.
Translate the following sentences into Russian:
1. Кислородная, плазменная и газовая резка изучаются в курсе «Основы
сварочного производства».
2. Методика проведения разрушающих испытаний изучается в курсе
«контролер сварочного участка» («приемщик сварочных изделий»).
3. К традиционным типам сварки относятся: электродуговая,
кислородно-газовая и контактная электросварка.
4. Каждый сварщик должен знать правила личной безопасности и
использовать индивидуальные средства (equipment) защиты, а также
разбираться в международных кодах и стандартах.
5. Во время сварки происходит изменение микроструктуры металла, что
приводит к изменению его свойств.
6. При проведении монтажных сварочных работ особенно важно
контролировать качество шва.
Writing
Write a short summary about a welder’s competence. Cover the following
areas:
- welding courses welders can take;
- types of welding welders should be able to use,
- testing techniques welders should know about.
Lead-in
Before you read, think of the following questions:
1. What does it mean to be a surface welder?
19
2. When does it become necessary to weld underwater?
3. Do you consider underwater welding an interesting career opportunity?
Vocabulary
plunge
take the plunge
commercial
subsea
rigging
fitter
alignment
beveling
stripping
patch
scuba diver
physical
(examination)
oxyfuel
draft
lapse
прыжок, ныряние, погружение (в воду или
другую среду)
сделать решительный шаг
1) коммерческий, торговый; 2) промышленный 3)
рентабельный, прибыльный Syn: profitable 4)
технический
погруженный в воду, подводный
1) оснастка, 2) сборка, регулировка, установка,
монтаж (конструкций, оборудования и т.д.) 3)
оборудование, оснащение, снаряжение
сборщик, слесарь-сборщик
выверка, выравнивание, регулировка
разделка кромок
сдирание, обдирание; зачистка; снятие верхнего
слоя
заплата
лёгкий водолаз, аквалангист
врачебный/медицинский осмотр
горючая смесь газов
делать чертеж, проектировать
юр. прекращение, недействительность права (на
что-л.)
While-reading activity
Think of the answers to the following questions:
1. How can you communicate to your company?
2. What can be a source of helpful information for a welder?
3. Who can be called a certified welder?
4. How do people apply for employment?
5. What professions are physical demanding?
6. What kind of career goals may a welder have?
7. What is formal training?
20
Give the Russian equivalents for the word combinations in italics in the text.
21
Reading
Text 5. Taking the Plunge:
A Guide to Starting an Underwater Welding Career
Over the years, a number of people
have expressed an interest in
careers in underwater welding, but
were unsure how to get started.
Welders, students, divers, and other
interested men and women have
contacted the American Welding
Society (AWS) for guidance. In order to help those prospective underwater
welder-divers, the D3B Subcommittee on Underwater Welding has provided
answers for some commonly asked questions.
1. What skills are prerequisite to entering the field of underwater
welding?
The skills suggested for entering the field of underwater welding can
best be defined by the following typical description of a welder-diver from
the AWS D3.6 Standard. "Welder-diver: A certified welder who is also a
commercial diver, capable of performing tasks associated with commercial
subsea work, weld setup and preparation, and who has the ability to weld in
accordance with the AWS D3.6." By description, an experienced welderdiver must possess: commercial diving skills (i.e., be familiar with the use of
specialized commercial diving equipment, have an understanding of diving
physiology, diving safety, rigging, the underwater environment,
communication, etc.); weld setup and preparation skills (i.e., the ability to
perform tasks typically assigned to a fitter or rigger, such as materials
alignment and materials preparation including beveling, stripping of
concrete, fitting a steel patch or repair plate, etc.,); and the ability to certify
to a required underwater weld procedure.
2. I am a certified surface welder, what other training do I need to
qualify as a welder-diver?
The majority of work performed by an average welder-diver does not
involve the welding operation itself, but rather executing the tasks that lead
up to and follow the actual welding activities. Except under special
circumstances, a welder-diver in most cases must posses both certified
welder skills and commercial diving skills. It is suggested that if you have no
prior commercial diving experience you should attend one of the recognized
commercial diving schools. The candidate may be required to pass a diving
physical prior to school acceptance and in some cases a written exam. It is
22
suggested that a dive physical be taken regardless, to avoid going through the
expense of training only to later find you have a disability that prevents your
entering the profession. Once that basic commercial diver training is
completed, it is common practice to apply for employment at one of many
commercial diving companies that offer underwater welding as a service. An
interview with the company of your choice is recommended to express your
career goals in underwater welding and past welding experience. Expect to
begin your career as a diver tender (apprentice diver) initially. As a diver
tender you will gain valuable practical experience while learning the trade.
3. I am already a certified diver, what other training do I need to
qualify as a welder-diver?
The welding processes, classes of weld and qualification tests
associated with underwater welding are described in ANSI/AWS D3.6. We
recommend the specification as a reference for weld procedure and welder
qualification. It is also a good source of other helpful information. If you are
already certified as a "commercial diver" and work for a company that offers
underwater welding services, it is recommended that you communicate to
your company your career objectives and ask what welder skills they are
looking for. If you are certified as a "scuba diver", it is suggested that you
attend a commercial diving school. Sport dive training does not include the
safe use of commercial diving equipment, offshore commercial work
environment/safety, and other education. Underwater welding is a skill you
also have to master once you obtain the basic commercial diving skills
required.
4. What are the age limitations of a welder-diver?
There is no age restriction on commercial welder-divers. There are,
however, physical requirements. It is recommended and generally required
that all commercial divers pass an annual dive physical. The commercial
diving profession is physical demanding. It is rare to see an active
commercial welder-diver over the age of 50.
5. What salary can I expect to make as a welder-diver?
We know some welder-divers earn $15,000 per year while others earn
in excess of $100,000. Because the majority of welder-divers are paid on a
project-by-project basis, salaries are subject to the same variables as work
availability. In addition, other factors such as depth, dive method and diving
environment affect pay rates. The company with whom you gain employment
should be able to tell you the salary range you can expect to earn.
6. What other skills are recommended to supplement my
qualifications as a welder-diver?
Ideally, a diving contractor would like its welder-divers to be "a jack of
all trades and a master of them all!" Practically speaking, possessing the
23
skills that are common to underwater welding operations, in addition to
welding and diving, are recommended. Primarily these skills are: underwater
cutting (oxyfuel, abrasive water jet, mechanical cutting equipment, etc.);
fitting and rigging; inspection and nondestructive testing (visual, magnetic
particle, ultrasonics, radiography, eddy current, etc.); drafting; and
underwater photography (still photo and video). The more skills the welderdiver maintains the more valuable he becomes in meeting project
qualification requirements. The most desirable underwater welder-divers are
those who are qualified to: assist the diving contractor in pre-job planning
(e.g., having the ability to photograph/video, draft and report on work
requirements prior to the actual underwater welding operation); cut, clean,
rig, install, and fit up the sections they will weld; and work with personnel
responsible for inspecting the completed welds. Formal training is
recommended for whatever skills you wish to qualify for. Maintaining the
qualifications you obtain is just as important as receiving them as there has
been many a job lost to a welder-diver who has let his certification lapse.
7. What future career opportunities are there for an experienced
welder-diver?
There are a number of career opportunities for experienced welderdivers. Many go on to become engineers, instructors, and diving operations
supervisors, fill management positions, qualify as AWS Certified Welding
Inspectors (CWI), and serve as consultants for underwater welding operations
and other related fields. Ideally, a career as a welder-diver should serve as a
stepping stone to other opportunities for those who choose the profession.
Industry has and will continue to demand higher quality standards for
underwater welds and more certification of underwater welding systems and
personnel.
After-reading activity
Continue filling in the following table:
Operations both surface
welder-divers do
weld setup and preparation, …
and Operations only welder-divers do
underwater cutting, …
24
Speaking
Correct the following statements to make them correspond to the text:
1. Welder-divers must have the skills of commercial diving but need not be
certified.
2. The majority of work performed by an average welder-diver includes only
welding operation itself.
3. Welder-divers apply for employment at commercial diving companies
before their diver training is completed.
4. Commercial welder-diver is the same as scuba diver.
5. You cannot be a welder-diver if you are over 50 years old.
6. To possess commercial diving skills means to be able to do underwater
weld procedures.
7. Welder-divers earn from $15,000 to $100,000 per year depending on their
work experience.
8. To pass a physical examination for welder diver you need to go through
formal training.
9. Past welding experience doesn’t count if you choose to be a welder-diver.
Answer the following questions:
1. Who can be a welder-diver?
2. What sorts of basic and supplementary skills must a welder-diver possess?
3. How can certified surface welders become welder-divers?
4. What is more important: receiving the welder-diver qualifications or
maintaining them?
5. Why do commercial divers pass an annual dive physical?
6. Do welder-divers have any future career opportunities?
7. Do you think surface welding equipment can be used underwater?
Translate the following sentences into Russian:
1. Большое количество людей проявляет интерес к профессии
подводного сварщика.
2. Сварщик-подводник – это квалифицированный сварщик,
обладающий всеми навыками, необходимыми для сварки на
поверхности и под водой.
3. Перед зачислением в школу сварщиков-подводников кандидаты
проходят обязательное медицинское освидетельствование.
25
4. Полезными навыками сварщиков-подводников являются: фото- и
видеосъемка, создание чертежа, установка оснастки и др.
5. Для многих профессиональных сварщиков навыки подводной сварки
становятся залогом дальнейшего карьерного роста.
Think and say
1. The word combination taking the plunge is a set phrase (связанное
фразеологическое сочетание). Is it a good title for this text? Why?
2. Another set phrase in the text is a stepping stone. What are possible
stepping stones in your welding career?
PART 2. THE HISTORY OF WELDING
Lead-in
Think of the answers for the following questions:
1. Why did welding become necessary?
2. Is welding a new profession?
3 Who were the first welders?
4. Who invented modern welding?
Vocabulary
forge
oxyacetylene
welding rod
MIG
TIG
выковывать, ковать
1) автогенный 2) кислородно-ацетиленовый
сварочный пруток
metal inert gas welding сварка металлическим
электродом в инертном газе
tungsten inert gas welding дуговая сварка
вольфрамовым электродом в среде инертного газа
горелка
arc (дуговая) сварка под флюсом
torch
submerged
welding
molten pool/puddle
сварочная ванна; ванна жидкого металла
26
Reading
Text 1. Welding History - A Story of Harnessing Heat
Joining metal and welding history go back several
millennia starting in the Bronze Age then Iron Age
in Europe then the Middle East. Welding was used
in the Iron pillar in Delhi, India, about 310 AD,
weighing 5.4 metric tons (picture at left). The
Middle Ages brought forge welding, blacksmiths
pounded hot metal until it bonded. In 1540,
Vannoccio Biringuccio released De la pirotechnia,
which includes descriptions of the forging operation.
Renaissance craftsmen gained skilled in the process,
and the welding continued to grow during the
following centuries.
Welding was transformed during the 19th century. In 1800, Sir
Humphrey Davy invented the electric arc, and advances in welding continued
with the metal electrode by a Russian, Nikolai Slavyanov, and an American,
C.L. Coffin late in the 1800s.
Acetylene was discovered in 1836 by Edmund Davy, but was not
practical in welding until about 1900, when a suitable blowtorch was
developed. At first, oxyfuel welding was the more popular welding method
due to its portability and relatively low cost. As the 20th century progressed,
it fell out of favor for industrial applications. It was largely replaced with arc
welding, as metal coverings (known as flux) for the electrode that stabilize
the arc and shield the base material from impurities continued to be
developed.
In 1881 a Russian inventor, Benardos demonstrated
the carbon electrode welding process. An arc was formed
between a moderately consumable carbon electrode and the
work. A rod was added to provide needed extra metal.
Thermite welding was invented in 1893, another
process, oxyfuel welding, became well established.
Around 1900, A. P. Strohmenger brought a coated
metal electrode in Britain, which had a more stable arc, and
in 1919, alternating current welding was invented by C.J. Holslag, but did not
become popular for another decade.
Resistance welding was developed during the end of the 19th century,
with the first patents going to Elihu Thompson in 1885, and he produced
advances over the next 15 years.
27
In 1904 Oscar Kjellberg in Sweden, who started ESAB, invented and
patented the covered electrode. This electric welding process made strong
welds of excellent quality.
World War I caused a major surge in the use of welding processes,
with the various military powers attempting to determine which of the several
new welding processes would be best. The British primarily used arc
welding, even constructing a ship, the Fulagar, with an entirely welded hull.
The Americans were more hesitant, but began to recognize the benefits of arc
welding when the process allowed them to repair their ships quickly after a
German attack in the New York Harbor at the beginning of the war. Arc
welding was first applied to aircraft during the war as well, as some German
airplane fuselages were constructed using the process.
During the 1920s, major advances were made in welding technology,
including the introduction of automatic welding in 1920, in which electrode
wire was fed continuously.
Shielding gas became a subject receiving much attention, as scientists
attempted to protect welds from the effects of oxygen and nitrogen in the
atmosphere. Porosity and brittleness were the primary problems, and the
solutions that developed included the use of hydrogen, argon, and helium as
welding atmospheres.
During the following decade, further advances allowed for the welding
of reactive metals like aluminum and magnesium. This, in conjunction with
developments in automatic welding, alternating current, and fluxes fed a
major expansion of arc welding during the 1930s and then during World War
II.
A significant invention was defined in a
patent by Alexander, filed in December 1924, and
became known as the Atomic Hydrogen Welding
Process. It looks like MIG welding but hydrogen
is used as the shielding gas which also provides
extra heat.A major innovation was described in a patent that defines the
Submerged Arc Process by Jones, Kennedy and Rothermund. This patent was
filed in October 1935 and assigned to Union Carbide Corporation. The
following was excepted from an article written by Bob Irving in he Welding
Journal: “The importance of welding was emphasized early in the war when
President Roosevelt sent a letter to Prime Minister Winston Churchill, who is
said to have read it aloud to the members of Britain's House of Commons.
The letter read in part, "Here there had been developed a welding technique
(referring to Submerged Arc Welding) which enables us to construct
28
standard merchant ships with a speed unequalled in the history of merchant
shipping."
Russell Meredith working at Northrop Aircraft Company in 1939-1941
invented the TIG process. This new process was called "Heliarc" as it used an
electric arc to melt the base material and helium to shield the molten puddle.
Mr.Jack Northrop's dream was to build a magnesium airframe for a lighter,
faster warplanes and his welding group invented the process and developed
the first TIG torches. The patents were sold to Linde who developed a
number of torches for different applications. They also developed procedures
for using Argon which was more available and less expensive than Helium.
In 1957, the flux-cored arc welding process debuted, in which the selfshielded wire electrode could be used with automatic equipment, resulting in
greatly increased welding speeds, and that same year, plasma arc welding
was invented. Electroslag welding was released in 1958, and it was followed
by its cousin, electrogas welding, in 1961.
Other recent developments in welding include the 1958 breakthrough
of electron beam welding, making
deep and narrow welding possible
through the concentrated heat
source. Following the invention of
the laser in 1960, laser beam welding
debuted several decades later, and
has proved to be especially useful in
high-speed, automated welding.
Both of these processes, however, continue to be quite expensive due the
high cost of the necessary equipment, and this has limited their applications.
After-reading activity
Find equivalents for the following words combinations in the text:
Угольный электрод, электрод с покрытием, защитный газ, торговое
судоходство, открытая печь, военный самолет, открытый горн,
источник тепла, признавать преимущества электродуговой сварки,
высокая стоимость.
Match the dates, names and inventions from the following table:
1540
1800
1800s.
Vannoccio Biringuccio
Sir Humphrey Davy
Nikolai Slavyanov, C.L. Coffin
29
discovered acetylene
invented the electric arc
developed metal
1836
1881
1900
1904
1919
1935
1924
electrode
Edmund Davy
brought a coated metal
electrode
A. P. Strohmenger
invented and patented
the covered electrode
Benardos
described forging
operation
C.J. Holslag
invented alternating
current
Oscar Kjellberg
demonstrated the
welding process with
carbon electrode
Jones, Kennedy and Rothermund developed Submerged
Arc Welding
Alexander
patented Atomic
Hydrogen Welding
process
After-reading discussion
True or false?
1. Arc welding was used to build the Iron pillar in Delhi, India.
2. The discovery of acetylene made it possible to achieve higher heating
temperatures.
3. The first electrode used in welding was a covered one.
4. The British Prime Minister Winston Churchill was a famous welder.
5. Oxygen is used as shielding gas in TIG welding.
6. The TIG process made it possible to construct planes faster.
Answer the following question on the text:
1. Which process was developed earlier, MIG or TIG?
2. Why is rod added in carbon electrode welding?
3. What is the difference between the Atomic Hydrogen Welding process and
the MIG process?
4. What kind of gas was first used to shield the molten puddle?
5. Is tungsten electrode consumable?
30
Speaking
Translate the following sentences from Russian into English:
1. Ковка – первый в истории метод соединения металлов, при котором
было необходимо нагреть соединяемые металлы до высокой
температуры на открытом пламени.
2. Открытие ацетилена и соединение его с кислородом позволило
значительно повысить температуру нагрева свариваемых металлов.
3. Российский изобретатель Бенардос впервые использовал
неплавящийся угольный электрод.
4. Использование электрода с покрытием значительно повысило
качество получаемых сварных соединений.
5. Изобретение дуговой сварки под флюсом позволило ускорить
строительство торговых судов.
6. При дуговой сварке вольфрамовым электродом в качестве инертного
газа использовался гелий, который позднее был заменен более дешевым
в получении аргоном.
Vocabulary
joining, joint
armour
carburization
brittle
interlayering
high-carbon
hammer forging
cast iron
blacksmith
jeweler
fusion
riveting
boiler
oxyacetylene
consumable
bare
coating
spot
соединение, связь, сращивание,
шов
броня
науглероживание
хрупкий, ломкий
чередование слоев
высокоуглеродистый
свободная ковка на молоте
чугун
кузнец
ювелир
плавка; расплавление
производить клёпку — rivet, join by
rivets
паровой котёл, бойлер
ацетилено-кислородный
расходуемый
непокрытый
покрытие
точечная
31
seam
sheet
butt
tungsten
beam
bonding
роликовая
лист
стыковая
вольфрам
луч
соединение, (с)крепление,
связывание
Skim the text to find out more facts about the history of welding.
Find the English equivalents in the text for the following word combinations:
Сварочная технология, твердое железо, кухонная утварь, листовая
сталь, сложное покрытие, алюминиевая проволока, сложное покрытие,
острая необходимость, проволока без покрытия.
Reading
Text 2. From the History of Welding
Welding is a technique used for joining metallic parts usually through
the application of heat. This technique was discovered during efforts to
manipulate iron into useful shapes. Welded blades were developed in the first
millennium AD, the most famous being those produced by Arab armourers
at Damascus, Syria. The process of carburization of iron to produce hard
steel was known at this time, but the resultant steel was very brittle. The
welding technique - which involved interlayering relatively soft and tough
iron with high-carbon material, followed by hammer forging - produced a
strong, tough blade.
In modern times the improvement in iron-making techniques,
especially the introduction of cast iron, restricted welding to the blacksmith
and the jeweler. Other joining techniques, such as fastening by bolts or
rivets, were widely applied to new products, from bridges and railway
engines to kitchen utensils.
Modern fusion welding processes are an outgrowth of the need to
obtain a continuous joint on large steel plates. Rivetting had been shown to
have disadvantages, especially for an enclosed container such as a boiler.
Gas welding, arc welding, and resistance welding all appeared at the end of
the 19th century. The first real attempt to adopt welding processes on a wide
scale was made during World War I. By 1916 the oxyacetylene process was
well developed, and the welding techniques employed then are still used. The
main improvements since then have been in equipment and safety. Arc
32
welding, using a consumable electrode, was also introduced in this period,
but the bare wires initially used produced brittle welds. A solution was found
by wrapping the bare wire with asbestos and an entwined aluminum wire.
The modern electrode, introduced in 1907, consists of a bare wire with a
complex coating of minerals and metals. Arc welding was not universally
used until World War II, when the urgent need for rapid means of
construction for shipping, power plants, transportation, and structures spurred
the necessary development work.
Resistance welding, invented in 1877 by Elihu Thomson, was accepted
long before arc welding for spot and seam joining of sheet. Butt welding for
chain making and joining bars and rods was developed during the 1920s. In
the 1940s the tungsten-inert gas process, using a nonconsumable tungsten
electrode to perform fusion welds, was introduced. In 1948 a new gasshielded process utilized a wire electrode that was consumed in the weld.
More recently, electron-beam welding, laser welding, and several solidphase processes such as diffusion bonding, friction welding, and ultrasonic
joining have been developed.
After-reading activity
Refer the following statements to each of the passages of the text:
1. Application of welding techniques is decreasing nowadays.
2. Welding originated from the attempts to shape metal into useful forms.
3. Resistance welding is one of the earliest types of joining metals.
4. Industrial development in the 1950-s expedited (ускорять) the advance of
welding technologies.
Speaking
True or false?
1. Only heat is used for joining metallic parts in welding.
2. The process of carburization of iron is rather new.
3. The blacksmith and the jeweler continue to use welding techniques in their
work.
4. Welding is the only technique of joining metallic parts.
5. The modern electrode consists of a bare wire with asbestos.
6. Arc welding was not used after World War II.
7. Diffusion bonding and friction welding are solid-phase processes.
33
8. Rivetting is now widely used for producing an enclosed container such as a
boiler.
Answer the following questions:
1. What is welding?
2. How was welding discovered?
3. Who were the first welders?
4. What did the first welding technique for making blades involve?
5. Did the improvement in iron-making techniques conduce to the
development of welding?
6. Is it efficient to apply riveting for making boilers?
7. When did gas, arc and resistance welding appear?
8. What was the quality of the welds produced by the arc welding using bare
wires like?
9. What does the coating of the modern electrode consist of?
10. What are the years 1877, 1916, and 1948 remarkable for in terms of
welding?
Translate from Russian into English:
1. Арабских оружейников, изготавливавших кованые клинки, можно
считать первыми сварщиками.
2. Появление методов сварки плавлением было обусловлено
необходимостью производства изделий из крупнолистовой стали.
3. Впервые сварка стала использоваться в массовом производстве во
время первой мировой войны.
4. Вторая мировая война ускорила внедрение электродуговой сварки.
5. Современный сварочный электрод имеет сложное покрытие,
состоящее из композитных материалов.
6. Помимо сварки, клепка и болтовые соединения являются основными
методами соединения металлов.
Writing
Write a short report on the history of welding mentioning:
Dates: first millennium AD, 1540, 1800, 1836, 1881, , 1877, 1881, 1892,
1900, 1904, 1907, 1924, 1935, 1948.
34
Names: Alexander, Jones, Kennedy and Rothermund, Morehead and Wilson,
Oscar Kjellberg, Benardos, Russell Meredith, Edmund Davy, Nikolai
Slavyanov, C.L. Coffin, Vannoccio Biringuccio, Sir Humphrey Davy.
Places: Syria, Russia, Sweden, the US, Britain;
Inventions: modern electrode, resistance welding, oxyacetylene process,
MIG, TIG, atomic hydrogen welding process, submerged arc welding, carbon
electrode.
Lead-in
Think of the answers for the following questions:
1. How can welding influence the history of a country?
2. In what fields of industry, in your opinion, is welding especially
important?
3. What modern machines and structures cannot be produced without
welding processes?
4. What welding process, arc or gas ones, has played a more important part in
developing new technologies? What particular aspect(s) of this
process/processes is/are of significance for industry development?
Vocabulary
war effort
rivetting
brittle fracture
notch
crack propagation
fusion welding
field welding
toughness
planeload
X-ray inspection
induction heating
structural steel
rolled steel
fillet weld
contact face
electroslag welding
военная экономика
клепка
хрупкий излом
зубец; вырез, паз, пропил, прорез
развитие трещин
сварка плавлением
сварка в полевых условиях, сварка при монтаже
твердость
полная загрузка самолета
рентгенодефектоскопия
индукционный нагрев
конструкционная сталь
стальной прокат
угловой сварной шов
поверхность контакта
электрошлаковая сварка
35
Pre-reading activity
Find the following figures in the text and say what they relate to:
140, 20, 5171, 2200, 1945, 525, 531, 2710, 250,000, 58, 117, 1915, 1931,
1977, 120, 176,000, 500,000, 586,000, 17,000, 80, 373,500, 52.
Model: 2200 - 2200 passengers were killed on the Mississippi River when
the steamboat Sultana blew up.
Reading
Text 3. Welding's Vital Part
in Major American Historical Events
Shipbuilding
The finest hours for U.S.
shipbuilding were during World
War II when 2710 Liberty ships,
531 Victory ships and 525 T-2
tankers were built for the war
effort. Through 1945, some 5171
vessels of all types were constructed
to American Bureau of Shipping (ABS) class during the Maritime
Commission wartime shipbuilding program. At this time in shipbuilding
history, welding was replacing riveting as the main method of assembly.
The importance of welding was emphasized early in the war when
President Roosevelt sent a letter to Prime Minister Winston Churchill, who is
said to have read it aloud to the members of Britain's House of Commons.
The letter read in part, "Here there had been developed a welding technique
which enables us to construct standard merchant ships with a speed
unequaled in the history of merchant shipping."
The technique the President was referring to was undoubtedly
submerged arc welding, which was capable of joining steel plate as much as
20 times faster than any other welding process at that time.
During this period of assimilation, eight Liberty ships were lost due to
a problem called brittle fracture. At first, many blamed welding, but history
would soon prove that the real cause of brittle fracture was steels that were
notch sensitive at operating temperatures. The steel was found to have high
sulfur and phosphorus contents. On more than 1400 ships, crack arrestors
were used to prevent crack propagation. No crack was known to grow past
36
an arrestor. This safeguard helped reduce casualties from 140 to 20 per
month.
The ASME Code
In the late 1920s and early 1930s, the welding of pressure vessels came
on the scene. Welding made possible a quantum jump in pressure attainable
because the process eliminated the low structural efficiency of the riveted
joint. Welding was widely utilized by industry as it strove to increase
operating efficiencies by the use of higher pressures and temperatures, all of
which meant thick-walled vessels. But before this occurred, a code for
fabrication was born from the aftermath of catastrophe.
On April 27, 1865, the steamboat Sultana blew up while transporting
2200 passengers on the Mississippi River. The cause of the catastrophe was
the sudden explosion of three of the steamboat's four boilers, and up to 1500
people were killed as a result. Most of the passengers were Union soldiers
homeward bound after surviving Confederate prison camps. In another
disaster on March 10, 1905, a fire tube boiler in a shoe factory in Brockton,
Mass., exploded, killing 58, injuring 117 and causing damages valued at
$250,000. These two incidents, and the many others between them, proved
there was a need to bring safety to boiler operation. So, a voluntary code of
construction went into effect in 1915 - the ASME Boiler Code.
As welding began to be used, a need for nondestructively examining
those welds emerged. In the 1920s, inspectors tested welds by tapping them
with hammers, then listening to the sound through stethoscopes. A dead
sound indicated a defective weld. By 1931, the revised Boiler Code accepted
welded vessels judged safe by radiographic testing. By this time, magnetic
particle testing was used to detect surface cracks that had been missed
radiographic testing. By this time, magnetic particle testing was used to
detect surface cracks that had been missed by radiographic inspection. In his
history of the ASME Code, A. M. Greene, Jr., referred to the late 1920s and
early 1930s as "the great years." It was during this period that fusion welding
received widespread acceptance. Nowadays, thousands of individuals who
make their living in welding live and breathe the ASME Code every minute
of the working day.
In 1977, Leonard Zick, chairman of the main committee of the ASME
Code, said, "It's more than a code; the related groups make up a safety
system. Our main objective is to provide requirements for new construction
of pressure-related items that, when followed, will provide safety to those
who use them and those who might be affected by their use. "
37
LNG Tankers
A triumph of the code was the huge
aluminum spheres built by General Dynamics
in Charleston, S.C. They were built to criteria
established by the U.S. Coast Guard and were
based on Section VIII, Division 1, of the
ASME Code.
At about 2 a.m. on October 2, 1976, the
first welded aluminum sphere for a liquefied
natural gas tanker was rolled out of a building
in Charleston, then moved over to a special
stand for final hydropneumatic testing. It soon passed the test with flying
colors. The sphere itself weighed 850 tons and measured 120 ft (36 m) in
diameter. Each sphere consisted of more than 100 precisely machined plates,
"orange peel" in shape. The plates were gas metal arc welded together using
7036 lb (3166 kg) of filler metal. Total length of the welds on each sphere
was 48.6 miles. Completed spheres were barged along the coast and
delivered onto steel tankers under construction at General Dynamics'
shipyard in Quincy, Mass. This type of LNG tanker was based on the MossRosenberg design from Norway.
At General Dynamics' facility in Charleston, 80% of the metalworking
manhours were spent welding. Much of the filler metal deposited in
Charleston was 5183 aluminum. The vertical joints were welded using
special equipment from Switzerland in which the operator rode in a customdesigned chair alongside the welding arc. At this distance, he was able to
monitor the weld and observe the oscillation of the 1Z.5 -mm diameter filler
metal. Actual welding was controlled
remotely. About 30 weld passes were
required for each joint.
The massive equatorial ring was
welded outdoors. In this setup, nine
heavily machined, curved aluminum
extrusions had to be welded together. To
do it, 88 GMA weld passes were made
from the outside and 60 more from the
inside.
The Alaska Pipeline
Perhaps no single welding event in history ever received so much
attention as did the Alaska Pipeline. Crews of seasoned welders braved
Alaska's frigid terrain to weld this large-diameter pipeline, from start to
finish. At one point, 17,000 people were working on the pipeline - 6% of the
38
total population of Alaska. The entire pipeline only disturbed about 12 square
miles of the 586,000 square miles of the state of Alaska.
Welders were called upon to handle and weld a new steel pipe thicker
and larger than most of them had ever encountered before, using electrodes
also new to most. And, the requirements were the stiffest they had ever seen.
The U.S. Department of the Interior and a new pipeline coordinating
group representing the state of Alaska instituted some changes. So, the
original specifications for field welding were tossed, replaced by much
stiffer requirements for weld toughness. Instead of the conventional pipeline
welding electrode planned originally for the bulk of field welding, the new
requirements required higher quality. The only electrode the engineers could
find that met the new requirements was an E8010-G filler metal from
Germany, so it was soon flown over by the planeload. Some of the Pipeline
Welders Union out of Tulsa, Okla., then welding in Alaska, had used this
electrode while working on lines in the North Sea, but most welders were
seeing it for the first time.
One of the requirements was 100% X-ray inspection of all welds. The
films were processed automatically in vans that traveled alongside the
welding crews.
Welders worked inside protective aluminum enclosures intended to
protect the weld joint from the wind. Lighting inside the enclosures enabled
welders to see what they were doing during Alaska's dark winter.
On the main pipeline, preheat and the heat between weld passes was
applied at first by spider-ring burners. Induction heating was used later
during construction.
High-Rise Construction
About 30 years ago, steel construction went into orbit. The 100-story
John Hancock Center in Chicago and the 110-story twin towers of New
York's World Trade Center were under construction. Above ground, the
World Trade Center required some 176,000 tons of fabricated structural
steel. The Sears Tower came later. Bethlehem Steel Corp. had received
orders for 200,000 tons of rolled steel products for the South Mall complex
in Albany, N.Y. Allied Structural Steel Co. was reported to have used
multiple-electrode gas metal arc welding in the fabrication of the First
National Bank of Chicago Building.
In a progress report on the erection of the critical corner pieces for the
first 22 floors of the 1107-ft (332-m) high John Hancock Center, an Allied
Structural Steel spokesman said various welding processes were being used
in that portion of the high-rise building. More than 12,000 tons of structural
steel were used in that section. Webs and flanges for each interior H column
39
were made up of A36 steel plate with thicknesses up to 6172 in. (16.5 cm).
The long fillet welds at the web-to-flange contact faces were made using the
submerged arc process, while the box consumed in shop fabrication for this
building, while 165,000 lb (74,250 kg) of weld metal was consumed during
field erection. Weld metal consumption in shop fabrication for the U.S. Steel
Building in Pittsburgh, Pa., reached 609,000 lb (274,050 kg).
During this same period, Kaiser Steel Corp. had used the consumable
guide version of electroslag welding to deposit 24,000 welds in the Bank of
America world headquarters building in San Francisco. At the time, this
building was regarded as the tallest earthquake-proof structure ever erected
on the West Coast. In terms of welding, one of the most intensive structures
built during this period was NASA's Vertical Assembly Building on Merritt
Island, Fla. Shop-welded sections for this giant structure consumed 830,000
lb (373,500 kg) of weld metal.
For the World Trade Center, Leslie E. Robertson, a partner in charge of
the New York office of Skilling, Helle, Christiansen, Robertson, said a
computer was used to produce the drawing lists, beam schedules, column
details and all schedules for exterior wall panels. Millions of IBM cards were
then sent to every fabricator. These cards gave fabricators the width, length,
thickness and grade of steel of every plate and section in all of the columns
and panels. "In addition," he said, "the fabricators are given all of the
requirements of every weld needed to make up the columns and panels.
Many of these cards are used as equable to the production of drawings. They
are sent directly from the designer to the fabricators. Draftsmen never
become involved."
Elsewhere in New York City, Leo Plofker, a partner in one of the city's
leading design engineering firms, extensively used welding in design. Among
Plofker's achievements are the Pan-Am Building and the all-welded, 52-story
office building known as 140 Broadway. "Our decision to make extensive
use of welding is strictly based on economics," he said. "Welded design
results in savings in steel. Field welding can cause some problems, but they
are not too serious as long as you maintain control over the welders and you
insist that qualified personnel be employed to perform nondestructive
testing of the welds."
After-reading activity
Find the following sentences in the text and express in your own words what
they mean:
1. Nowadays, thousands of individuals who make their living in welding live
and breathe the ASME Code every minute of the working day.
40
2. A. M. Greene, Jr. referred to the late 1920s and early 1930s as "the great
years."
3. About 30 years ago, steel construction went into orbit.
4. Welded design results in savings in steel.
5. In the late 1920s and early 1930s, the welding of pressure vessels came on
the scene.
6. In 1977, Leonard Zick, chairman of the main committee of the ASME
Code, said, “It's more than a code… ;”
Fill in the blanks:
1. Before welding, … was the main assembly method in constructing
standard merchant ships.
2. … was the fastest welding process for joining steel plate in 1940s.
3. The first quality inspectors used … to tap the metal and hear the noise.
4. The use of higher pressures and temperatures made it necessary to
construct … vessels.
5. Magnetic particle testing was more efficient than radiographic testing in
detecting … .
6. The use of IBM cards during the construction of the World Trade Center
made it possible not to involve … .
7. In case of X-ray inspection one has to process … .
Speaking
True or false?
1. In 1940s all the welding techniques known were fast enough to produce
ships.
2. Americans lost a lot of ships because of problems associated with welding.
3. Introduction of welding into the high pressure and temperature structures
construction made it possible to make a great advance in industry.
4. The ASME Code was introduced to ensure safety in boiler production.
5. Draftsmen played an important part in the construction of the World Trade
Center.
PART 3. WELDING PROCESSES & EQUIPMENT
Lead-in
You already know what kind of training you should go through to become
welder. Among other things, a welder should know about processes which
41
are similar to welding. Look through the vocabulary and the text below and
say what the main difference between welding and related metal joining
processes is.
Vocabulary
soldering
tinning
leading
brazing
sweat
gimmick
filler metal
filler rod
heat buildup
heat distortion
stitch welding
пайка; пайка мягким (легкоплавким) припоем
лужение; облуживание
свинцевание
1) пайка твердым припоем (из меди и цинка) 2)
покрытие медью
паять, запаивать, припаивать (in, on)
1) сложное приспособление Syn: gadget 2) а) прием,
трюк, уловка, ухищрение, хитрость
присадочный металл, присадка
присадочный пруток; присадочная проволока
теплообразование, тепловведение
деформация (материала) из-за теплового нагрева
прерывистая шовная сварка; точечная сварка
перекрывающимися точками; автоматическая
точечная сварка
Reading
Text 1. Introduction to Welding Processes & Equipment
Among the first things a new welder needs to understand, is what the
different kinds of welding processes and equipment are, and their application.
A quick rundown:
Terms:
Soldering: Bonding by melting a soft metal to the surface of pieces to be
joined. Low temperature. Good for joining dissimilar materials. Most
common solders are lead-tin alloys.
Tinning: A soldering process, where the surface of a metal is coated with
solder.
Leading: A form of soldering, solder is used to fill in the surface of metal.
Brazing: Similar to soldering, but uses a higher temperature to fuse the filler
metal to the work pieces. Stronger bond. (Includes "Silver Soldering") Work
heated to pre-melt temperatures.
42
Welding: Joining 2 similar work pieces by melting them together, usually
with an additional filler rod of some sort to take up space. Materials must be
similar.
Cutting: Work is heated to melting point and beyond, and "cut" by oxidizing
metal. (Literally burning it away).
Shield: A barrier to keep oxygen away from heated work to prevent
oxidation. Includes chemical coatings called flux (liquids, pastes, solids,
which may be vaporized into a barrier gas when heated), and inert gasses.
Oxidation of the surfaces will prevent proper bonding of the metals.
Gas Welding
Uses Flame from burning gas to create welding heat.
Propane torch: (Soldering, heating) Good for sweating pipes, starting fires,
and spending hours trying to heat frozen bolts, while the surrounding metal
gets just as hot.
Oxyacetylene torch: (Cutting, welding, brazing, soldering, leading) Most
universal and useful welding tool. (Uses Acetylene gas and Oxygen for hot
flame) With the right bits, rod, and technique, you can weld almost anything.
Good for cutting anything from sheet metal to the turret off a tank, lead
filling, brazing (a sort of hard soldering process) welding plate, welding sheet
metal, welding aluminium, heating frozen bolts, or alternately cutting them
off, drilling holes in plate, welding cast iron, shrinking and forming steel, and
can double as a flame thrower in a pinch. Drawbacks are: Overheating of
some types of work, harder to control quality of some processes.
Oxy-propane: (Soldering, brazing, heating) A cheap compromise between
low cost and portable propane, and Oxy-Acetylene. Better than the former,
not as good as the latter.
Arc welding
Uses an electric arc to create welding heat.
Basic AC & DC arc welders (AC is cheaper) Uses flux coated steel (or
other) rods of various types for different jobs. Makes some of the best welds
on heavy gauge steels and cast iron. Cutting rods can make clean holes
through thick stock, and are about the only thing which can cut Kryptonite
bike locks. Very difficult to weld thin metals. You can also get a carbon arc
torch to use on an arc welder to braze. Eastwood's "stitch" welder is a
gimmick used on an arc welder to buzz the rod in and out, which may help on
thinner stock. (learning how to weld better, or going to a different process is
usually a better idea.)
43
MIG (Metal Inert Gas): A DC arc welding process which uses filler metal
fed in the form of a spool of thin wire, shielded by flow of inert gas (He,
Argon) instead of flux used in Arc. Very fast, much easier than Arc Welding,
with less heat buildup. Very good for sheet metal, due to minimal heat
distortion. Harder to weld thick stock, as welds are weaker due to poorer
penetration. The modern choice for steel body work, it can also be used for
Aluminium with Argon as the shield gas.
TIG (Tungsten Inert Gas): A high frequency AC arc process which uses a
tungsten electrode shielded by an inert gas to create a fine, controllable torch.
Uses a separate filler rod, as in Oxy-Acetylene welding. Capable of welding
very thin metals. About the best process for Aluminium, Stainless steel, and
other exotic stuff.
Resistance welding: includes spot welding: Uses the heat generated by
electricity flowing through work to melt and fuse. i.e.- put an electrode on
either side of 2 overlapped sheets of steel, turn on power. Metal in between
heats up, and melts together. An old favorite for assembling car bodies.
Plasma Cutters: Not a welder, but related. A high voltage arc is used to
superheat and ionize a stream of air to the "plasma" state. The stream of
plasma makes a rapid, clean, narrow cut with minimal heating of the work
piece.
After-reading activity
Answer the following questions:
1. What is the main difference between soldering and brazing?
2. What is used by welders to prevent oxidation?
3. What makes soldering advantageous before welding?
4. What welding processes are suitable for welding thin/thick metal plates?
5. What makes plasma cutting better than gas cutting?
Vocabulary
coalescence
filler material
molten pool
gas flame
solid-phase
ultrasonic
friction
соединение, слипание; сращение
присадочный материал
ванна расплавленного металла, сварочная ванна
газовое пламя
твёрдая фаза
ультразвуковой
трение
44
furnace
diffusion
печь
1) рассеивание
2) диффузия
high-current
сильноточный
low-voltage
низковольтный, низкого напряжения
discharge
разряд
arc column
столб дуги
direct current (dc)
постоянный ток
alternating current переменный ток
(ac)
layer
слой; пласт; ряд
molten-metal
капля жидкого металла
droplet
flux
флюс
inert atmosphere
инертная среда
annulus
тех. узкое кольцо (зазор и т. п.)
torch
сварочная горелка (для автоматической сварки –
головка)
base metal
основной металл
grain
зерно
precipitation
осаждение
residual stress
остаточное напряжение
Find the English equivalents for the following words and word combinations:
источник тепла, расплавленный металл, необходимый размер, сварной
шов, не нагретый металл, механические свойства, максимум
температуры,
защищать
поверхности,
быстрое
охлаждение,
осуществлять контроль, препятствовать окислению, вступать в
химическую реакцию, термообработка, бомбардировка электронами,
зона термического [теплового] воздействия, общая потребляемая
энергия
Reading
Text 2. Basic Principles of Welding
A weld can be defined as a coalescence of metals produced by heating
to a suitable temperature with or without the application of pressure, and with
or without the use of a filler material.
45
In fusion welding a heat source generates sufficient heat to create and
maintain a molten pool of metal of the required size. The heat may be
supplied by electricity or by a gas flame. Electric resistance welding can be
considered fusion welding because some molten metal is formed.
Solid-phase processes produce welds without melting the base
material and without the addition of a filler metal. Pressure is always
employed, and generally some heat is provided. Frictional heat is developed
in ultrasonic and friction joining, and furnace heating is usually employed
in diffusion bonding.
The electric arc used in welding is a high-current, low-voltage
discharge generally in the range 10–2,000 amperes at 10–50 volts. An arc
column is complex but, broadly speaking, consists of a cathode that emits
electrons, a gas plasma for current conduction, and an anode region that
becomes comparatively hotter than the cathode due to electron bombardment.
Therefore, the electrode, if consumable, is made positive and, if
nonconsumable, is made negative. A direct current (dc) arc is usually used,
but alternating current (ac) arcs can be employed.
Total energy input in all welding processes exceeds that which is
required to produce a joint, because not all the heat generated can be
effectively utilized. Efficiencies vary from 60 to 90 percent, depending on the
process; some special processes deviate widely from this figure. Heat is lost
by conduction through the base metal and by radiation to the surroundings.
Most metals, when heated, react with the atmosphere or other nearby
metals. These reactions can be extremely detrimental to the properties of a
welded joint. Most metals, for example, rapidly oxidize when molten. A
layer of oxide can prevent proper bonding of the metal. Molten-metal
droplets coated with oxide become entrapped in the weld and make the joint
brittle. Some valuable materials added for specific properties react so quickly
on exposure to the air that the metal deposited does not have the same
composition as it had initially. These problems have led to the use of fluxes
and inert atmospheres.
In fusion welding the flux has a protective role in facilitating a
controlled reaction of the metal and then preventing oxidation by forming a
blanket over the molten material. Fluxes can be active and help in the process
or inactive and simply protect the surfaces during joining.
Inert atmospheres play a protective role similar to that of fluxes. In
gas-shielded metal-arc and gas-shielded tungsten-arc welding an inert gas —
usually argon—flows from an annulus surrounding the torch in a continuous
stream, displacing the air from around the arc. The gas does not chemically
react with the metal but simply protects it from contact with the oxygen in the
air.
46
The metallurgy of metal joining is important to the functional
capabilities of the joint. The arc weld illustrates all the basic features of a
joint. Three zones result from the passage of a welding arc: (1) the weld
metal, or fusion zone, (2) the heat-affected zone, and (3) the unaffected zone.
The weld metal is that portion of the joint that has been melted during
welding. The heat-affected zone is a region adjacent to the weld metal that
has not been welded but has undergone a change in microstructure or
mechanical properties due to the heat of welding. The unaffected material is
that which was not heated sufficiently to alter its properties.
Weld-metal composition and the conditions under which it freezes
(solidifies) significantly affect the ability of the joint to meet service
requirements. In arc welding, the weld metal comprises filler material plus
the base metal that has melted. After the arc passes, rapid cooling of the
weld metal occurs. A one-pass weld has a cast structure with columnar
grains extending from the edge of the molten pool to the centre of the weld.
In a multipass weld, this cast structure may be modified, depending on the
particular metal that is being welded.
The base metal adjacent to the weld, or the heat-affected zone, is
subjected to a range of temperature cycles, and its change in structure is
directly related to the peak temperature at any given point, the time of
exposure, and the cooling rates. The types of base metal are too numerous to
discuss here, but they can be grouped in three classes: (1) materials
unaffected by welding heat, (2) materials hardened by structural change, (3)
materials hardened by precipitation processes.
Welding produces stresses in materials. These forces are induced by
contraction of the weld metal and by expansion and then contraction of the
heat-affected zone. The unheated metal imposes a restraint on the above, and
as contraction predominates, the weld metal cannot contract freely, and a
stress is built up in the joint. This is generally known as residual stress, and
for some critical applications must be removed by heat treatment of the
whole fabrication. Residual stress is unavoidable in all welded structures, and
if it is not controlled bowing or distortion of the weldment will take place.
Control is exercised by welding technique, jigs and fixtures, fabrication
procedures, and final heat treatment.
After-reading activity
Complete the following sentences:
1. A characteristic feature of fusion welding is:
a) molten metal
b) low-voltage discharge
47
c) inert atmosphere
2. Furnace heating is usually employed in
a) friction joining b) diffusion bonding
c) ultrasonic joining
3. The consumable electrode is made
a) negative b) positive c) neither
4. Total energy input in all welding processes is
a) is greater than required to produce a joint
b) is smaller than required
to produce a joint c) equals to required to produce a joint
5. Reactions of most metals with the atmosphere or other nearby metals can
1) improve the properties of a welded joint b) make the properties of a
welded joint worse
c) never influence the properties of a welded joint
6. The most common gas used in gas-shielded metal-arc and gas-shielded
tungsten-arc welding is
a) argon
b) oxygen c) carbon dioxide
7. If not controlled, residual stress results in
a) precipitation processes in welded structures, b) freezing of the weldmetal c) bowing or distortion of the weldment.
True or false?
1. There is always a welding pool in solid-phase welding processes.
2. Total energy input in all welding processes is greater than needed to
produce a weld.
3. Reactions of metals with the atmosphere or other nearby metals are
favorable to the properties of a welded joint.
4. Fluxes and inert atmospheres play a protective role and prevent oxidation.
5. The heat-affected zone is a region with unaltered properties.
6. Residual stress is present in all welded structures.
Answer the following questions:
1. What is a weld?
2. How can the heat be supplied for welding?
3. Is pressure employed in solid-phase processes?
4. What does an arc column consist of?
5. How is heat applied during welding?
6. What is the role of inert atmospheres?
7. What can make a joint brittle while welding?
8. What does the weld metal comprise in arc welding?
9. What is the base metal influenced by?
10. How can residual stress in welded structures be controlled?
48
Reading
Text 3. Characteristics of the Principal Welding Processes
Welding is the process of joining together pieces of metal or metallic
parts by bringing them into intimate proximity and heating the places of
contact to a state of fusion or plasticity. This leads to interpenetration of the
atoms of the metals in the weld zone, and a strong inseparable joint is
formed after the metals have cooled.
Welding finds widespread application in almost all branches of
industry and construction. Welding is extensively employed in the
fabrication and erection of steel structures in industrial construction and civil
engineering (frames of industrial buildings, bridges, etc.), vessels of weldedplate construction (steel reservoirs, pipelines, etc.) and concrete
reinforcement.
Welding processes may be classified according to the source of energy
employed for heating the metals and the state of the metal at the place being
welded. A master chart of the principal welding processes is shown on
the next page.
In fusion welding the welding area is heated by a concentrated source
of heat to a molten state and filler metal must be added to the weld. In
accordance with the method applied for feeding the filler metal to the weld,
welding procedures are classified as manual, semi-automatic or automatic
welding.
Pressure welding processes involve the heating of the metallic parts
only to a plastic or lightly fused state and forcing them together with
external pressure. Pressure welding processes are applied to metals which
are capable of being brought to a plastic state by heating or due to the
action of external forces. It has been established that in this process the most
weldable metals prove to be those metals which have higher thermal
conductivity. Such metals more rapidly dissipate heat from the weld zone
and do not allow an excessively high temperature to be concentrated in a
small area (the latter may lead to considerable internal stress).
The quality of the joint obtained in pressure welding depends to a great
extent upon the magnitude of the applied pressure and the temperature to
which the metal is heated at the moment of welding. The higher this
temperature, the less unit pressure will be required to produce the weld.
Proper cleaning of the surface to be joined is one of the main conditions for
obtaining high-quality welds in pressure-welding procedures.
49
Master Chart of the Principal Welding Processes
After-reading activity
Find equivalents in the text for the following word combinations:
Welding is widely used, welded area, disperse heat, parts made of steel,
designing and producing metal structures, pressing together.
50
Translate the following sentences from Russian into English using the
information from the text:
1. Взаимопроникновение атомов металлических изделий под
действием высокой температуры и давления приводит к образованию
сварного соединения.
2. Сварка находит широкое применение во всех отраслях
промышленности и в строительстве.
3. При сварке давлением лучше свариваются металлы с большей
теплопроводностью,
а
необходимым
условием
получения
высококачественного соединения является предварительная очистка
свариваемых поверхностей.
4. При сварке плавлением используется присадочный металл,
подача которого может осуществляться автоматически.
5. Чем ниже температура нагрева металла, тем выше необходимое
для получения соединения давление.
6. Изготовление и монтаж стальных конструкций невозможны без
применения сварки.
7. Сварка широко применяется в строительстве для создания
каркаса зданий.
8. По типу подачи присадочного материала сварочные процессы
делятся на ручные и механизированные.
9. Концентрация высоких температур на малых участках
(неравномерность нагрева) приводит к появлению внутреннего
напряжения в металлах.
10. Свариваемые детали должны находиться в непосредственной
близости друг от друга.
Use the information of the Master Chart of welding processes above to
complete the following sentences:
1. The two basic welding processes are ... .
2. The fusion processes consist of … .
3. Among these, arc welding can be accomplished …
4. Arc welding with consumable electrodes includes the following
types… .
5. Carbon arc welding, atomic hydrogen welding, inert gas tungsten
arc welding refer to … .
6. The pressure processes include … .
7. Resistance welding is divided into three types … .
51
Translate the following text from Russian into English:
Cвaрка – это процесс получения неразъёмного соединения
деталей машин, конструкций и сооружений посредством местного
разогрева (вплоть до плавления), пластической деформации или при
совместном действии того и другого; суть сварки заключается в таком
взаимном проникновении или сближении поверхностей свариваемых
тел, при котором в месте соединения начинают действовать силы
межатомного (межмолекулярного) сцепления. Различают сварку
плавлением (дуговая, газовая, плазменная, электроннолучевая,
лазерная) и сварку давлением (контактная, конденсаторная, холодная,
ультразвуковая, термокомпрессионная, диффузионная). Выбор того
или иного способа сварки зависит от физико-химических свойств
свариваемых материалов, условий проведения сварки, от толщины
соединяемых деталей и конструкции соединений.
Lead-in.
Remember all the welding types which you have read about before and make
a complete list of these types.
Think and say: What can be the difference between the principle
(“traditional”) and alternative types of welding? Why are traditional welding
processes not sufficient?
Vocabulary
cold welding
friction welding
холодная сварка (в вакууме)
сварка трением
laser welding
лазерная сварка
diffusion bonding
диффузное соединение
ultrasonic welding
ультразвуковая сварка
explosive welding
сварка взрывом
butt
anvil
honeycomb
fin
стык
наковальня
пористый
ребро, пластина
52
finished
integrated circuitry
fuse
pneumatic tooling
punch presses
готовый; обработанный
интегральная схемотехника
плавить, расплавлять
пневматический инструмент
пресс-штамп
Reading
Text 4. Alternative Types of Welding
Cold welding
Cold welding, the joining of materials without the use of heat, can be
accomplished simply by pressing them together. Surfaces have to be well
prepared, and pressure sufficient to produce 35 to 90 percent deformation at
the joint is necessary, depending on the material. Lapped joints in sheets and
cold-butt welding of wires constitute the major applications of this
technique. Pressure can be applied by punch presses, rolling stands, or
pneumatic tooling. Pressures of 1,400,000 to 2,800,000 kilopascals (200,000
to 400,000 pounds per square inch) are needed to produce a joint in
aluminum; almost all other metals need higher pressures.
Friction welding
In friction welding two work pieces are brought together under load
with one part rapidly revolving. Frictional heat is developed at the interface
until the material becomes plastic, at which time the rotation is stopped and
the load is increased to consolidate the joint. A strong joint results with the
plastic deformation, and in this sense the process may be considered a
variation of pressure welding. The process is self-regulating, for, as the
temperature at the joint rises, the friction coefficient is reduced and
overheating cannot occur. The machines are almost like lathes in appearance.
Speed, force, and time are the main variables. The process has been
automated for the production of axle casings in the automotive industry.
Laser welding
Laser welding is accomplished when the light energy emitted from a
laser source focused upon a workpiece to fuse materials together. The limited
availability of lasers of sufficient power for most welding purposes has so far
restricted its use in this area. Another difficulty is that the speed and the
thickness that can be welded are controlled not so much by power but by the
thermal conductivity of the metals and by the avoidance of metal
vaporization at the surface. Particular applications of the process with very
53
thin materials up to 0.5 mm (0.02 inch) have, however, been very successful.
The process is useful in the joining of miniaturized electrical circuitry.
Diffusion bonding
This type of bonding relies on the effect of applied pressure at an
elevated temperature for an appreciable period of time. Generally, the
pressure applied must be less than that necessary to cause 5 percent
deformation so that the process can be applied to finished machine parts. The
process has been used most extensively in the aerospace industries for joining
materials and shapes that otherwise could not be made—for example,
multiple-finned channels and honeycomb construction. Steel can be
diffusion bonded at above 1,000° C (1,800° F) in a few minutes.
Ultrasonic welding
Ultrasonic joining is achieved by clamping the two pieces to be welded
between an anvil and a vibrating probe or sonotrode. The vibration raises the
temperature at the interface and produces the weld. The main variables are
the clamping force, power input, and welding time. A weld can be made in
0.005 second on thin wires and up to 1 second with material 1.3 mm (0.05
inch) thick. Spot welds and continuous seam welds are made with good
reliability. Applications include extensive use on lead bonding to integrated
circuitry, transistor canning, and aluminum can bodies.
Explosive welding
Explosive welding takes place when two plates are impacted together
under an explosive force at high velocity. The lower plate is laid on a firm
surface, such as a heavier steel plate. The upper plate is placed carefully at an
angle of approximately 5° to the lower plate with a sheet of explosive
material on top. The charge is detonated from the hinge of the two plates, and
a weld takes place in microseconds by very rapid plastic deformation of the
material at the interface. A completed weld has the appearance of waves at
the joint caused by a jetting action of metal between the plates.
After-reading activity
Match a welding type with its description
1. Cold welding
2. Friction welding
A. Light energy is used to weld parts together.
B. The weld is formed at the expense of the applied
pressure at a high temperature for a long period of
time.
54
3. Laser welding
4. Diffusion bonding
5. Ultrasonic welding
6. Explosive welding
C. Vibration is used to generate heat necessary to
produce a weld. e
D. The heat to accomplish the joint is generated by
rotation.
E. The most important factor to accomplish the weld
is pressure. No heat is applied.
F. Rapid plastic deformation of the welded materials
is caused by detonation.
Fill in the blanks with the right words (namely, types of welding) from the list
below:
1. …welding is successfully used in manufacture of small elements of
electric circuits.
2. Heat is not used in … welding.
3. … is widely used in aerospace industries.
4. Vibration is used in …welding.
5. Plastic deformation is the basic principle in … welding.
6. … welding is impossible without pressure and high temperature.
7. In … welding one of the parts being welded revolves.
Translate the following sentences into Russian:
1.При холодной сварке поверхности должны быть тщательно
подготовлены.
2. Скорость и толщина свариваемых деталей зависит не столько от
мощности лазера, сколько от теплопроводности металла.
3. Этот вид сварки наиболее широко используется в авиакосмической
промышленности.
4. Холодная сварка – это сварка без использования тепловой энергии,
когда две свариваемые поверхности, обладающие высокой
пластичностью, с силой прижимают друг к другу.
5. Использование точечной и шовной сварки позволяет получать
сварные соединения высокой прочности.
6. Основными переменными величинами при этом виде сварки
являются подводимое тепло, время сварки и сила сжатия.
7. Фрикционным разогревом добиваются пластичности материала,
затем вращение цапфы останавливают и увеличивают давление для
обеспечения сваривания поверхностей.
8. Сварной шов имеет чешуйчатый вид, что является результатом
обдува струей сжатого воздуха.
55
Writing
Make a summary of alternative welding processes indicating their
application capabilities. Start like this:
1. Cold welding that is welding without heat makes it possible to join thin
sheets of aluminum.
2. Friction welding…
PART 4. ARC AND GAS WELDING IN DETAIL
Lead-in
Remember the definition and description of arc welding from the previous
chapters. What, in your opinion, makes arc welding one of the two main
welding processes so widely applied in modern industry?
Find the English equivalents for the following Russian phrases in the text:
Постоянный/переменный ток, электрическая дуга, присадочный
материал, источник питания, положительно заряженный анод, остатки
флюса, волна типа "синусоида", гармоническая волна/ прямоугольная
волна, плавящийся электрод, свариваемые металлы, пересечение
нулевого уровня, пленка ПВХ, светофильтры, наплавка, горючие
материалы
Reading
Text 1. Arc Welding
Arc welding refers to a group of welding processes that use a welding
power supply to create an electric arc between an electrode and the base
material to melt metals at the welding point. They can use either direct (DC)
or alternating (AC) current, and consumable or non-consumable electrodes.
The welding region is sometimes protected by some type of inert or semiinert gas, known as a shielding gas, and filler material is sometimes used as
well.
56
Power supplies
To supply the electrical energy
necessary for arc welding processes, a
number of different power supplies can be
used. The most common classification is
constant current power supplies and
constant voltage power supplies. In arc
welding, the voltage is directly related to
the length of the arc, and the current is
related to the amount of heat input.
Constant current power supplies are most
A constant current welding power
often used for manual welding processes
supply capable of AC and DC
such as gas tungsten arc welding and
shielded metal arc welding, because they maintain a relatively constant
current even as the voltage varies. This is important because in manual
welding, it can be difficult to hold the electrode perfectly steady, and as a
result, the arc length and thus voltage tend to fluctuate. Constant voltage
power supplies hold the voltage constant and vary the current, and as a result,
are most often used for automated welding processes such as gas metal arc
welding, flux cored arc welding, and submerged arc welding. In these
processes, arc length is kept constant, since any fluctuation in the distance
between the wire and the base material is quickly rectified by a large change
in current. For example, if the wire and the base material get too close, the
current will rapidly increase, which in turn causes the heat to increase and the
tip of the wire to melt, returning it to its original separation distance.
The type of current used in arc welding also plays an important role in
welding. Consumable electrode processes such as shielded metal arc welding
and gas metal arc welding generally use direct current, but the electrode can
be charged either positively or negatively. In welding, the positively charged
anode will have a greater heat concentration, and as a result, changing the
polarity of the electrode has an impact on weld properties. If the electrode is
positively charged, it will melt more quickly, increasing weld penetration and
welding speed. Alternatively, a negatively charged electrode results in more
shallow welds. Non-consumable electrode processes, such as gas tungsten arc
welding, can use either type of direct current, as well as alternating current.
However, with direct current, because the electrode only creates the arc and
does not provide filler material, a positively charged electrode causes shallow
welds, while a negatively charged electrode makes deeper welds. Alternating
current rapidly moves between these two, resulting in medium-penetration
welds. One disadvantage of AC, the fact that the arc must be re-ignited after
57
every zero crossing, has been addressed with the invention of special power
units that produce a square wave pattern instead of the normal sine wave,
making rapid zero crossings possible and minimizing the effects of the
problem.
Consumable electrode methods
One of the most common types of arc
welding is shielded metal arc welding
(SMAW), which is also known as
manual metal arc welding (MMA) or
stick welding. Electric current is used to
strike an arc between the base material
and consumable electrode rod, which is
made of steel and is covered with a flux
that protects the weld area from
Shielded metal arc welding a pipe
oxidation and contamination by
producing CO2 gas during the welding process. The electrode core itself acts
as filler material, making a separate filler unnecessary. The process is very
versatile, requiring little operator training and inexpensive equipment.
However, weld times are rather slow, since the consumable electrodes must
be frequently replaced and because slag, the residue from the flux, must be
chipped away after welding. Furthermore, the process is generally limited to
welding ferrous materials, though special electrodes have made possible the
welding of cast iron, nickel, aluminum, copper, and other metals. The
versatility of the method makes it popular in a number of applications,
including repair work and construction.
Gas metal arc welding (GMAW), also known as metal inert gas (MIG)
welding, is a semi-automatic or automatic welding process that uses a
continuous wire feed as an electrode and an inert or semi-inert gas mixture to
protect the weld from contamination. Since the electrode is continuous,
welding speeds are greater for GMAW than for SMAW. However, because
of the additional equipment, the process is less portable and versatile, but still
useful for industrial applications. The process can be applied to a wide
variety of metals, both ferrous and non-ferrous. A related process, flux-cored
arc welding (FCAW), uses similar equipment but uses wire consisting of a
steel electrode surrounding a powder fill material. This cored wire is more
expensive than the standard solid wire and can generate fumes and/or slag,
but it permits higher welding speed and greater metal penetration.
58
Submerged arc welding (SAW) is a high-productivity welding method
in which the arc is struck beneath a covering layer of flux. This increases arc
quality, since contaminants in the atmosphere are blocked by the flux. The
slag that forms on the weld generally comes off by itself, and combined with
the use of a continuous wire feed, the weld deposition rate is high. Working
conditions are much improved over other arc welding processes, since the
flux hides the arc and no smoke is produced. The process is commonly used
in industry, especially for large products.
Non-consumable electrode methods
Gas tungsten arc welding (GTAW), or
tungsten inert gas (TIG) welding, is a
manual welding process that uses a nonconsumable electrode made of tungsten,
an inert or semi-inert gas mixture, and a
separate filler material. Especially useful
for welding thin materials, this method
is characterized by a stable arc and high
quality welds, but it requires significant
Gas tungsten arc welding
operator skill and can only be
accomplished at relatively low speeds. It can be used on nearly all weldable
metals, though it is most often applied to stainless steel and light metals. It is
often used when quality welds are extremely important, such as in bicycle,
aircraft and naval applications. A related process, plasma arc welding, also
uses a tungsten electrode but uses plasma gas to make the arc. The arc is
more concentrated than the GTAW arc, making transverse control more
critical and thus generally restricting the technique to a mechanized process.
Because of its stable current, the method can be used on a wider range of
material thicknesses than can the GTAW process, and furthermore, it is much
faster. It can be applied to all of the same materials as GTAW except
magnesium, and automated welding of stainless steel is one important
application of the process. A variation of the process is plasma cutting, an
efficient steel cutting process. Other arc welding processes include atomic
hydrogen welding, carbon arc welding, electroslag welding, electrogas
welding, and stud arc welding.
59
Safety issues
Welding, without the proper precautions, can be a dangerous and
unhealthy practice. However, with the use of new technology and proper
protection, the risks of injury and death associated with welding can be
greatly reduced. Because many common welding procedures involve an open
electric arc or flame, the risk of burns is significant. To prevent them, welders
wear protective clothing in the form of heavy leather gloves and protective
long sleeve jackets to avoid exposure to extreme heat and flames.
Additionally, the brightness of the weld area leads to a condition called arc
eye in which ultraviolet light causes the inflammation of the cornea and can
burn the retinas of the eyes. Goggles and helmets with dark face plates are
worn to prevent this exposure, and in recent years, new helmet models have
been produced that feature a face plate that self-darkens upon exposure to
high amounts of UV light. To protect bystanders, transparent welding
curtains often surround the welding area. These curtains, made of a polyvinyl
chloride plastic film, shield nearby workers from exposure to the UV light
from the electric arc, but should not be used to replace the filter glass used in
helmets.
Welders are also often exposed to dangerous gases and particulate
matter. Processes like flux-cored arc welding and shielded metal arc welding
produce smoke containing particles of various types of oxides. The size of
the particles in question tends to influence the toxicity of the fumes, with
smaller particles presenting a greater danger. Additionally, many processes
produce various gases, most commonly carbon dioxide and ozone, and fumes
that can prove dangerous if ventilation is inadequate. Furthermore, because
the use of compressed gases and flames in many welding processes pose an
explosion and fire risk, some common precautions include limiting the
amount of oxygen in the air and keeping combustible materials away from
the workplace.
After reading activity
Match the terms and their meaning
1. Anode
2. Ultraviolet
(UV) light
A Fabrication process that joins materials, usually metals
or thermoplastics, by causing coalescence
B Difference of electrical potential between two points of
an electrical network, expressed in volts [1]. It is a measure
of the capacity of an electric field to cause an electric
60
3. Flux
4. Welding
5. Alternating
current (AC)
6. Carbon
dioxide
7. Oxidation
8. Goggles and
safety glasses
9. Ozone
10. Toxicity
current in an electrical conductor.
C Electrical current whose magnitude and direction vary
cyclically, as opposed to direct current, whose direction
remains constant.
D (from the Greek άνοδος = 'going up') is the electrode in a
device that electrons flow out of to return to the circuit.
Literally, the path through which the electrons ascend out
of an electrolyte solution. The other charged electrode in
the same cell or device is the cathode.
E In metallurgy, a substance which facilitates soldering,
brazing, and welding by chemically cleaning the metals to
be joined. Common ….s are: ammonium chloride or rosin
for soldering tin; hydrochloric acid and zinc chloride for
soldering galvanized iron (and other zinc surfaces); and
borax for brazing, and welding ferrous metals.
F Atmospheric gas comprised of one carbon and two
oxygen atoms. A very widely known chemical compound,
it is often referred to by its formula CO2. It is present in the
Earth's atmosphere at a low concentration and acts as a
greenhouse gas. In its solid state, it is called dry ice. It is a
major component of the carbon cycle.
G Loss of an electron by a molecule, atom or ion
H (Formerly wolfram) is a chemical element that has the
symbol W (L. wolframium) and atomic number 74. A very
hard, heavy, steel-gray to white transition metal, it is found
in several ores including wolframite and scheelite and is
remarkable for its robust physical properties, especially the
fact that it has a higher melting point than any other nonalloy in existence. The pure form is used mainly in
electrical applications but its many compounds and alloys
are widely used in many applications (most notably in light
bulb filaments, and as both the filament and target in most
X-ray tubes and in space-age superalloys).
I In metallurgy a ferrous alloy with a minimum of 10%
chromium content. The name originates from the fact that it
does not stain, corrode or rust as easily as ordinary steel.
This material is also called corrosion resistant steel when it
is not detailed exactly to its alloy type and grade,
particularly in the aviation industry.
J also known as arc flash, welder's flash, corneal flash
61
11. Stainless
steel
12. Arc eye
13. Tungsten
14. Voltage
burns, or flash burns, is a painful ocular condition
sometimes experienced by welders who have failed to use
adequate eye protection. It can also occur due to light from
sunbeds, light reflected from snow (known as snow
blindness), water or sand. The intense ultraviolet light
emitted by the arc causes a superficial and painful keratitis.
K Triatomic molecule, consisting of three oxygen atoms. It
is an allotrope of oxygen that is much less stable than the
diatomic species O2. It is a pale blue gas at standard
temperature and pressure. It forms a dark blue liquid below
−112 °C and a dark blue solid below −193 °C. A powerful
oxidizing agent. It is also unstable, decaying to ordinary
diatomic oxygen: 2 O3 → 3 O2.
L From Greek τοξικότητα – poisonousness). It can refer to
the effect on a whole organism, such as a human or a
bacterium or a plant, or to a substructure, such as the liver.
By extension, the word may be metaphorically used to
describe toxic effects on larger and more complex groups,
such as the family unit or "society at large". The skull and
crossbones is a common symbol for it.
M Forms of protective eyewear that usually enclose or
protect the eye area in order to prevent particulates or
chemicals from striking the eyes. They are used in
chemistry laboratories and in woodworking. They are often
used in snow sports as well, and in swimming. Goggles are
often worn when using power tools such as drills or
chainsaws to prevent flying particles from damaging the
eyes.
N Electromagnetic radiation with a wavelength shorter than
that of visible light, but longer than soft X-rays.
Speaking
True or false?
1. Filler material is always necessary for arc welding.
2. The amount of heat input at the welding point depends on the voltage.
3. Shielded metal arc welding is a consumable electrode process.
4. Consumable welding processes use any type of current.
5. Consumable electrode methods are faster than none-consumable ones.
6. TIG welding requires little operator training.
62
7. Submerged arc welding is used to weld large work pieces.
Answer the following questions and summarize the text:
1. What is arc welding?
2. What kind of current and electrodes are used in arc welding?
3. What is the welded region protected by?
4. Why is constant current power supply most often used for manual welding
processes?
5. How does the type of the electrode charge (positive/negative) influence the
speed of welding and weld penetration?
6. What problem is related to the use of alternating current in gas tungsten
welding?
7. What is the function of flux in shielded metal arc welding?
8. What are the main advantages and disadvantages of manual metal arc
welding?
9. Which type of metal arc welding uses a separate filler material?
10. What do the welding protection clothes include?
Translate the following sentences from Russian into English:
1. Зона сварки при электродуговых процессах защищается защитным
газом.
2. При сварке с использованием плавящихся электродов используется
как постоянный, так и переменный ток.
3.При РДС электрод является присадочным материалом.
4. Благодаря разнообразию способов электродуговой сварки она
находит широкое применение в различных отраслях производства.
5. Для защиты сварщиков от ультрафиолетового излучения
электрической дуги используются светофильтры.
6. При недостаточной вентиляции газы могут представлять опасность
для здоровья.
7. Благодаря отсутствию дыма при дуговой сварке под флюсом условия
труда гораздо лучше, чем при других способах электродуговой сварки.
8. В целях предосторожности не следует держать воспламеняющиеся
предметы вблизи проведения сварочных работ.
.
63
Reading
Below find information about some less frequently used arc welding
processes. After reading the text, think and say why these processes are less
common in industry. Consider their advantages and disadvantages.
Atomic Hydrogen Welding (AHW) is an arc welding process that uses an
arc between two metal tungsten electrodes in a shielding atmosphere of
hydrogen and without the application of pressure. Shielding is obtained from
the hydrogen. Filler metal may or may not be used. In this process, the arc is
maintained entirely independent of the work or parts being welded. The
work is a part of the electrical circuit only to the extent that a portion of the
arc comes in contact with the work, at which time a voltage exists between
the work and each electrode.
Carbon Arc Welding (CAW) is a process which produces coalescence of
metals by heating them with an arc between a nonconsumable carbon
(graphite) electrode and the work-piece. It was the first arc-welding process
ever developed but is not used for many applications today, having been
replaced by twin carbon arc welding and other variations.
Twin carbon arc welding (TCAW) in which the arc is established between
two carbon electrodes
Gas carbon arc welding (CAW-G) no longer has commercial significance
Electroslag welding is a highly productive welding process developed in the
United States during the 1930s. It involves the melting of the surfaces of the
metal workpieces and the filler metal with a molten slag to cause
coalescence. An electric arc is passed through the slag to heat it, but the arc
itself is extinguished by the slag. Electroslag welding is commonly used to
weld in a vertical orientation, and is particularly popular with steels. In the
1970s, it was used extensively in bridges, ships, and other large metal
structures. However, in 1977 the Federal Highway Administration banned its
use in welds for some structural members of bridges, due to concerns of weld
imperfections and poor properties. Benefits of the process include its high
metal deposition rates. Many welding processes require more than one pass
for welding thick workpieces, but often a single pass is sufficient for
electroslag welding. The process is also very efficient, since joint preparation
and materials handling are minimized while filler metal utilization is high.
The process is also safe and clean, with no arc flash and low weld splatter or
distortion.
Electrogas welding (EGW) is a continuous vertical position arc welding
process developed in 1961, in which an arc is struck between a consumable
electrode and the workpiece. A shielding gas is sometimes used, but pressure
64
is not applied. A major difference between EGW and its cousin electroslag
welding is that the arc in EGW is not extinguished, instead remaining struck
throughout the welding process. It is used to make square-groove welds for
butt and welding, especially in the shipbuilding industry and in the
construction of storage tanks. In EGW, the heat of the welding arc causes the
electrode and workpieces to melt and flow into the cavity between the parts
being welded. This molten metal solidifies from the bottom up, joining the
parts being welded together. The weld area is protected from atmospheric
contamination by a separate shielding gas, or by the gas produced by the
disintegration of a flux-cored electrode wire. The electrode is guided into the
weld area by either a consumable electrode guide tube, like the one used in
electroslag welding, or a moving head. When the consumable guide tube is
used, the weld pool is composed of molten metal coming from the parts being
welded, the electrode, and the guide tube. The moving head variation uses an
assembly of an electrode guide tube which travels upwards as the weld is
laid, keeping it from melting. Electrogas welding can be applied to most
steels, including low and medium carbon steels, low alloy high strength
steels, and some stainless steels. Quenched and tempered steels may also be
welded by the process, provided that the proper amount of heat is applied.
Welds must be vertical, varying to either side by a maximum of 15 degrees.
Like other arc welding processes, EGW requires that the operator wear a
welding helmet and proper attire to prevent exposure to molten metal and the
bright welding arc. Compared to other processes, a large amount of molten
metal is present during welding, and this poses an additional safety and fire
hazard. Since the process is often performed at great heights, the work and
equipment must be properly secured, and the operator should wear a safety
harness to prevent injury in the event of a fall. EGW uses a constant voltage,
direct current welding power supply, and the electrode has positive polarity.
A wire feeder is used to supply the electrode, which is selected based on the
material being welded. The electrode can be flux-cored to provide the weld
with protection from atmospheric contamination, or a shielding gas can be
used with a solid wire electrode. The welding head is attached to an apparatus
that elevates during the welding process. Also attached to the apparatus are
backing shoes which restrain the weld to the width of the workpieces. To
prevent them from melting, they are made of copper and are water-cooled.
They must be fit tightly against the joint to prevent leaks.
Stud welding is a form of spot welding where a bolt or specially formed nut
is welded on to another metal part. The bolts may be automatically fed into
the spot welder. Weld nuts generally have a flange with small nubs that melt
to form the weld. Studs have a necked down, unthreaded area for the same
purpose.
65
Speaking
True or false
1. Electrogas welding is less hazardous than electroslag welding.
2. Electroslag welding is more frequently used to weld in a horizontal
orientation.
3. Carbon Arc Welding is broadly used in industry in the present time.
4. Filler metal is always necessary in Atomic Hydrogen Welding.
5. Quenched and tempered steels are not welded using Electrogas welding.
6. Carbon Arc Welding is the newest arc welding process.
Answer the following questions:
1. What kind of electrodes are used in Electrogas and Atomic Hydrogen
Welding processes?
2. What structures can be welded by Electrogas welding?
3. Can thick workpieces be easily welded by Electroslag welding?
4. Why is Electrogas welding relatively unsafe and hazardous?
5. What is the difference between Electrogas and Electroslag welding?
6. Why does the operator have to wear protective clothes?
Complete the following sentences:
1. To ensure safety while using arc welding processed operators have to
wear… .
2. Electroslag welding is no more used to weld… .
3. In Electrogas welding the weld area is protected from atmospheric
contamination … .
4. In Atomic Hydrogen Welding the work itself becomes… .
5. Since Electrogas welding is performed at great heigh… .
Writing
Write a short report arc welding mentioning:
Types (SMAW, MMA, GMAW, MIG, FCAW, SAW, GTAW, TIG,
electroslag welding, stud arc welding, EGW, TCAW);
Types of filler material used (consumable/none-consumable, covered/bare
electrode/wire);
Type of current used (direct/alternating);
Type of shielding gas used (helium, argon, CO2);
66
Major application areas.
Lead-in
Try to answer the following questions:
What is the difference in methods of gas gutting and gas welding?
Is there any difference in equipment used for gas welding and gas cutting?
What might be the advantages and disadvantages of gas cutting compared to
other methods of cutting metals?
Do you remember what appeared before: arc or gas welding?
What type of cutting (arc or gas) is :
a) more expensive
b) more operator skills demanding
c) safer
e) faster
f) more precise?
Present your arguments.
Do you know what metals (steels) are better cut using gas welding?
Vocabulary
rig
hose
spark
igniter
wrench
outfit
pressure gauge
leak
orifice
single-stage
(regulator)
flashback
какое-л. приспособление, устройство, механизм
Syn: apparatus , device
шланг
искра
воспламенитель
гаечный ключ
агрегат; оборудование, принадлежности, набор
(приборов, инструментов)
манометр
течь, протечка; утечка
отверстие
однокамерный
обратный удар пламени (проникающий в шланг
сварочной горелки)
67
Reading
Text 2. Oxygas Cutting Equipment
An oxygas cutting outfit usually consists of a cylinder of acetylene or
MAPP gas, a cylinder of oxygen, two regulators, two lengths of hose with
fittings, and
a
cutting
torch with
tips (figure
at left). An
oxygas
cutting
outfit also
is referred
to as a
cutting rig.
Oxygas cutting outfit
In addition to the basic equipment mentioned above, numerous types of
auxiliary equipment are used in oxygas cutting. An important item is the
spark igniter that is used to light
the torch (figure at right, view A).
Another item you use is an
apparatus wrench. It is similar in
design to the one shown in figure
at right, view B.
A Spark igniter and B Apparatus wrench
68
The apparatus wrench is sometimes called
a gang wrench because it fits all the connections
on the cutting rig. Note that the wrench shown has
a raised opening in the handle that serves as an
A portable oxygas cutting and
welding outfit
acetylene tank key.
Other common accessories include tip
cleaners, cylinder trucks, clamps, and holding jigs. Personal safety apparel,
such as goggles, hand shields, gloves, leather aprons, sleeves, and leggings,
are essential and should be worn as required for the job at hand.
Oxygas cutting equipment can be stationary or portable. A portable
oxygas outfit, such as the one shown in figure above, is an advantage when it
is necessary to move the equipment from one job to another.
To conduct your cutting requirements, you must be able to set up the
cutting equipment and make the required adjustments needed to perform the
cutting operation. For this reason it is important you understand the purpose
and function of the basic pieces of equipment that make up the cutting outfit.
But, before discussing the equipment, let’s look at the gases most often used
in cutting: acetylene, MAPP gas, and oxygen.
Acetylene
Acetylene is a flammable fuel gas composed of carbon and hydrogen
having the chemical formula C2H2.When burned with oxygen, acetylene
produces a hot flame, having a temperature between 5700°F and 6300°F.
Acetylene is a colorless gas, having a disagreeable odor that is readily
detected even when the gas is highly diluted with air. When a portable
welding outfit, similar to the one shown in
figure above is used, acetylene is obtained
directly from the cylinder. In the case of
stationary equipment, similar to the acetylene
cylinder bank shown in figure at right, the
acetylene can be piped to a number of
individual cutting stations.
Hazards: Pure acetylene is self-explosive
if stored in the free state under a pressure of
29.4 pounds per square inch (psi). A slight
shock is likely to cause it to explode.
WARNING: Acetylene becomes extremely
dangerous if used above 15 pounds pressure.
69
Cylinder Design
Acetylene can be safely compressed up to 275 psi when dissolved in
acetone and stored in specially designed cylinders filled with porous material,
such as balsa wood, charcoal, finely shredded asbestos, corn pith, portland
cement, or infusorial earth. These porous filler materials aid in the prevention
of high-pressure gas pockets forming in the cylinder.
Acetone is a liquid chemical that dissolves large portions of acetylene
under pressure without changing the nature of the gas. Being a liquid, acetone
can be drawn from an acetylene cylinder when it is not upright. You should
not store acetylene cylinders on their side, but if they are, you must let the
cylinder stand upright for a minimum of 2 hours before using. This allows the
acetone to settle to the bottom of the cylinder.
NOTE:
Acetone
contaminates
the
hoses,
regulators,
torch, and disrupts the
flame.
Acetylene
is
measured in cubic
feet.
The
most
common
cylinder
sizes are 130-, 290-,
and
330-cubic-foot
capacity. A common
standard size cylinder
holds 225 cubic feet
of acetylene. Just
because a cylinder has
a
225-cubic-foot
capacity does not necessarily mean it has 225 cubic feet of acetylene in it.
Because it is dissolved in acetone, you cannot judge how much acetylene is
left in a cylinder by gauge pressure. The pressure of the acetylene cylinder
will remain fairly constant until most of the gas is consumed.
An example of an acetylene cylinder is shown in figure above. These
cylinders are equipped with fusible plugs that relieve excess pressure if the
cylinder is exposed to undo heat. A common standard acetylene cylinder
contains 225 cubic feet of acetylene and weighs about 250 pounds. The
acetylene cylinder is yellow, and all compressed-gas cylinders are colorcoded for identification. More on the color coding of cylinders is covered
later in this lesson.
70
Mapp Gas
MAPP (methylacetylene-propadiene) is an all-purpose industrial fuel
having the high-flame temperature of acetylene but has the handling
characteristics of propane. Being a liquid, MAPP is sold by the pound, rather
than by the cubic foot, as with acetylene. One cylinder containing 70 pounds
of MAPP gas can accomplish the work of more than six and one-half 225cubic-foot acetylene cylinders; therefore, 70 pounds of MAPP gas is equal to
1,500 cubic feet of acetylene.
Cylinder Design
Total weight for a MAPP cylinder, which has the same physical size as
a 225-cubic-foot acetylene cylinder, is 120 pounds (70 pounds which is
MAPP gas). MAPP cylinders contain only liquid fuel. There is no cylinder
packing or acetone to impair fuel withdrawal; therefore, the entire contents of
a MAPP cylinder can be used. For heavy-use situations, a MAPP cylinder
delivers more than twice as much gas as an acetylene cylinder for the same
time period.
MAPP Characteristics
Because of its superior heat transfer characteristics, MAPP produces a
flame temperature of 5300°F when burned with oxygen. MAPP equals, or
exceeds, the performance of acetylene for cutting, heating, and brazing.
MAPP is not sensitive to shock and is nonflammable in the absence of
oxygen. There is no chance of an explosion if a cylinder is bumped, jarred, or
dropped. You can store or transport the cylinders in any position with no
danger of forming an explosive gas pocket. The characteristic odor, while
harmless, gives warnings of fuel leaks in the equipment long before a
dangerous condition can occur. MAPP gas is not restricted to a maximum
working pressure of 15 psig, as is acetylene. In jobs requiring higher
pressures and gas flows, MAPP can be used safely at the full-cylinder
pressure of 95 psig at 70°F. Because of this, MAPP is an excellent gas for
underwater work.
Bulk MAPP Gas
Bulk MAPP gas facilities, similar to liquid oxygen stations, are
installed at some activities where large supplies of the gas are used. In bulk
installations, MAPP gas is delivered through a piping system directly to the
user points. Maximum pressure is controlled centrally for efficiency and
economy. Cylinder-filling facilities are also available from bulk installations
that allow users to fill their cylinders on site. Filling a 70-pound MAPP
cylinder takes one man about 1 minute and is essentially like pumping water
from a large tank to a smaller one.
MAPP Gas Safety
71
MAPP gas vapor is stable up to 600°F and 1,100 psig when exposed to
an 825°F probe. The explosive limits of MAPP gas are 3.4 percent to 10.8
percent in air or 2.5 percent to 80 percent in oxygen. As shown in figure 4-6,
you can see these limits are narrow in comparison with that of acetylene.
MAPP gas has a highly detectable odor. The smell is detectable at 100 ppm,
or at a concentration of 1/340th of its lower explosive limit. Small fuel-gas
systems may leak 1 or 1 1/2 pounds of fuel or more in an 8-hour shift; bulk
systems will leak even more. Fuel-gas leaks are often difficult to find and
often go unnoticed; however, a MAPP gas leak is easy to detect and can be
repaired before it becomes dangerous. MAPP toxicity is rated “very slight,”
but high concentrations (5,000 ppm) may have an anesthetic effect. Local eye
or skin contact with MAPP gas vapor causes no adverse effect; however, the
liquid fuel can cause dangerous frostlike burns due to the cooling caused by
the rapid evaporation of the liquid. The identification markings on a MAPP
cylinder are a yellow body with band “B” colored orange and the top yellow.
Oxygen
Oxygen is a colorless, tasteless, and odorless gas and is slightly heavier
than air. It is nonflammable but supports combustion with other elements. In
its free state, oxygen is one of the more common elements. The atmosphere is
made up of about 21 parts of oxygen and 78 parts of nitrogen, the remainder
being rare gases. Rusting of ferrous metals, discoloration of copper, and
corrosion of aluminum are all due to the action of atmospheric oxygen. This
action is known as oxidation. Oxygen is obtained commercially either by the
liquid-air process or by the electrolytic process. In the liquid-air process, the
air is compressed and then cooled to a point where the gases become liquid
(approximately –375°F). The temperature is then raised to above –321 ‘F, at
which point the nitrogen in the air becomes gas again and is removed. When
the temperature of the remaining liquid is raised to –297°F, the oxygen forms
gas and is drawn off. The oxygen is further purified and compressed into
cylinders for use. The other process by which oxygen is produced— the
electrolytic process—consists of running an electrical current through water
to which an acid or an alkali has been added. The oxygen collects at the
positive terminal and is drawn off through pipes to a container.
Oxygen is supplied for oxyacetylene welding in seamless steel
cylinders. The color of a standard oxygen cylinder used for industrial
purposes is solid green. Oxygen cylinders are made in several sizes. The size
most often used in welding and cutting is the 244-cubic-foot capacity
cylinder. This cylinder is 9 inches in diameter, 51 inches high, and weighs
about 145 pounds and is charged to a pressure of 2,200 psi at 70°F. You can
72
determine the amount of oxygen in a compressed gas cylinder by reading the
volume scale on the high-pressure gauge attached to the regulator.
Regulators
You must be able to reduce the high-pressure gas in a cylinder to a
working pressure before you can use it. This pressure reduction is done by a
regulator or reducing valve. The one basic job of all regulators is to take the
high-pressure gas from the cylinder and reduce it to a level that can be safely
used. Not only do they control the pressure but they also control the flow
(volume of gas per hour).
Regulators come in all sizes and types. Some are designed for highpressure oxygen cylinders (2,200 psig), while others are designed for lowpressure gases, such as natural gas (5 psig). Some gases like nitrous oxide or
carbon dioxide freeze when their pressure is reduced so they require
electrically heated regulators.
Most regulators have two gauges: one indicates the cylinder pressure
when the valve is opened and the other indicates the pressure of the gas
coming out of the regulator. You must open the regulator before you get a
reading on the second gauge. This is the delivery pressure of the gas, and you
must set the pressure that you need for your particular job.
The pressures that you read on regulator gauges is called gauge
pressure. If you are using pounds per square inch, it should be written as psig
(this acronym means pounds per square inch gauge). When the gauge on a
cylinder reads zero, this does not mean that the cylinder is empty. In
actuality, the cylinder is still full of gas, but the pressure is equal to the
surrounding atmospheric pressure. Remember: no gas cylinder is empty
unless it has been pumped out by a vacuum pump.
There are two types of regulators that control the flow of gas from a
cylinder. These are either single-stage or double-stage regulators.
Single-Stage Regulators
Regulators are used on both high- and
low-pressure systems. Figure at left shows two
SINGLE-STAGE regulators: one for acetylene
and one for oxygen. The regulator mechanism
consists of a nozzle through which the gases
pass, a valve seat to close off the nozzle, a
diaphragm, and balancing springs. These
mechanisms are all enclosed in a suitable
housing. Fuel-gas regulators and oxygen
regulators are basically the same design. The
73
Single stage regulators
difference being those designed for fuel gases are not made to withstand the
high pressures that oxygen regulators are subjected to.
In the oxygen regulator, the oxygen enters through the high-pressure
inlet connection and passes through a glass wool falter that removes dust and
dirt. Turning the adjusting screw IN (clockwise) allows the oxygen to pass
from the high-pressure chamber to the low-pressure chamber of the regulator,
through the regulator outlet, and through the hose to the torch. Turning the
adjusting screw further clockwise increases the working pressure; turning it
counterclockwise decreases the working pressure.
The high-pressure gauge on an oxygen regulator is graduated from 0 to
3,000 psig and from 0 to 220 in cubic feet. This allows readings of the gauge
to determine cylinder pressure and cubic content. Gauges are calibrated to
read correctly at 70°F. The working pressure gauge may be graduated in
“psig” from 0 to 150, 0 to 200, or from 0 to 400, depending upon the type of
regulator used. For example, on regulators designed for heavy cutting, the
working pressure gauge is graduated from 0 to 400.
The major disadvantage of single-stage regulators is that the working
gas pressure you set will decrease as the cylinder pressure decreases;
therefore, you must constantly monitor and reset the regulator if you require a
fixed pressure and flow rate. Keeping the gas pressure and flow rate constant
is too much to expect from a regulator that has to reduce the pressure of a full
cylinder from 2,200 psig to 5 psig. This is where double-stage regulators
solve the problem.
Double-Stage
Regulators
The
double-stage
regulator is similar in
principle to the onestage regulator.
The
main
difference being that
the total pressure drop
takes place in two
stages instead of one.
In the high-pressure
Double stage regulators
stage, the cylinder
pressure is reduced to
an intermediate pressure that was predetermined by the manufacturer. In the
low-pressure stage, the pressure is again reduced from the intermediate
74
pressure to the working pressure you have chosen. A typical double-stage
regulator is shown in figure above.
Problems And Safety
Regulators are precise and complicated pieces of equipment.
Carelessness can do more to ruin a regulator than any other gas-using
equipment. One can easily damage a regulator by simply forgetting to wipe
clean the cylinder, regulator, or hose connections. When you open a highpressure cylinder, the gas can rush into the regulator at the speed of sound. If
there is any dirt present in the connections, it will be blasted into the
precision-fitted valve seats, causing them to leak. This results in a condition
that is known as creep. Creep occurs when you shut of the regulator but not
the cylinder and gas pressure is still being delivered to the low-pressure side.
Regulators are built with a minimum of two relief devices that protect
you and the equipment in the case of regulator creep or high-pressure gas
being released into the regulator all at once. All regulator gauges have
blowout backs that release the pressure from the back of the gauge before the
gauge glass explodes. Nowadays, most manufacturers use shatterproof plastic
instead of glass. The regulator body is also protected by safety devices.
Blowout disks or spring-loaded relief valves are the two most common types
of devices used. When a blowout disk ruptures, it sounds like a cannon.
Spring-loaded relief valves usually make howling or shrieking like noises. In
either case, your first action, after you recover from your initial fright, should
be to turn off the cylinder valve. Remove the regulator and tag it for repair or
disposal. When opening a gas cylinder, you should just “crack” the valve a
little. This should be done before attaching the regulator and every time
thereafter. By opening the cylinder before connecting the regulator, you blow
out any dirt or other foreign material that might be in the cylinder nozzle.
Also, there is the possibility of a regulator exploding if the cylinder valve is
opened rapidly.
WARNING: Oil or other petroleum products must never be used
around oxygen regulators because these products will either cause a regulator
explosion or fire
Hoses
The hoses used to make the connections between the torch and the
regulators must be strong, nonporous, light, and flexible enough to make
torch movements easy. They must be made to withstand internal pressures
that can reach as high as 100 psig. The rubber used in hose manufacture is
specially treated to remove the sulfur that could cause spontaneous
combustion.
75
Welding hose is available in single- and double-hose lengths. Size is
determined by the inside diameter, and the proper size to use depends on the
type of work for which it is intended. Hose used for light work has a 3/16 or
1/4 inch inside diameter and one or two plies of fabric. For heavy-duty
welding and cutting operations, use a hose with an inside diameter of 5/16
inch and three to five plies of fabric. Single hose is available in the standard
sizes as well as 1/2-, 3/4-, and 1-inch sizes. These larger sizes are for heavyduty heating and for use on large
cutting machines.
The most common type of
cutting and welding hose is the
twin or double hose that consists
of the fuel hose and the oxygen
hose joined together side by
side. They are joined together by
either a special rib or by clamps.
Because they are joined
together, the hoses are less
likely to become tangled and are
Hoses
easier to move from place to
place.
The length of hose you use is important. The delivery pressure at the
torch varies with the length of the hose. A 20-foot, 3/16-inch hose maybe
adequate for a job, but if the same hose was 50 feet long, the pressure drop
would result in insufficient gas flow to the torch. Longer hoses require larger
inside diameters to ensure the correct flow of gas to the torch. When you are
having problems welding or cutting, this is one area to check. The hoses used
for fuel gas and oxygen are identical in construction, but they differ in color.
The oxygen hose cover is GREEN, and the fuel-gas hose cover is RED. This
color coding aids in the prevention of mishaps that could lead to dangerous
accidents.
All connections for welding and cutting hoses have been standardized
by the Compressed Gas Association. Letter grades A, B, C, D, and E plus the
type of gas used correspond directly with the connections on the regulators.
A, B, and C are the most common size connections. A-size is for low-flow
rates; B-size for medium-flow rates; and C-size is for heavy-flow rates. D
and E sizes are for large cutting and heating torches.
When ordering connections, you must specify the type of gas the hose
will be carrying. This is because the connections will be threaded differently
for different types of gas. Fuel gases use left-hand threads, while oxygen uses
right-hand threads. The reason for this is to prevent the accidental hookup of
76
a fuel gas to a life-support oxygen system or vice versa. The basic hose
connection consists of a nut and gland. The nut has threads on the inside that
match up with the male inlet and outlet on the torch and regulator. The gland
slides inside the hose and is held in place by a ferrule that has been crimped.
The nut is loose and can be turned by hand or a wrench to tighten the
threaded nut onto the equipment.
Another important item that is often overlooked is check valves. These
inexpensive valves prevent personal injuries and save valuable equipment
from flashbacks. When ordering, make sure you specify the type of gas,
connection size, and thread design. The check valves should be installed
between the torch connection and the hose.
Cutting Torches
The equipment and accessories for oxygas cutting are the same as for
oxygas welding except that you use a cutting torch or a cutting attachment
instead of a welding torch. The main difference between the cutting torch and
the welding torch is that the cutting torch has an additional tube for highpressure cutting oxygen. The flow of high-pressure oxygen is controlled from
a valve on the handle of the cutting torch. In the standard cutting torch, the
valve may be in the form of a trigger assembly like the one in figure below.
On most torches, the cutting oxygen mechanism is designed so the cutting
oxygen can be turned on gradually. The gradual opening of the cutting
oxygen valve is particularly helpful in operations, such as hole piercing and
rivet cutting.
Torch Body
Most welding
torches are designed
so the body of the
torch can accept either
welding tips or a
One piece oxygas cutting torch
cutting
attachment.
This type of torch is called a combination torch. The advantage of this type of
torch is the ease in changing from the welding mode to the cutting mode.
There is no need to disconnect the hoses; you just unscrew the welding tip
and then screw on the cutting attachment. The high-pressure cutting oxygen
is controlled by a lever on the torch handle, as shown in figure below.
Cutting Torch Tips
As in welding, you must use the proper size cutting tip if quality work is to
be done. The preheat flames must furnish just the right amount of heat, and
the oxygen jet orifice must deliver the correct amount of oxygen at just the
77
right pressure and velocity to produce a clean cut. All of this must be done
with a minimum consumption of oxygen and fuel gases. Careless workers
and workers not acquainted with the correct procedures waste both oxygen
and fuel gas.
Combination torch
Each manufacturer makes many different types of cutting tips. Although the
orifice arrangements and the tips are much the same among the
manufacturers, the part of the tip that fits into the torch head often differs in
design.
Because of these differences, there is the possibility of having two or
three different types of cutting torches in your kits. Make sure that the cutting
tips match the cutting attachment and ensure that the cutting attachment
matches the torch body. Figure above shows the different styles of tips, their
orifice arrangements and their uses. The tips and sears are designed to
produce an even flow of gas and to keep themselves as cool as possible. The
seats must produce leakproof joints. If the joints leak, the preheat gases could
mix with the cutting oxygen or escape to the atmosphere, resulting in poor
cuts or the possibility of flashbacks.
To make clean and economical cuts, you must keep the tip orifices and
passages clean and free of burrs and slag. If the tips become dirty or
misshapened, they should be put aside for restoration.
Tip Maintenance
In cutting operations, the stream of cutting oxygen sometimes blows
slag and molten metal into the tip orifices which partially clogs them. When
this happens, you should clean the orifices thoroughly before you use the tip
again. A small amount of slag or metal in an orifice will seriously interfere
with the cutting operation. You should follow the recommendations of the
torch manufacturer as to the size of drill or tip cleaner to use for cleaning the
orifices. If you do not have a tip cleaner or drill, you may use a piece of soft
copper wire. Do not use twist drills, nails, or welding rods for cleaning tips
because these items are likely to enlarge and distort the orifices.
78
Clean the orifices of the cutting torch tip in the same manner as the
single orifice of the welding torch tip. Remember: the proper technique for
cleaning the tips is to push the cleaner straight in and out of the orifice. Be
careful not to turn or twist the cleaning wire. Figure above shows a typical set
of tip cleaners.
Occasionally the cleaning of the tips causes enlargement and distortion
of the orifices, even when using the proper tip cleaners. If the orifices
become enlarged, you will get shorter and thicker preheating flames; in
addition, the jet of cutting oxygen will spread, rather than leave the torch, in
the form of a long, thin stream. If the orifices become belled for a short
distance at the end, you can sometimes correct this by rubbing the tip back
and forth against emery cloth placed on a flat surface. This action wears
down the end of the tip where the orifices have been belled, thus bringing the
orifices back to their original size.
Obviously, this procedure will not work if the damage is great or if the
belling extends more than a slight distance into the orifice. After
reconditioning a tip, you may test it by lighting the torch and observing the
preheating flames. If the flames are too short, the orifices are still partially
blocked. If the flames snap out when you close the valves, the orifices are
still distorted.
If the tip seat is dirty or scaled and does not properly fit into the torch
head, heat the tip to a dull red and quench it in water. This will loosen the
scale and dirt enough so you can rub it off with a soft cloth.
Speaking
True or false?
1. Oxygas cutting outfit and cutting rig are different things.
2. A gang wrench is used to light the torch.
3. Acetone has a favourable effect on the cutting equipment.
4. The acetylene cylinder is painted blue.
5. MAPP is a very toxic gas.
6. Acetone is a solid body that dissolves large portions of acetylene under
pressure.
7. Cylinder valve should be opened slowly to prevent explosion.
8. Local eye or skin contact with MAPP liquid fuel gas can cause dangerous
frostlike burns.
9. Twist drills, nails, or welding rods must not be used for cleaning tips.
79
Continue the following sentences:
1. An oxygas cutting outfit usually includes… .
2. The auxiliary cutting equipment may consist of … .
3. Acetylene is a flammable fuel gas that has the following characteristics: …
4. Acetone is a liquid chemical that …
5. MAPP is characterized by …
6. The action of atmospheric oxygen, oxidation, manifests itself in …
7. Personal safety clothes for welders involved in cutting operation include
… 8. The hoses that connect the torch and the regulators must be … .
Translate the following sentences into English:
1. Для правильного использования сварочной аппаратуры сварщик
должен знать назначение и функции ее основных узлов.
2. Для обеспечения безопасности перед началом работы необходимо
довести давление газа до рабочего и отрегулировать пламя.
3. Перед присоединением регулятора к цилиндру необходимо удалить с
сопла цилиндра пыль и другие инородные материалы.
4. Редукторы давления выпускаются различных типов и размеров, как
для цилиндров высокого, так и низкого давления.
5. Для предотвращения случайной подачи топливного газа к
кислородной системе и наоборот используются соединения с разным
направлением резьбы.
6. При засорении сопла резака пламя предварительного нагрева
расширяется.
7. Соприкосновение редуктора давления с нефтепродуктами может
вызвать взрыв или возгорание последнего.
8. По своим рабочим характеристикам метилацетилен-аллен
превосходит ацетилен при резке, подогреве либо пайке.
9. Редукторы давления требуют тщательного ухода.
10. Шланги для подачи горючего газа и кислорода маркируются
разными цветами и чаще всего скрепляются вместе для предотвращения
спутывания.
11. Баллон с газом не может считаться пустым, пока газ не будет
откачан насосом.
Compare operating characteristics of acetylene and MAPP gas according to
some of the parameters and fill in the table below:
Acetylene
MAPP
The gas is sold by
(pounds or cubic meters)
80
Cylinder packing (level
of
maximum
compression)
Stability (temperature)
Cylinders contain (pure
fuel or not)
Dangerous effects on
health
Reading
Skim the text and do the tasks:
Text 3. Oxy-Fuel Welding and Cutting
Oxy-fuel welding is a welding process commonly called oxyacetylene
welding since acetylene is the predominant choice for a fuel, or often simply
gas welding. A virtually identical procedure, with a different type of gas
torch, is used for cutting metal and called oxy-fuel cutting. In gas welding
and cutting, the heat energy and high temperature needed to melt the metal is
obtained by the combustion of a fuel gas with oxygen in a torch. This sort of
torch is often called a blowtorch.
Fuels
Compressed gas cylinders
containing oxygen oxygen and
MAPP gas
The most commonly used fuel gas is
acetylene. Other gases used are liquefied
petroleum gas (LPG), natural gas, hydrogen, and
MAPP gas.
Acetylene can be made near where the
welding is being done in an acetylene generator.
More often it is made elsewhere and shipped to
the welding site in special containers. These
containers are packed with various porous
materials (e.g. kapok fibre), then filled about
half way with acetone. The acetylene dissolves
into the acetone. This method is necessary
because above 207 kPa (30 lbf/in²) acetylene is
unstable and may explode. There is about 1700
81
kPa (250 lbf/in²) of pressure in the tank when full. Acetylene when burned
with oxygen gives a temperature of 3200°C to 3500°C (5800°F to 6300°F),
which is the highest temperature of any of the commonly used gaseous fuels.
Hydrogen has a clean flame and is good for use on aluminum. It can be
used at a higher pressure than acetylene and is therefore useful for
underwater welding. For small torches, hydrogen is often produced, along
with oxygen, by electrolysis of water in an apparatus which is connected
directly to the torch.
MAPP gas is a registered product of the Dow Chemical Company. It is
liquefied petroleum gas mixed with methylacelylene–propadiene. It has the
storage and shipping characteristics of LPG and has a heat value a little less
than acetylene.
Oxygen is not the fuel: It is what chemically combines with the fuel to
produce the heat for welding. This is called 'oxidation', but the more general
and more commonly used term is 'combustion'. In the case of hydrogen, the
product of combustion is simply water. For the other hydrocarbon fuels,
water and carbon dioxide are produced. The heat is released because the
molecules of the products of combustion have a lower energy state than the
molecules of the fuel and oxygen.
Oxygen is usually shorted to 'oxy' for use in the term 'oxy-acetylene
torch'. Oxygen is usually produced elsewhere by distillation of liquefied air
and shipped to the welding site in high pressure vessels (commonly called
'tanks' or 'cylinders') at a pressure of about 21000 kPa (3000 lbf/in² = 200
atmospheres). It is also shipped as a liquid in Dewar type vessels (like a large
Thermos jar) to places that use large amounts of oxygen.
It is also possible to separate oxygen from air by passing the air, while
under pressure, through a zeolite sieve which selectively absorbs the nitrogen
and lets the oxygen (and argon) pass. This gives a purity of oxygen of about
93%. This works well for brazing.
Apparatus
The apparatus used in gas welding
consists basically of a torch, two pressure
regulators and twin flexible hoses. The
torch is the part that the welder holds and
manipulates to make the weld. It has two
valves and two connections, one each for
the fuel gas and the oxygen, a handle for
the welder to grasp, a mixing chamber
Two types of oxy-gas torch head
82
where the fuel gas and oxygen mix, and a tip where the flame issues from.
The regulators are attached to the fuel and to the oxygen sources. The
oxygen regulator is attached to the oxygen tank and drops the pressure from
about 21000 kPa (3000 lbf/in² = 200 atmospheres) to a lower pressure for the
torch. This pressure can be adjusted to suit the job at hand by turning a knob
on the regulator, and can be set from 0 to about 700–1400 kPa (100–200
lbf/in²). Likewise the fuel regulator is attached to the fuel source and drops
the pressure to a level for the torch to use. For acetylene this is 0 to 100 kPa
(15 lbf/in²).
The flexible hoses connect from the regulators to the torch and carry
the fuel gas and the oxygen. The fuel gas connections have left hand threads
and the oxygen connectors have right hand threads so that the two cannot be
interchanged, so as to help prevent accidents.
The welder wears goggles or a shield with a shaded lens to protect his
eyes from glare and flying sparks and splatter, and wears leather gloves to
help protect his hands from burns. He should also wear clothes and shoes
appropriate for welding. Sunglasses are not adequate.
Note that the procedures and equipment used for gas welding are
essentially the same as for gas brazing.
]
Setting up the equipment
When using fuel and oxygen tanks
they should be fastened securely to a wall,
a post or a portable cart in an upright
Oxygen Rich Butane Blow Torch Flame
position. An oxygen tank is especially
dangerous for the reason that the oxygen is
at a pressure of 21 MPa (3000 lbf/in² = 200 atmospheres) when full and if the
tank falls over and the valve strikes something and is knocked off, the tank
will become an unguided and unpredictable missile powered by the
compressed oxygen. It is for this reason that an oxygen tank should never be
moved around without the valve cap screwed
in place.
Never lay the acetylene tank down
while being used, as the acetone would start
Fuel Rich Butane Blow Torch Flame
to come out through the valve. If it was laid
down while being transported, it must be set upright, valve on top.
After the oxygen tank is securely fastened, remove the valve cap. With
the valve opening pointed away from the welder, open the valve slightly for
just a moment and then close it. This serves two purposes. For one, it blows
83
out any dirt or dust that may have settled in the valve. This dirt would
otherwise end up in the regulator and shorten its life and accuracy. For
another, when a tank is filled, the worker has a tendency to tighten the valve
securely to make certain it is closed completely. It is better to break it loose
now than when the regulator is in place. Attach the oxygen regulator and
tighten the nut. Never use pliers, as the pliers will soon damage the brass nut;
always use a wrench. Also, there is a tendency of welders to over tighten the
nut. If it is not leaking, then it is tight enough. If a great amount of torque is
needed to stop it leaking, or if it will not stop leaking in spite of any amount
of tightening, then there is something wrong with the nut, the gasket or the
valve.
Attach the fuel regulator to the fuel tank in the same manner. The nut
on the fuel regulator usually has left hand threads.
Attach the flexible hoses from the regulators to the torch. The oxygen
hose is usually colored green and the fuel hose red. The fuel hose has left
hand threaded connectors at both ends and the oxygen has right hand
threaded connectors.
With the valves on the torch closed, and the knobs on the regulators
screwed out until loose (0 setting), open the valves on the fuel and oxygen
tanks. Open the oxygen valve slightly and then wait while the high pressure
gauge on the regulator stops rising. Then open the valve fully, until it stops
turning. This is a back stop valve. Turning the valve all of the way out
prevents leakage through the packing of the valve.
Open the fuel valve also. Only open an acetylene valve one quarter
turn. This helps prevent the acetylene from being drawn off too quickly. If
acetylene 'bubbles' too rapidly from the acetone, it might become unstable.
Open the valve on a LPG tank out completely as on an oxygen tank and for
the same reasons.
If there are any leaks in the connections, regulators or torch, or any
other faults with the equipment, a safety hazard exists. The equipment should
not be used.
Never oil an oxygen regulator. It will cause a fire or explosion — solid
brass regulators can be blown apart from the force. Keep oxygen away from
all combustibles.
The flame
After this preparation, set the regulators at the desired pressure. For
acetylene, this should never be more than 103 kPa (15 lbf/in²). To prevent a
large yellow, sooty flame when first lighting the torch, open both the fuel and
the oxygen valves (more fuel than oxygen), and light a flame with a 'striker'
84
or by some other means. After the flame is adjusted to the proper size, open
the oxygen valve and adjust it to give the desired balance of fuel and oxygen.
Usually a neutral flame is used: this is a flame where the fuel and oxygen
supplied to the torch tip are both completely combined with each other. An
oxidizing flame has an excess of oxygen and a reducing flame has an excess
of fuel (carbon). An oxidising flame is used for cutting and a reducing flame
is used for annealing e.g. to soften steel sheet metal.
An acetylene flame (as is characteristic of most fuel/oxygen flames)
has two parts; the light blue to white colored inner cone and the blue colored
outer cone. The inner cone is where the acetylene and the oxygen combine.
The tip of this inner cone is the hottest part of the flame. The outer cone is
where hydrogen and carbon monoxide from the breakdown of the acetylene
and partial combustion of the inner cone combine with the oxygen in the
surrounding air and burns.
A neutral flame has a well defined inner cone. A reducing flame has a
feathery inner cone. An oxidizing flame has a smaller inner cone that is
sharply defined and is pale blue. The welder observes this while adjusting the
fuel and oxygen valves on the torch to get the correct balance for the job at
hand. There is also a difference in the noise the flame makes. Adjusting the
flame is not a hard thing to do after a little experience and practice.
The size of the flame can be adjusted to a limited extent by the valves
on the torch and by the regulator settings, but in the main it depends on the
size of the orifice in the tip. In fact, the tip should be chosen first according to
the job at hand, and then the regulators set accordingly.
The flame is applied to the base metal and held until a small puddle of
molten metal is formed. The puddle is moved along the path where the weld
bead is desired. Usually, more metal is added to the puddle as it is moved
along by means of dripping metal from a wire ("welding rod" or "filler rod")
into the molten metal puddle. The force of the jet of flame issuing from the
torch tip helps to manipulate the puddle. The amount of heat can be
controlled by the distance of the flame from the metal. There should be a
bright, incandescent spot on the molten puddle. When the puddle is correctly
maintained, a sound weld will result.
85
The blowtorch
A blowtorch is a special type of
gas welder. It has an additional lever on
the handle that, when squeezed, supplies
an extra flow of oxygen out of a center
hole in the mouthpiece. When the steel is
heated to its melting point, the extra flow
of oxygen will burn (oxidise) the molten
iron and blow it away, effectively cutting
the steel. The word "blowtorch" is often
used loosely to mean any sort of oxy-gas
torch.
An old-fashioned kerosene blowtorch
After reading activity
Match each term with its meaning
1. acetylene
2. oxygen
3. hydrogen
A. A flammable fuel gas composed of carbon and hydrogen
having the chemical formula C2H2.When burned with
oxygen, it produces a hot flame, having a temperature
between 5700°F and 6300°F. It is a colorless gas, having a
disagree-able odor that is readily detected even when the gas
is highly diluted with air. When a portable welding outfit, it is
obtained directly from the cylinder. In the case of stationary
equipment, it can be piped to a number of individual cutting
stations.
B. A chemical element with the chemical symbol O and
atomic number 8. It is the second most common element on
Earth, composing around 49% of the mass of Earth's crust and
28% of the mass of Earth as a whole, and is the third most
common element in the universe. On Earth, it is usually
covalently or ionically bonded to other elements.
C. A chemical element in the periodic table that has the
symbol H and atomic number 1. At standard temperature and
pressure it is a colorless, odorless, nonmetallic, univalent,
tasteless, highly flammable diatomic gas (H2). With an
atomic mass of 1.00794 g/mol, it is the lightest element. It is
also the most abundant, constituting roughly 75% of the
universe's elemental matter
86
4. acetone
D. In chemistry, (also known as propanone, dimethyl ketone,
2-propanone, propan-2-one and β-ketopropane) it is the
simplest representative of the ketones. It is a colorless mobile
flammable liquid with melting point at −95.4 °C and boiling
point at 56.53 °C. It has a relative density of 0.819 (at 0 °C). It
is readily soluble in water, ethanol, ether, etc., and itself
serves as an important solvent. The most familiar household
use of it is as the active ingredient in nail polish remover. It is
also used to make plastic, fibers, drugs, and other chemicals.
5. aluminum E. A silvery and ductile member of the poor metal group of
chemical elements. In the periodic table it has the symbol Al
and atomic number 13. It is found primarily in the bauxite ore
and is remarkable for its resistance to corrosion (due to the
phenomenon of passivation) and its light weight. It is used in
many industries to manufacture a large variety of products
and is very important to the world economy. Structural
components made from this metal and its alloys are vital to
the aerospace industry and very important in other areas of
transportation and building.
6. carbon
F. A chemical element in the periodic table that has the
symbol C and atomic number 6. An abundant nonmetallic,
tetravalent element, it has several allotropic forms. It occurs in
all organic life and is the basis of organic chemistry. This
nonmetal also has the interesting chemical property of being
able to bond with itself and a wide variety of other elements,
forming nearly ten million known compounds. When united
with oxygen it forms carbon dioxide, which is vital to plant
growth. When united with hydrogen, it forms various
compounds called hydrocarbons which are essential to
industry in the form of fossil fuels.
7. oxy-gas
G. A blowtorch has several meanings, which deal with tools
torch
that consume fuel. It may mean a cutting torch, a handheld
torch used for cutting metal.
8. natural gas H. Commonly referred to as gas, is a gaseous fossil fuel
consisting primarily of methane. It is found in oil fields and
natural gas fields, and in coal beds. When methane-rich gases
are produced by the anaerobic decay of non-fossil organic
material, these are referred to as biogas. Sources of biogas
include swamps, marshes, and landfills (see landfill gas), as
well as sewage sludge and manure by way of anaerobic
digesters, in addition to enteric fermentation particularly in
87
cattle.
Speaking
True or false?
1. The only used fuel gas in oxy-fuel welding is acetylene.
2. 'Oxidation' and 'combustion' are two terms which mean one and the same
process.
3. Oxygen is the best fuel in oxy-fuel welding.
4. The blowtorch has two valves and one connection.
5. The welder wears goggles to protect his hands from burns.
6. The procedures and equipment used for gas welding and gas brazing are
different.
7. When setting up the equipment, the valve cap is removed before the
oxygen tank is fastened.
8. Both pliers and a wrench are used to tighten the nut of the regulator.
9. Sunglasses can be used instead of goggles to protect eyes from sparks and
splatter.
10. The size of the flame depends on the size of the orifice in the tip and can
be adjusted by the valves on the torch and by the regulator settings.
Answer the following questions:
1. What are the other two names of the oxy-fuel welding process?
2. What does the high temperature needed to melt the metal obtained by?
3. Is acetylene always shipped to the welding site in containers?
4. Why is hydrogen useful for underwater welding?
5. How can hydrogen be produced for small torches?
6. How is oxygen delivered to the welding site?
7. What does the apparatus used in gas welding consist of?
8. What colour are the oxygen and fuel hoses?
9. What is a neutral flame?
10. How many parts does an acetylene flame have?
Use the plan to make a report about gas welding:
1. Difference between Oxy-fuel welding and oxy-fuel cutting.
2. Fuel gases used for gas welding.
3. Parts of the apparatus used in gas welding.
4. Rules of setting up the equipment
88
5. Regulating the flame.
Writing
Translate the following sentences from Russian into English:
1. Контактная сварка осуществляется нагревом или расплавлением
металлов при прохождении электрического тока в месте контакта
сдавливаемых изделий. Выполняется сжатием листовых заготовок
между стержневыми электродами (точечная контактная сварка) или
вращающимися роликами (шовная контактная сварка) либо прижатием
торцов изделий (стыковая контактная сварка).
2. Дуговая сварка (электродуговая сварка) - вид сварки, при которой
кромки свариваемых металлических частей расплавляют дуговым
разрядом между электродом и металлом в месте соединения.
3. Электронно-лучевая сварка - сварка расплавлением материалов в
месте их соединения пучком электронов с энергией до 100 кэВ.
Выполняется в вакууме. Применяется для прецизионной сварки, сварки
изделий из особо чистых, разнородных или тугоплавких металлов
(например, в микроэлектронике).
4. Газовая сварка - способ сварки металлических изделий с помощью
газового пламени, образованного при сгорании смеси горючего газа
(ацетилена, водорода, паров бензина и др.) с кислородом. Применяют
для сварки тонкостенных изделий из стали, цветных металлов и
сплавов, для наплавки твёрдых сплавов при ремонтных работах.
5. Электрошлаковая сварка - сварка плавлением металлов в месте
соединения. Источником нагрева металла служит теплота, которая
выделяется при прохождении электрического тока через расплавленный
шлак, находящийся в зазоре между соединяемыми деталями.
6. Печная сварка (кузнечная, горновая) - соединение пластическим
деформированием (например, с помощью молота) металлических
изделий, нагретых в печах или горнах.
7. Диффузионная сварка - производится сдавливанием предварительно
нагретых (без расплавления материалов) соединяемых деталей в
вакууме, в результате чего происходит диффузия атомов материалов
контактирующих деталей. Используют для сварки изделий из
трудносвариваемых металлов, неметаллов, пластмасс.
8. Термитная сварка - технологический процесс, при котором зазор
между соединяемыми деталями, предварительно нагретыми до 400 —
700°C, заполняется металлическим расплавом, полученным при
89
сгорании термита. Используется для сварки проводов, труб, рельсовых
стыков.
9. Газопрессовая сварка, соединение встык стержней, труб, фасонных
профилей и т. д. нагревом мест сварки газовым пламенем до оплавления
или пластического состояния металла и последующим сжиманием
(осаживанием) соединяемых частей.
10. Высокочастотная сварка, сварка, при которой кромки свариваемых
деталей нагревают токами ВЧ до их размягчения или оплавления и
сжимают. Ток в изделии наводится индукционным или контактным
способом. Используют, например, для сварки труб из ленты.
PART 5. MODERN DEVELOPMENTS
Lead-in
Prior to reading text, say if the method described below is a conventional
one. What makes it conventional/unconventional?
Why does this welding process best fit for aluminium and its alloys?
What should be changed in the parameters when shifting from welding
aluminium to steel?
Vocabulary
ductile
threaded
pin
shoulder
debris
shrinkage
solute
гибкий, ковкий, поддающийся обработке
с резьбой, нарезной
цапфа
буртик; поясок
осколки, обломки; обрезки; лом
усадочная деформация
растворенное вещество, раствор
Find the English equivalent sin the text for the following Russian words and
word combinations:
Традиционные технологии сварки, нагрев при трении, выработка
теплоты
(тепловыделение),
инструментальная
оснастка,
в
деформированном состоянии, нержавеющая сталь, шестивалентный
хром, зона термического влияния, накаленный докрасна, механическая
обработка, элемент конструкции.
90
Reading
Text 1. Friction Stir Welding (FSW)
H.H. Bhadeshia
Friction stir welding, a process invented at TWI, Cambridge in 1991,
involves the joining of metals without fusion or filler materials. It is used
already in routine, as well as critical applications, for the joining of structural
components made of aluminium and its alloys. Indeed, it has been
convincingly demonstrated that the process results in strong and ductile
joints, sometimes in systems which have proved difficult using conventional
welding techniques. The process is most suitable for components which are
flat and long (plates and sheets) but can be adapted for pipes, hollow sections
and positional welding. The welds are created by the combined action of
frictional heating and mechanical deformation due to a rotating tool. The
maximum temperature reached is of the order of 0.8 of the melting
temperature.
The tool has a circular section except at the end where there is a
threaded probe or more complicated flute; the junction between the
cylindrical portion and the probe is known as the shoulder. The probe
penetrates the work piece whereas the shoulder rubs with the top surface. The
heat is generated primarily by friction between a rotating-translating tool, the
shoulder of which rubs against the work piece. There is a volumetric
contribution to heat generation from the adiabatic heating due to
deformation near the pin. The welding parameters have to be adjusted so that
91
the ratio of frictional to volumetric deformation--induced heating decreases
as the work piece becomes thicker. This is in order to ensure a sufficient heat
input per unit length.
The microstructure of a friction-stir weld depends in detail on the tool
design, the rotation and translation speeds, the applied pressure and the
characteristics of the material being joined. There are a number of zones. The
heat-affected zone (HAZ) is as in conventional welds. The central nugget
region containing the onion-ring flow-pattern is the most severely deformed
region, although it frequently seems to dynamically recrystallise, so that the
detailed microstructure may consist of equiaxed grains. The layered (onionring) structure is a consequence of the way in which a threaded tool deposits
material from the front to the back of the weld. It seems that cylindrical
sheets of material are extruded during each rotation of the tool, which on a
weld cross-section give the characteristic onion-rings.
The thermomechanically-affected zone lies between the HAZ and
nugget; the grains of the original microstructure are retained in this region,
but in a deformed state. The top surface of the weld has a different
microstructure, a consequence of the shearing induced by the rotating toolshoulder.
The Machine
This is a picture of a friction stir welding (FSW
shows a typical) machine. This one is at the Joining
and Welding Research Institute (JWRI) of Osaka
University, Japan.
The Tool
Friction-stir welding
machine
An illustration of some types of tools. Each
tool has a shoulder whose rotation against the
substrate generates most of the heat required for
welding. The pin on the tool is plunged into the
substrate and helps stir the metal in the solid state.
92
The Fixture and Weld
The two halves to be joined must be rigidly fixed before the welding
operation (first picture below). The pin, which is an integral part of the tool,
is plunged into the metal to help stir it up; the shoulder of the tool generates
much of the heat. As the weld is completed, the tool is withdrawn leaving
behind a hole. The weld is designed so that such regions can be discarded
from the component. The presence of a hole may not be appropriate when
welding pipes or storage vessels. The hole can be avoided by designing the
tool such that only the pin can be retracted automatically and gently into the
shoulder, leaving behind an integral weld.
FSW of Steel
Steel can be friction stir welded but the essential problem is that tool
materials wear rapidly. Indeed, the wear debris from the tool can frequently
be found inside the weld. The process would therefore be used in special
circumstances where other welding methods are inadequate. These
circumstances have yet to be clarified. There are so many good methods by
which steel can be welded. The example below is the FSW of 316L stainless
steel. Notice that the sample becomes red-hot during welding.
93
Since the tool gets red hot, it is necessary to protect it against the
environment using a shielding gas. A possible use of FSW in the welding of
steels is in the context of stainless steels. Austenitic stainless steels can easily
be welded using conventional arc welding and other processes. However,
FSW can offer lower distortion, lower shrinkage and porosity. More
important is the avoidance of fumes containing hexavalent chromium which
is carcinogenic. In addition, chemical segregation effects associated with
welding processes involving solidification are avoided. Such segregation can
lead to a degradation of corrosion resistance since electrochemical cells are
set up between solute-rich and poor domains.
Friction Stir Welding of Cast Aluminium Alloy
The most popular aluminium casting-alloy contains about 8 wt% of
silicon. It therefore solidifies to primary aluminium-rich dendrites and a
eutectic mixture of aluminium solid-solution and almost pure silicon. The
latter occurs as coarse silicon particles which tend to be brittle. The cast alloy
usually has some porosity. Friction stir welding has the advantage that it
breaks up the coarse silicon particles and heals any pores by the mechanical
processing, as illustrated below.
94
A section through a friction stir weld made in an Al-Si casting alloy.
There are pores indicated in the base metal (BM). HAZ represents the heat
affected zone, TMAZ the thermomechanically affected zone, and SN the stir
nugget. The photographs in this section have kindly been provided by
Professor H. Fujii of JWRI, Japan.
Optical micrographs of regions (a), (b) and (c) of the stir nugget. The location
95
of these regions is identified in macroscopic section presented above.
Optical micrographs showing the microstructure in (a) the base metal; (b)
heat-affected zone; (c) the thermo mechanically affected zone, where
considerable refinement of the silicon has occurred.
Tensile strength Proof
stress Elongation (%)
Fracture local
(MPa)
(MPa)
Joint 150
85
1.6
BM
Weld 179
87
5.3
TMAZ
SN 251
96
14.4
SN
The refinement of silicon and elimination of porosity leads to better
mechanical properties in the weld than in the base plates.
True or false?
1. FSW is not used to weld steels.
2. It’s impossible to avoid holes in welds made by FSW method.
3. The maximum temperature reached during FSW is above the melting
temperature.
4. The characteristics of the material being joined affect the microstructure of
a friction-stir weld.
5. FSW is the only method for welding austenitic stainless steels.
6. Pipes can be welded using FSW.
Translate the following sentences into English:
1. При сварке трением присадочный металл не используется.
2. Получаемые в результате сварки трением швы отличаются
прочностью и пластичностью.
3. Шов при сварке трением образуется в результате нагрева при трении
инструмента о свариваемую деталь и возникновения механической
деформации.
4. Микроструктура шва, полученного при помощи сварки трением,
определяется целым рядом параметров.
5. Поверхность шва внешне похожа на луковые кольца.
6. Наличие или отсутствие поры в зоне шва определяется конструкцией
инструментальной оснастки и скоростью отвода инструмента.
7. Пары шестивалентного хрома являются канцерогенными.
8. Использование сварки трением позволяет снизить усадочную
деформацию и пористость.
96
9. Существенным недостатком данного метода является быстрый износ
инструмента.
10. При сваривании стальных конструкций сталь раскаляется докрасна.
Make a short description of the method using the following key words:
Fusion, filler material, aluminium and its alloys, plates and sheets, frictional
heating and mechanical deformation, rotating tool, tool, shoulder, pin, work
piece, heat generation, microstructure of a friction-stir weld, applied pressure,
characteristics of the material, withdrawal of the tool, onion-ring structure,
HAZ, integral weld.
Vocabulary
hermal (heat) ageing
bending test
tensile (tension) test
HAZ
butt joint
Abutment
Backing
термостарение
испытание на изгиб
испытание на растяжение
heat affected zone зона термического влияния
стыковое соединение; соединение встык
торец; упор; опора,
опора
Reading
Read the text below and say what new facts you learn from it.
Text 2. New Welding Method for Aluminium
Friction welding has been used in the manufacture of rotating bodies
since 1956 and has become well-known as an extremely rapid and reliable
method. Unfortunately, its use has been limited to rotationally symmetrical
bodies, as friction welding is based the principle of rotating two workpieces
at high speed in relation to one another and then pressing them against once
another with great force, thereby rapidly obtaining forging temperatures. As
this method makes high productivity possible, the opportunity to use friction
welding for other types of object has been eagerly awaited for many years.
Aluminium is normally welded using MIG, TIG, plasma or manual
welding with coated electrodes. A new welding method, Friction Stir
Welding, has been developed for welding aluminium. This method has been
patented and developed by TWI. The necessary expertise has been acquired
97
in a sponsorship project which has been run by TWI in collaboration with
possible users and machine-builders.
In principle, the method is based on obtaining a sufficiently high
temperature to forge two aluminium components, using a rotating tool which
moves along the joint. The temperature is under the melting point of
aluminium.
The aluminium components which are going to be joined are clamped
to a TIG using a powerful fixture. A tool with a cylindrical shoulder and with
a special profile is positioned above the centre line of the joint. The tool is
rotated at at a peripheral speed and is pushed into the material with great
force. The material comes plastic as a result of the frictional heat and is
forced to rise around the rotating probe until the shoulder of the tool comes
into direct contact with the surface of the aluminium. When the tool is moved
along the joint, the material is plasticised by the frictional heat of the front of
the rotating probe and moves behind the probe, thereby forming a weld. This
process continues as long as the tool is moved along the joint.
The Friction Stir Welding of alumimium 60 82 -T6 or SS 4212-06 has
been shown to produce high strength values. Typical values for the ultimate
strength across joint are in the range of 211-230 N/mm2, without ageing.
Higher strength can be obtained by thermal ageing. The specification for the
base material is a minimum of 290 N/mm2. Bending tests and tensile tests
have been conducted without any negative observations. Fractures took place
in the base material HAZ.
Thick material. When welding materials оf more than 15 mm, the
welding is done from both sides. The maximum thickness is around 30 mm at
100% penetration. The welding speed is approximately 180 mm/min.
Welding speed. The welding speed depends on the dimensions and the
alloys which are used. The spindle speed also affects the welding speed. For
example, the welding speed in material 5 mm thick can be 610 mm/min with
a 60 82-T6 alloy.
Joint types. Butt joints and lap joints can be welded. Corner joints and
other special joints can also be welded, but the method, accessibility,
complete penetration requirements and so on must be taken into account
when they are planned.
Welding data. In Friction Stir Welding, the welding parameters are
dependent on the aluminium alloy, the dimensions, the speed of the spindle
and the traveling speed. In addition, the design of the tool has an important
effect on the welding result. Work on all these parameters is in progress with
the aim of building up data bank for the progress in order to facilitate the use
of Friction Stir Welding.
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Working Environment. The working environment is improved
dramatically when Friction Welding is used. Welding flash, fumes and ozone
formation are totally eliminated. Steel brushing and interpass cleaning are
also unnecessary.
Advantages
The advantages of the method are:
High, consistent quality.
Material thickness from 1.6-15 mm can be welded as single-pass procedures.
Material from 15-30 mm can be welded on both sides.
No joint preparation, only degreasing.
No grinding or brushing.
No consumables.
No shielding gas.
Flat surface without weld reinforcement or splatter.
No magnetic blowing as the welding is done without an arc.
Environmentally-compatible method without flash, fumes or ozone
formation. Less risk of pores and cracking as the temperature never reaches
the melting point of aluminium.
No burning off of alloy substance as the temperature never reaches melting
point.
Alloys which are difficult to weld can be welded as there is only a small risk
of hot cracking. High productivity.
Disadvantages
The method can only be used on straight, flat workpieces or hollow
profiles with an abutment or backing. The method requires a stable welding
machine with good reproducibility. Powerful fixture which is able to hold the
components in the correct position throughout the welding operation. The
back of the object must be accessible if 100% penetration is necessary. As the
method requires a stable welding machine with a powerful fixture, the
welding equipment should preferably be stationary. This welding method
leaves an end hole when the tool is pulled away from workpiece. In many
cases, this hole can be cut off, but, in other cases, it has to be sealed using
another method.
Applications
Suitable applications include extruded aluminium profiles for:
shipbuilding; offshore platforms; railway wagons, trams and underground
train carriages; the automobile, brewing, defense industries; production of
electric motors, cooling elements.
99
Summary
Friction Stir Welding is a new welding method which enables two
workpieces made of aluminium to be forged using friction. The method has
characteristics which make it extremely interesting for the highly-productive
joining of straight profiles and plates. In the longer term, this method will
help to extend the use of aluminium.
After reading activity
Use the words and phrases from the list below to fill in the blanks in the
sentences:
rotating bodies, manual welding, sponsorship project, necessary expertise, in
collaboration with, frictional heat, without any negative observations, build
up data bank, sufficiently high temperature, environmentally-compatible
1. … is being replaced by automatic and semi-automatic types of welding in
many applications.
2. They could buy the new equipment only thanks to a successfully realized
… .
3. … are necessary elements of friction stir welding.
4. The new project was realized … foreign partners.
5. In order for the weld to be formed … in the welding area should be
provided.
6. After the thorough repairs the equipment had been running for 2 years … .
7. The quality control supervisors had to carry out … before putting the
welding machine into operation.
8. The experience the engineers had in welding such structures helped them
… necessary for further development of the product.
9. … resulting from rotating bodies coming into direct contact can be
removed by special coolers.
10. This new welding machine is both operator friendly and … .
Speaking
Say if the following is an advantage or disadvantage of friction stir welding:
1. A hole is left on the surface after the tool is pulled away from work piece.
2. The welding machine should be powerful and stable.
3. The joint doesn’t need special preparation.
4. Flash, fumes and ozone are not formed.
100
5. Consumables and shielding gas are not required.
6. Abutment or backing is necessary.
7. Arc is not used.
Answer the following questions:
1. What is of Friction Stir Welding method based on?
2. How is the weld formed?
3. What do the welding parameters depend on?
4. What, in your opinion, are the most important advantages/disadvantages of
the Friction Stir Welding method?
5. Want is the best sphere of application of this method at present?
Writing
Write a short report about FSW according to the following plan:
1. The principle of FSW.
2. Working environment.
3. Advantages and disadvantages.
4. Applications.
Lead-in
Think of the answers for the following questions:
1. What is an automated welding system?
2. What might be the advantages of automated welding systems compared
with manual welding?
3. What part do you think can never be welded using automated welding?
Vocabulary
run
man-machine
communication
automated system
welding sequence
non-destructive testing
interpass temperature
проход
интерфейс человек-машина
автоматизированная система
последовательность сварки; порядок наложения
швов
испытания
без
разрушения
образца,
неразрушающий контроль
температура
начала
мартенситных
101
weld bead
log file
processing
превращений
наплавленный валик сварного шва
системный журнал
обработка
Reading
Text 3. Man-machine Communication for Multi-run Arc Welding
The multi-run welding of heavy components imposes special demands on
man-machine communication (MMC) for automated welding systems.
Welding sequences of several hours with limited operator surveillance
necessitate pre-programming, not only of the nominal process data, but also
of other conditions for the successful performance of the welding process in
varying external conditions. Warnings of conditions requiring the operator's
attention must be given during welding. Should a situation occur in which
the quality of the weld is jeopardized, the process must be stopped in a
controlled manner and the reason for the stop must be displayed. Upon
completion of the weld, a presentation, indicating all the important events
during the welding cycle, should be made to determine the amount of nondestructive testing. Provision should be made for further detailed
investigations of optional parts of the cycle, as well as for the storage and
documentation of the course of the process.
The operator interface for the ESAB multi-run MMC is an industrial
PC. The pre-programming modules are divided into blocks of set-up
parameters, process parameters, warnings, reports and stop limits. Different
sets of process parameters can be automatically retrieved during the welding
sequence. During welding, the screen shows the preprogrammed parameters,
the actual measured values and the way the process is progressing (e.g. layer,
bead and position).
If a warning is activated, the operator is given the choice of
immediately stopping the process stopping it after the completion of the bead
or allowing it to continue.
A small remote control box, which can be hand-held, contains the
controls the operator needs for preparing, starting and stopping the process.
The control system registers the welding sequence in two separate files, the
Weld Report and the multi-run. In the Weld Report, all the installation
parameters such as wire type and wire dimension, flux (or gas) type and
permissible inter-pass temperatures are stored, together with the specified
102
process parameters such as welding voltage, welding current and welding
speeds and their report, alarm and stop link.
All the important events during welding, such as start, stop(s), restarts,
exceeded report limits and warnings for flux level, high or low interpass
temperature, are stored in the Weld Report. All the events are stored together
with the actual date, time, weld layer, weld bead and position in the joint.
Should the event be an exceeded process parameter, the parameters at the
time in question are also stored.
In the Log File, the position and process parameters are continuously
registered (every 20 mm). A normal Log File report for a thick-walled
welding object could fill 1,000 pages.
The Weld Report provides a good overview of important events during
welding. The reported events provide valuable information for the planning
of non-destructive testing and offer easily-accessible documentation of the
welding process. If further investigations are deemed necessary, the Weld
Report constitutes a good register for entering the Log Files in which detailed
information from the sectors associated with the reported events can be
found.
The multi-run control system can also be connected to customers'
central computer systems for documentation or further processing of both
Weld Reports and Log Files, together with other quality control data.
After reading activity
Match the words and their translation:
1. operator surveillance
2. external conditions
3. operator's attention
4. in a controlled manner
5. operator interface
6. pre-programming
modules
7. set-up parameters
8. control box
9. welding voltage
10. welding current
11. welding speed
12. actual date
A текущая дата
Bсила тока при сварке
C программируемые модули
D автоматически
E внешние условия
F напряжение электрического тока при сварке
G толстостенный
H скорость сварки
I внимание оператора
J легкодоступный
K контроль со стороны оператора
L блок управления
103
13. thick-walled
14. easily-accessible
M установленные параметры
N операторский интерфейс
Answer the following questions:
1. What are the functions of the described automated system?
2. In what cases must the welding process be automatically stopped?
3. What does the system do when the weld is completed?
4. What do the pre-programming modules include?
5. What parameters are displayed on the screen during the welding process?
6. What can an operator do when he receives a warning from the automated
system?
7. What does the remote control unit contain?
8. Where are all the important events happening during the welding process
stored?
9. What is registered in the log file?
Translate the following sentences into English:
1. Использование автоматизированных сварочных систем позволяет
легко определить объем необходимого контроля качества.
2. В случае возникновения угрозы качеству сварного шва сварочный
процесс немедленно прекращается.
3. Оператор может контролировать подготовку, начало и завершение
сварочных операций с помощью пульта дистанционного управления.
4. Данные о дате, времени выполнения операции сварки, сварном слое,
наплавленном валике сварного шва сохраняются в отдельном файле.
5. Автоматизированные сварочные системы не требуют значительного
вмешательства оператора в ход сварочного процесса.
6. Информация о типе и диаметре сварочной проволоки заносится в
программу.
7. По окончании сварки на дисплее отображается вся наиболее важная
информация о ходе процесса сварки.
8. Записанные параметры представляют собой ценную информацию о
процессе сварки.
9 Данные поступают в центральную вычислительную систему для
дальнейшей обработки.
104
10. Автоматизированная сварочная система обеспечивает успешное
осуществление сварочного процесса.
Vocabulary
simulation
word processing
software
storage
CD ROM
consumable
fatigue
rod
reel of wire
parent metals
complementary
traceability
NDT
distortion
tolerance
butt joint
fillet joint
supervisor
welding fume
extraction
equipment
regulations
copper wires
to gain access
моделирование; имитация, воспроизведение
электронная обработка текста
программное или математическое обеспечение,
программные средства
хранение
Compact Disk Read-Only Memory - компакт-диск
расходные материалы
усталость (материала)
электрод
моток проволоки
основной металл
дополнительный, добавочный
отслеживаемость
nondestructive test испытание без разрушения образцов
деформация; коробление
тех. допуск, допустимое отклонение
стыковое соединение; соединение встык
шпоночное соединение
инспектор
сварочный дым, сварочные аэрозоли
вытяжное (вентиляционное) оборудование
правила, устав; нормы; инструкция
медные провода, проволока
получать доступ
While-reading activity
Find the English equivalents in the text for the following words and word
combinations:
производство, частый пользователь, растущий рыночный спрос, источник
информации по сварке, выполнять простые вычисления, новейшие
программные технологии, заметный прогресс в производстве
аппаратного обеспечения, графическая система, набор правил,
105
практический опыт, вопросы для контроля знаний, видеоряд,
круглосуточно, богатый источник информационных технологий в
области сварки, местный телефонный звонок, удобное средство связи,
набор протоколов, гипертекстовая ссылка, каталог веб-страниц,
поисковая машина, поиск технической информации, температура
предварительного подогрева, иметь доступ к персональному
компьютеру, обучающие программы, скорость обмена данными.
Reading
Text 4. IT in Welding and Cutting for the Welding Engineer –
PC Programs and the Internet
The PC has now become an essential tool in the work of the engineer for
not only word processing but also specialized tasks such as in design, simulation
and performance assessment. Within the manufacturing industry sector, most
engineers have access to a PC and the vast majority can be classed as frequent
users. It is not surprising, therefore, that in response to the growing market
demand, a wide range of computer programs have been written
specifically for the welding engineer. Whilst PC programs can be
considered to be a mature source of welding engineering IT, over the last
year the Internet has emerged as a new exciting source of welding related
information.
As the Internet is already widely used by many welding engineers as a
source of IT, guidelines are provided on how the vast amount of information
on welding engineering related topics can be accessed.
Welding engineering software for the PC
The first IT packages written for the welding engineer were for
carrying out simple calculations such as the preheat temperature level to
avoid hydrogen cracking. However, as the PC became more powerful (faster
computing speeds and additional memory), their use was extended to mass
storage of information in databases such as for welding procedures and
welder qualification. More recently, software has incorporated novel
programming techniques, expert systems for knowledge based advisory type
software and multimedia systems for advisory and education and training
software. The main advantage of expert systems is that they are capable of
encapsulating expert knowledge, which may be largely subjective. Thus,
operation of an expert system differs from that of a conventional software
which progresses in a predetermined, step by step manner until a result is
obtained e.g. the preheat temperature or the output of a database.
106
Interrogation of a problem solving expert system will produce an output,
which is usually advice or an opinion as to the likely cause of the problem
and the recommendations to avoid the problem in the future.
A noteworthy advance in computer hardware in recent years has been
the inclusion of a CD ROM player in the PC to provide a multimedia
capability. Multimedia combines scanned photographs, graphics, animation,
audio and video action with very fast processing and large databases to
provide very visual / interactive software.
T
he CD ROM disk is crucial in that with a capacity of 700MB can store
over 250,000 pages of text, or up to 30 mins of video, equivalent to 450 high
density 3.5 in floppy disks.
Commercially available software for the welding engineer
There is now a wide range of powerful software available to the
welding engineer which makes best use of the computing, memory,
knowledge based and/or multimedia facilities of the PC. The IT programs
produced as aids for the welding engineer can be conveniently grouped into
the following categories:
► Repetitive calculations;
► Storage of Information;
► Interpretation of Standards;
► Advisory;
► Simulation;
► Education and Training.
Many companies have written software for in-house use but the
examples described here have been restricted to commercially available
software.
Repetitive Calculations
This group was the first type of software written specifically to help
the welding engineer carry out routine or time consuming calculations.
Topics include the calculation of weld volume, consumable requirements,
cost of fabrication and design calculations for fatigue service. WELDVOL is
typical in that it will allow the user to calculate the volume of weld metal to
be deposited and from this information, the number of rods, or reels of
wire, to be purchased. The program can accommodate a range of arc
processes, joint types and parent metals.
107
Storage of Information
XWELD is a welding procedure management system. The system is a
multi-user relational database and has the following advantages over a paper
based document control system:
► Integrated drawing system and graphics library;
► Electronic distribution of procedures;
►Search functionality for all essential variables of the procedure;
QMWELD is a complementary program for management of
fabrication information for ensuring that a fabrication is completed on time
and to an appropriate standard. The system gives full traceability with NDT
records.
Interpretation of Standards
FATIGUEWISE is based on BSI 7910 (formally PD 6493),
"Guidance on Methods for Assessing the Acceptability of Flaws in Fusion
Welded Structures". The software allows analysis of structures, for safety
critical applications, using either the fracture procedures or the general
fatigue procedures.
FATIGUEWISE is a typical software for interpreting a standard
which is a complex text procedure. A set of rules derived from the standard
are embedded in the software ensuring that each time an assessment is
made the standard is applied equally rigorously. As most assessments
require numerous calculations, the software will save the user both time and
costs especially when carrying out a sensitivity or critical analysis by varying
one of the input parameters.
The use of a friendly graphical interface ensures that the user is only
asked for information specific to the current assessment.
Advisory
STAYING IN SHAPE is an expert/multimedia system that provides
practical advice and training on how to overcome the problem of
distortion caused by welding and cutting operations. The information is
based on expert knowledge and practical experience. Multimedia (video,
animations, audio, scanned photographs and graphics) is used to facilitate
the transfer of knowledge and learning.
The knowledge contained in the system includes:
► The different types of distortion and when they occur;
► The factors in welding affecting distortion;
► Practical steps to reduce distortion;
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► Precautions for specific welding and cutting situations;
► Actions to correct distortion after welding.
The system also includes a series of quiz type questions that will test
the user's understanding of distortion.
Simulation
MAGSIM simulates the GMA welding process calculating the weld
shape and the thermal cycle at various points along the weld (7). Graphics is
used to display the cross section of the weld and a 3-D view is used to
visualize the simulation results; the calculated thermal cycle and shape of
the weld pool. The program can be used to predict the weld quality for
selected welding parameters with tolerances. For butt and fillet joints in
СMn and alloy steels, welding parameters can be optimized for a specific
task.
Education and Training
WELDING FUME TUTOR is a CD ROM based multimedia training
course aimed at educating welders, supervisors and welding engineers on
the risks to health that could arise from inhalation of welding fume. The
program can also be used for training welders in fume control techniques
and use of extraction equipment. The information contained is based on
statutory regulations, expert knowledge and practical experience. The
program is interactive and combines video clips, animated sequences, audio,
scanned photographs and graphics.
Welding engineering IT and the Internet
The Internet is unique in that it contains a vast store of information
which is readily available to engineers 24 hours a day. Its potential as a
source of IT for welding engineers has yet to be fully realized. In order to
realize this potential, welding engineers must have knowledge of:
► The Internet System;
► World Wide Web (WWW)
► Hardware Requirements
► Accessing and Searching the WWW
The Internet System
The Internet is not a single computer but a network of millions of
computers linked by a telecommunication system (copper wires, fibre optic
cable and satellites). In simple terms, the Internet can be considered a
world-wide array of computer networks linked by the telephone.
109
Information is stored on the computers which are called "servers".
Servers connected to each other form "local networks" and the networks
connected together form the "inter-network" or Internet. The "client" is a
computer that allows user access to information services over the network.
Hardware Requirements
The hardware requirements for accessing the Internet are:
► PC
► Modem
► Internet service account
► Telephone line
The standard PC, costing typically £1000, is suitable for connecting to
the Internet but a modem will be required; the modem is a device which
allows a computer to transmit and receive data via the telephone. Modems
are increasingly being fitted to the PC as a standard feature but it is
recommended that for efficient communication, the modem should be
capable of a data exchange rate of at least 33.6kbs.
Electronic post or e-mail
Electronic or e-mail is widely used as the user can send and receive
messages from anyone in the world who has an Internet compatible e-mail
address e.g. [email protected] The advantages of the e-mail are that the
messages cost no more than a local telephone call and are stored on the
recipient's computer until he is ready to look at his mail. E-mail is a useful
means of communication for engineers in that, in addition to messages,
documents, software and video images can be transmitted.
World Wide Web (WWW)
The Internet is a physical network on which the information travels
but the "World Wide Web" or WWW is a collection of protocols (rules) and
standards used to access the information available on the Internet. Each
Web site has a unique address e.g. Esab Europe's address is
http://www.esab.se. Each document on the web site also has its own address
termed Uniform Resource Locator (URL). For example, http://www
twi.co.uk/bestprac is the URL of the document which contains technical
information from on best practice for welding "Job Knowledge for Welders";
"http" tells the browser that it is a hypertext file (Hyper Text Transfer
Protocol), and http://www.twi. co.uk is the server on which the web page is
located.
The point-and-click user interface is similar to more conventional
windows based PC programs. The protocol tells the user's computer how to
110
display the information. The hypertext links allows the user to browse
through information held either on the same server or, more importantly, on
any other computer connected to the Internet. The WWW protocol covers
most types of information, including multimedia, and the method of
communication.
Accessing and Searching the WWW
To enable a user to gain access to the Internet an account is required
with a "Service Provider". When the user logs on to the Service Provider's
server, the software will allow the user to browse the Internet accessing and
retrieving information from the various servers/web sites.
To search for particular information on the WWW, a "search engine"
is used to produce an index or a catalogue of web pages. Searching involves
simply filling in a form with words or phrases which describe the
information you require. The search engine will produce a list of Web pages
which best match the query.
Welding engineering IT on the WWW
The main use of the Internet by engineers is to search for technical
information, exchange technical data and to purchase products. Most of the
sites have hypertext links to many more sites that contain related
information on, for example, engineering, materials, manufacturing and non
destructive testing. TWI is typical of the organizations offering technical
information. The information available includes technical data sheets, "best
practice" guides, directory of suppliers, standards information, abstracts of
research projects.
The TWI Web site is accessed by over 6000 users each month and
approximately half of the users are from the USA. The most requested
pages relate to the technical information.
As advertising is freely practiced on the WWW, most commercial
companies have Web pages devoted to the advertising and marketing of
their products. The companies can make text, pictures, sounds and video
available on their Web pages using the hypertext mark-up language. The
ESAB WWW site (http://www.esab.se) contains the following PC programs
available from Business Area Consumables:
► WELDCOST - selection of welding process from
economic/productivity calculations;
► WELDOC - storage and retrieval of welding procedure
specifications;
► PREHEAT -calculation of preheat temperature;
► EQUIST -steel grades and their equivalents;
111
► STAR - stainless steel consumables;
► CONQUEST - range of steel grades and their recommended
consumables;
► THE SCHAEFFLER-DELONG—WRC'92 analysis program is
particularly useful to welding engineers and metallurgists in that it can be
used to select a suitable consumable when welding dissimilar metals, predict
the microstructure of the resulting weld, warn about possible metallurgical
risks on welding, build a database of commonly used metals and their
consumables.
A typical screen display may show the composition of the resulting
weld metal produced when welding 15 Mo 3 steel to AISI316L stainless
steel using the type OK 67.60 consumable. The diagram may also contain a
useful warning on the zones of weld metal compositions (nickel and
chromium equivalents) in which cracking is likely to occur.
After reading activity
Match the words from the left and the right columns:
1. PC
A. мультимедийные средства
2. database
B. многопользовательский
3. expert system
C. чувствительность
4. step by step
D. введенные параметры
5. floppy disk
F. волоконно-оптический кабель
6.multimedia
G. ПК
facilities
7. in-house use
H. практический совет
8. weld volume
I. объем сварочных работ
9. multi-user
J. внутреннее использование
10. sensitivity
K. критический
11. critical
L. экспертная система
12.input
M. пошаговый
parameters.
13.
practical N. гибкий диск
advice
14. fibre optic O. база данных
cable
Answer the following questions:
1. How do engineers now use a PC?
112
2. What are the two modern sources of welding related information?
3. What were the first IT packages for the welding engineer used for?
4. What did faster computing speeds and additional memory make possible
to do in the field of welding?
5. What is the difference between an expert system and conventional
software?
6. What is multimedia?
7. What is the storage capacity of a CD-ROM disk?
8. How can the IT programs produced for the welding engineer be
conveniently grouped?
9. What can XWELD, QMWELD, FATIGUEWISE, FATIGUEWISE,
STAYING IN SHAPE, MAGSIM, WELDING FUME TUTOR do?
10. Why is the Internet a unique source of information to engineers?
11. Are you an Internet user?
Translate the following sentences from Russian into:
1. Персональный компьютер стал мощным инструментом в работе
инженеров-сварщиков.
2. Многие инженеры сегодня имеют доступ к сети Интернет.
3. Компьютерные программы стали полноценным источником
информации по сварке.
4. Компьютер позволяет хранить огромное количество информации в
базах данных, выполнять вычисления, с его помощью можно повышать
квалификацию сварщика.
5. Мультимедийные программы содержат фотографии, графические и
аудио-данные, анимацию.
6. Специальные программа позволяет выполнять расчет уровня
температуры предварительного подогрева во избежание образования
трещин.
7. С помощью компьютерной программы можно рассчитать объем
металла шва, количество электродов, мотков проволоки.
8. Интерактивные программы обучения позволяют совершенствовать
знания сварщиков по различным аспектам, связанным с их
профессиональной деятельностью.
9. Все программы имеют одинаковый интерфейс "указать и щёлкнуть".
10. Большинство коммерческих компаний используют Интернет для
продвижения своей продукции.
113
Vocabulary
simulation
word processing
IT
storage
database
filing cabinet
power generation
bottleneck
моделирование
1) электронная обработка текста 2) оперативное
изготовление документов
(information
technology)
информационная
технология
хранение
база данных
1) шкаф для хранения документов; 2) картотека,
каталог
производство электроэнергии
узкое место
Reading
Text 5. Moving Weld Management from the Desk to the Desktop
Part 1. Computers as Welding Expert Systems
Welding engineers have managed welding procedures and welder
performance qualifications using computers for some years now. Engineers
now readily access vital information - no more searching through piles of
paper. They can easily develop procedures and qualifications through onscreen editing, get advance warning of expirations and produce a
professional-looking document in the end. Most fabricators now have local or
wide area networks so sharing information between key personnel is easier
than ever before. Computers can integrate management of procedures and
qualifications with production weld information and quality control (QC)
data, and so the benefits abound.
Computers have always been good at storing, sorting and searching
through large amounts of data, making them suitable for pure database
applications. Such applications have required the user to know certain
parameters, with little or no help from the software. In welding, such systems
have been used for managing welding procedures and welder performance
qualification. But, to date, most have had limited, if any, expertise in
welding.
The problem with building expertise into software it is necessary to
have a deep understanding of both software development and the technology
being computerized. In the welding industry, this includes metallurgy,
engineering, production, quality control and standards. Standards are
114
particularly important, as many aspects of fabrication are specified via
national and international standards, such as ASME IX, AWS D1.1, EN
287/288 AND ISO 9000.
Software houses with no depth of welding expertise or engineers with
no depth of software development skills both find it difficult to develop
expert welding systems. It may be possible for individual engineers to
develop software, but long-term support is difficult at best, and in most cases
impossible. For storage of large amounts of information, where considerable
time is invested in entering the data, long-term support is critical.
In addition, most existing software systems in the fabrication industry
are tools for individuals, not for large parts of organizations, because, until
recently, most organizations have simply not had the infrastructure to allow
information to be distributed electronically. E-mail has helped change this.
Electronic mail has driven most fabricators to use local and wide area
networks. These networks make it possible to share welding procedures or
welder approvals across a company via a multi-user software system.
The management of welding procedures is one of the most timeconsuming jobs of a welding engineer. Creating, verifying and approving
new procedures and checking, adapting and approving existing ones take a
ling time. Plus, searching for existing procedures for new production welds
requires expert skills. Consequently, this was one of the first welding
engineering tasks to be computerized.
The first welding procedure database management systems were
simply electronic filing cabinets. They used the speed of data sorting that
computers could offer to make searching for existing procedures much
quicker. Documents could be copied and edited to create new documents
quickly and easily. What they could not easily do, however, was help the
welding engineer create new procedures for new application.
The sources of such information are wide and disparate. They comprise
standards (welding and application), consumable and base material
handbooks, technical literature; most difficult of all to computerize is
experience. To build all this into a computer program would be impossible
without a wide knowledge of the sources available.
After-reading activity
True or false?
1. There are a lot of computer programs for welding engineers.
2. It is more important to have a deep understanding of software development
than the technology being computerized.
115
3. Most existing software systems in the fabrication industry are tools for
large companies.
3. The first database management systems could not create new procedures
for new application.
Part 2. Weldspec 4
Taking all this into account, The Welding Institute (TWI), Cambridge,
U.K., and C-spec, Pleasant Hill, California, have collaborated to develop a
new version of Weldspec. Weldspec 4 has been designed to help the welding
engineer write and draft new welding procedures while still giving the
benefits of speed and editing of existing procedures in Microsoft Windows®.
The software comes from many backgrounds, including the following:
- Worldwide welding and application standards from such organizations as
ASME, AWS, European standards and API;
- Industry practice in developing, qualifying and using welding procedures;
- Typical interactions between customer, fabricator and inspector;
- Welding engineering and metallurgy;
- Software development and knowledge representation techniques.
Software so vitally based on knowledge and recommendations from
standards needs to be frequently updated; indeed, ASME IX is updated
annually. Because anything hard coded within software is difficult to change,
Weldspec's knowledge base is stored externally to the main program so it can
be modified.
Managing welder performance qualifications (WPQs) is very similar to
welding procedures: Both are designed by standards. Variables that must be
recorded, the extent of approval given by a test and the destructive and
nondestructive examination (NDE) regimes are specified in national and
international standards.
However, unlike welding procedures, WPQs are only valid for a
specified time without practice or additional testing. Certificates expire, so
the fast sorting capability of computers is even more beneficial. By
integrating another program called Welderqual 4 with Weldspec 4 to share a
database of welder details, WPQs can be created directly from welding
procedures.
An integrated software system such as Welding Co-ordinator can help.
Welding Co-ordinator is designed to be used live to manage fabrication as it
is progressing. It is usually based around an electronic weld map, weld data
sheet or weld schedule, into which data are entered as welds are designed,
engineered, welded and tested. The weld map would also usually have some
space for approval, either weld by weld, or once a project or structure has
116
been completed. The Figure below shows a detail of a typical weld map for a
fabricator in the power generation industry.
Data are usually entered into the system from four functions, as
follows:
At the design stage, where information such as the weld ID number
and other design parameters (material type, thickness, joint type, etc.) are
entered.
At welding engineering, where a procedure is assigned. It may also be
possible to identify suitable welders or classes of welders qualified to make
the weld, although this is more likely to be done at the production stage. At
production, where the completion of a weld is registered (usually by entering
the date) and visual inspection carried out and approved.
At quality control, where acceptance of the weld is registered. This
may be simply by typing test report numbers into the system, or it may be
done with live links to electronic NDE reports.
The system also gives instant progress reporting. Anyone with access
to the system can see how fabrication is progressing. This may be simply by
looking at the weld data sheet on screen or by explicitly programmed
progress reports. These can identify bottlenecks (by, for example, comparing
the number of welds competed with the number of weld radiographed), or
help to produce reports for stage payments in large projects.
It also provides automatic assignment of welding procedures and
welder. If enough information is supplied at the design stage, the system
searches through a database of procedures for suitable welding procedure
specifications (WPSs). This may be a single WPS of a number from which to
choose from, with a click of a mouse button. Having chosen a suitable WPS,
the system searches through WPQs for qualified welders. If necessary, the
system can list welders in order of their certificate expiration dates; with
those due to expire soonest at the top of the list; so maximum benefit can be
made of extending their qualification.
The system can also produce reports on repair rates per welder (to
identify training requirements), by procedure (to highlight defect-prone
procedures) or by any other measure, providing the relevant data are
recorded.
It also automatically generates document packs on completion of a
project. A very time-consuming task manually, it's again ideally suited for
computerization. With the click of a button, the system can print the weld
maps for a project, along with all the WPSs used (with backup procedure
qualification records (PQRs) if necessary and all the WPQs, which are
updated automatically based on satisfactory production welds. In addition, if
117
NDE specifications have been used to report testing, the system can print
relevant NDE reports as well. This information can also be archived on CD.
It can also instantly trace production welds to the information backing
them up. If the inspector wants to see a WPS that was used on a weld, or
proof that the welder was suitably qualified, this can be done with the click of
a button. This can be especially useful while inspection a structure after a
number of years of service. If a defect is found, the engineer can access the
original WPS, for repair purposes, or the NDE report, to see if evidence of
the defect was present at testing.
Answer the following questions:
1. What can Weldspec 4 do?
2. What are the main sources from which Weldspec 4 originated?
3. How can Weldspec 4 be updated?
4. How is data entered into the system?
5. In what ways can the system produce reports?
6. What time-consuming tasks can Weldspec 4 perform with a click of a
button?
7. What is the difference of a usual welding software from an expert system?
8. What, in your opinion, computers will never be able to do in welding?
118
Writing
Imagine you are given a task by the head of a big welding company to make a
research and decide whether it’s worth while introducing computers into the
production process. Write a report to your boss mentioning the following
points:
- What kind of software is available for welding engineers?
- How can welders get access to welding related information?
- How can computers improve the work of welders?
- What welding procedures can be best computerized?
PART 6. ADVANCED TECHNOLOGIES AND THE FUTURE OF
WELDING
Lead-in
Think of the answers for the following questions:
1. Why can welding be necessary on board of a spaceship?
2. What kinds of welding methods, in your opinion, are good for use in
space?
3. Why is welding in space such a difficult task?
Vocabulary
instrumentation
reflecting shield
preventive maintenance
arc discharge
globular
retrofitting
deposition
оснащение инструментами, приборами,
аппаратурой,
комплект
инструментов,
аппаратура
отражающий экран
профилактическое обслуживание
дуговой электрический разряд
шаровидный, сферический, сфероидальный,
шарообразный
подгонка, настройка
осаждение
While reading activity
Match the words in italic from the text with their Russian equivalents below:
Вакуумная камера, летательный аппарат, источник тепла, космический
корабль, открытый космос, солнечная энергия, компьютерное
119
моделирование, ручной инструмент, банк данных,
материал (материал с улучшенными свойствами).
улучшенный
Reading
Text 1. Space-Age Welding:
The Past, Present and Future of Aerospace Join Processes
By B.E. Paton
April 10, 2003
On Oct. 16, 1969, astronauts performed the world's first welding and
cutting experiment in a depressurized compartment. In flight aboard the
Soyuz 6 spaceship, they tested three welding processes with a semiautomatic
Vulkan unit (see Figure below): consumable
electrode arc in vacuum, low-pressure plasma, and
electron beam welding. They studied how to weld
aluminum and titanium alloys and stainless steel.
They verified the possibility of thermal-cutting these
materials and investigated the behavior of molten
metal and features of its solidification.
This experiment convinced experts that they
could use automatic welding to produce permanent,
tight joints in space. They expanded this work with a
series of investigations conducted under short-time
microgravity conditions in flying laboratories and
space simulation test chambers. In 1973 NASA
experts conducted a flight experiment with electron
beam cutting, brazing, and welding in the Skylab orbital station.
Space welding technologies have advanced since then. In-space repair
and construction of space facilities and their equipment and instrumentation
were defined in the 1980s. Another major area identified was producing
advanced materials in space with new or improved properties using different
heat sources.
Over the years scientists and specialists had to address construction of
various experimental space vehicles, namely, orbital and interplanetary
stations, radio telescopes, antennas, reflecting shields, and helio power
generation systems - in outer space.
In addition to the original problems of assembly and erection in outer
space, as well as their view of how long these vehicles would be used and
Two
cosmonauts
conduct
preflight training of a crew with
Vulkan hardware in October
1969
120
increases in the vehicles' weight and dimensions, specialists focused more
attention on preventive maintenance and repairs.
Initial Welding Experiments
The first welding experiments conducted in space demonstrated that
arc welding processes, which were widely accepted on earth and at first were
promising, had unfavorable characteristics in space, such as unstable, weakly
constricted arc discharge; unstable globular transfer; and increased weld
porosity.
During experimental retrofitting in simulation facilities-chiefly in
space simulation chambers placed in flying laboratories-the difficulties
related to these characteristics were successfully resolved. Specialized
welding equipment and techniques also were developed for this purpose, and
the required welding consumables often were selected from those used in the
aerospace industry.
However, it was clear to space system developers that almost all
maintenance and repair of long-term flying vehicles - for which neither the
scope of work needed nor the components to be repaired and restored are
known in advance-had to be performed manually with only partial
mechanization. This increased specialists' interest in studying the possibility
of manual welding in space, which led them to consider which of the existing
welding processes to use.
Welding processes such as electron beam, consumable and
nonconsumable electrode arc in vacuum, flash-butt, hollow cathode, and
helio welding were tested in vacuum chambers and in flying laboratories at
different stages of experimental studies in the 1970s and 1980s.
Technology and material versatility and minimal power consumption
ultimately were deciding factors that led them to choose the electron beam
process. This process allowed
technicians to perform operations
that could be required to produce a
permanent joint in open space:
heating, brazing, welding, cutting,
and coating deposition.
But selecting this process
didn't solve all the problems. As
investigations
progressed,
the
number of problems, technical and
psychological,
increased.
An
Cosmonauts test an electron beam hand tool at the
Salyut 7 orbital station.
opinion existed that this process,
which involves high-accelerating voltage, the possibility of X-ray radiation
121
from the weld pool, and manipulation of a sharply focused electron beam,
couldn't be done manually.
A series of experiments in a ground-based, manned space simulation
chamber enabled the engineers to solve the key technological and hardware
issues and develop a flight sample of an onboard electron beam hand tool. In
1984 and 1986 this tool was successfully tried out on the outer surface of the
Salyut 7 orbital complex (see Figure above).
Based on new engineering systems that corrected technical parameters
and suggestions from the test engineers and crews during experiments in the
Salyut station, engineers developed a new electron beam hand tool in the
1990s. The tool passed lengthy testing at NASA's Marshall Space Flight
Center and Johnson Space Center. During testing in a flying laboratory and at
zero buoyancy, as well as in a manned space simulation test chamber in
Russia, the developers were able to solve almost all the technical and
procedural problems with the tool.
Further Aerospace Welding Exploration
Almost 40 years' experience of technology developments and their
application leads to the conclusion that in this new century, major,
complicated space work will have to be addressed. Welding technologies will
be of tremendous importance.
Such technologies are partially in place, but
further space exploration will require developing
new welding, cutting, brazing, and coating
processes. New exotic materials will be introduced
in the new century, and their processing and
joining will require completely new technologies.
A number of space operations can be performed remotely, using robots
and manipulators.
Welding in space might become widely accepted only if completely new
methods of nondestructive testing and diagnosing welded structures can be
developed. This can be supported by data banks that allow automatic
selection of the process and computer simulation.
Laser applications in space, including such hybrid processes as laser-plasma
and laser-arc welding, offer promise, especially diode lasers. Friction welding
and resistance seam-roller welding also are of interest.
Advanced space systems will continue to be developed both on the
ground and in orbit. New welding and related processes and technologies will
have an important role in those developments.
122
B.E. Paton is director of the E.O. Paton Electric Welding Institute,
Kiev, Ukraine.The E.O. Paton Electric Welding Institute is a
multidisciplinary research institute that realizes fundamental and applied
research works and develops technologies, materials, equipment and control
systems, rational welded structures and weldments, and methods and
equipment for diagnostics and nondestructive quality control. Paton also is
president of the National Academy of Sciences of Ukraine.
Speaking
True or false?
1. The world's first welding and cutting experiment was carried out in the
outer space.
2. Thermal-cutting of aluminium, titanium alloys and stainless steel is
impossible in space.
3. Only automatic welding is of importance for aerospace.
4. A flight sample of an onboard electron beam hand tool was produced as a
result of series of experiments.
5. Space welding is used for maintenance and repair purposes.
Translate the following sentences into English:
1. На борту космического корабля исследователи изучали поведение
расплавленного металла и особенности его кристаллизации в условиях
кратковременной микрогравитации.
2. Технологии космической сварки шагнули далеко вперед.
3. Одна из задач, решаемых с помощью сварки в открытом космосе, профилактическое обслуживание и ремонт оборудования космического
корабля.
4. Разнообразие используемых материалов и невысокая энергоемкость
оборудования являются решающими факторами, обусловливающими
возможность использования сварки в открытом космическом
пространстве.
5. Дальнейшее освоение космического пространства потребует
усовершенствования практически всех видов сварочных технологий, а
также резания, пайки и нанесения покрытий.
6. Специфика используемого на космических кораблях оборудования
обусловливает необходимость использования прежде всего ручной
сварки при частичной автоматизации процесса.
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7. Электроннолучевой ручной сварочный аппарат прошел успешные
испытания на орбитальном комплексе в условиях открытого космоса.
8. Использование новейших материалов в следующем столетии
потребует разработки совершенно новых технологий получения
неразъемных соединений.
The title of the text under review is “The past, present and future of
aerospace join processes”. Look through the text again and say which event
relates to:
a) the past
b) the present
c) the future
The key words from the table below will help you
The past
1969, 1973, 1980s,
1990s, verifying the
possibility of thermalcutting and welding in
space
Vocabulary
down-hand welding
celestial body
bend load
welding sequence
tensile load
pressure load
root pass
tolerance
manual welding
post-polishing
tack weld
X-ray testing
(qualification)
The present
testing in a flying
laboratory, the electron
beam process, manned
space
simulation
chamber, solving almost
all the technical and
procedural problems
The future
completely new methods
of nondestructive testing
and diagnosing welded
structures,
advanced
space
systems
development,
new
exotic materials
сварка в нижнем положении
небесное тело
нагрузка на изгиб
последовательность сварки; порядок
наложения швов
растягивающая нагрузка
сжимающая нагрузка, усилие сжатия
корневой шов, проход, сварка корневого
шва
допуск
ручная сварка
последующее полирование
прихваточный сварной шов, прихватка
рентгеновская дефектоскопия
124
high duty
clamping fixture
ASME
DIN
ID
U-shape (bend)
grinding
weld seam
filler wire
saw blade
bevelling
performance capabilities
work piece
жесткий режим
прижимное устройство
American Society of Mechanical Engineers
Американское общество инженеровмехаников
нем. Deutsche Industrie-Normen Немецкие
промышленные стандарты
inside dimensions внутренние размеры
двойной изгиб; U-образное колено, двойное
колено
шлифовка
сварной шов
присадочная проволока
1) пильное полотно; пильная лента 2)
ленточная пила; дисковая пила 3) режущий
диск
1) отточка косая 2) угол фаски 3)
фацетирование
1) возможности 2) рабочие характеристики
обрабатываемая деталь
Reading
Text 2. What Is Orbital Welding
The term Orbital-Welding is based on the Latin word ORBIS = circle.
This has been adopted primarily by aerospace and used in terms of Orbit
(noun) or Orbital (adjective) for the trajectory of a man-made or natural
satellite or around a celestial body. The combination Orbital Welding
specifies a process by which an arc travels circumferentially around a work
piece (usually a tube or pipe). The concept Orbital Welding is basically a
loosely defined term that is usually used for processes only, where the arc is
travels at least 360 degrees around the work piece without interruption.
Consequently, processes, which interrupt the full 360-weld sequence such as
for better puddle control (often used for MIG/MAG welding, using the downhand welding sequence in 2 half-circles), can not truly be called orbital
welding.
Possibilities and Limitations
From welding terminology Orbital Welding belongs to the category
semi-mechanized (TIG-) welding. Because of the need for good control of the
weld puddle, the Orbital-Welding process is only practiced with the TIG
125
process and relevant rules like selection of gases, cleanness, weldability of
specific materials and consequential mechanical strength specifications such
as tensile and bend loading, are very important.
Orbital-welding is presently used whenever the quality of the weld
joint has the highest priority. These demands are not only limited to
mechanical strength and X-ray qualification, but also to the important aspects
of the aesthetics of the weld seam. For any users a uniform, flat and smooth
root-pass is the main reason for using this process. Consequently, it is
favoured in the following areas: chemical industry, pharmaceutical industry,
bio-technology, high-purity water systems, semiconductor industry, aircraftand aerospace industry. Moreover, because of the weld joint's uniform
outside shape and almost complete absence of need for any post-polishing,
Orbital-welding is even used for bends on door-handles, hand-guards, or in
dead foot-elements for champagne-glasses! Interested applicants for this
technology should certainly note that they have to confirm a couple of
indispensable premises.
The following presents the basic rules for this process, valid for all
manufacturers and systems.
Even knowing that some competitors are announcing features, which would
potentially violate the basic physical laws of nature and knowledge,
moreover, making promises and statements which are at least detected as
impossible to meet when the welding system must work under high dutycycle production conditions. Indiscriminate and exactly defined dimensions
with tolerances must be thorough and complete. The much liked standpoint,
that the welded tubes and pipes are in accordance to DIN or ASME standards
are not acceptable criteria. These qualifications only define tolerances in
percentage to the wall thickness relating to pressure loading and not to
weldability using the Orbital-Welding-Process.
For the Orbital-Welding-Process absolute tolerance values are
necessary, and furthermore, the more complicated the application, the tighter
the tolerances must be. This means, that for an easy application like welding
a stainless steel tube of 53 x 1,5 mm, a tolerance in alignment of about 0,5
mm (about 30% of the wall thickness) can be compensated, but for much
more critical applications like welding a carbon-steel pipe of 114,3 x 3,6 mm,
the same percentage can result in unacceptable weld quality. Therefore, the
question of acceptable tolerances should be researched and defined for each
application individually.
That Orbital-Welding can be used successfully and economically is
proven by the constantly increasing number of users. Field experience has
shown that Orbital-welding can be justified based upon economic reasons
alone, where the welds can be done in squared-butt no-gap preparation
126
utilizing a single pass. With advanced digital welding systems this is possible
up to a wall-thickness of 4 mm, and with welding systems with lower
performance capabilities (limited levels, no pulse-synchronized cold-wirefeeding), up to 3 mm.
Joint preparation is simple but requires high quality with an exact
90\'b0 angle to the tube/pipe axis; a high quality saw cut is usually enough.
Of course, the joints should be deburred and cleaned out of corrosion, oil,
tinder, etc. With appropriate quality-demands, this should be even obvious
for manual welds! The tube joints will be then fit together without any visible
gap. This can be done with small autogenous tack-welds or with internal or
external clamping fixtures. For larger wall-thickness it is necessary to bevel
the weld-joints, far as possible in a U-shape. Since a very precise and
uniform root pass is important, a weld joint is prepared with an. I.D. related
and fixed bevelling-machine. Manual grinding or the use of bevelling saw
blades is not precise enough for repeatable welding results. Because an
Orbital-Welding job usually requires a lot in time and money, the Orbitalmulti-pass-welding is not used very often and only where it is strictly
recommended on quality reasons. A good qualified manual welder will, in
most cases, be faster than an Orbital-welding-system. Additionally, an
Orbital-system for multi-pass welds will be much more expensive and even
more complicated than a system without this option.
Visual inspections of the weld-seam clone can never be sufficient as
the sole criterion. Other quality controls, such as, corrosion, consistency,
mechanical strength must also be considered. Also, allowed tolerances in
contents of alloys on specific materials, such as sulphur content, can result in
significantly different welding results, even when the material code is the
same. Usually, you can expect that stainless steel materials up to 3 mm wallthickness can be done without filler-wire. For higher wall-thickness
applications, you have to decide on a case-by-case basis. In some
eventualities even carbon steel can be done without filler-material, although
it's even recommended on the thinner wall-thickness to use filler-wire in any
way.
After reading activity
Find the English equivalents in the text for the following word combinations:
противоречить законам физики, обращаться вокруг обрабатываемой
детали, иметь первостепенное значение, контроль сварочной ванны,
красивый внешний вид сварного шва, гладкий и ровный проход при
заварке корня шва, шлифовка вручную, приемлемый допуск,
127
недопустимое качество сварки, квалифицированный сварщик,
содержание серы, механическая прочность, искусственный спутник,
система высокой очистки воды, обязательное условие.
Characterize orbital welding by filling in the right side of the following table:
Parameter
Model:
Principle of the process
Description
An arc travels circumferentially
around a work piece (usually a tube or
pipe).
Category
Application areas
Limitations
Speaking
True or false?
1. Orbital Welding is a process, where the arc travels at least 360 degrees
around the work piece with some interruptions.
2. MIG/MAG welding, using the down-hand welding sequence in 2 halfcircles, refers to orbital welding.
3. Puddle control is very important for Orbital welding.
4. The number of Orbit Welding users stays the same for a long period of
time.
5. Aerospace industry is the only area of Orbital Welding application.
6. Joint preparation is not necessary.
7. Orbital-welding-system is very fast and cheap.
8. Filler-wire is used for all wall thickness applications.
Describe Orbital welding by completing the following sentences:
1. The term Orbital comes from the Latin word ORBIS and means … . 2. The
Orbital Welding is a process in which an arc travels … . 3. By category it
belongs to … . 4. It is practiced only with … . 5.Orbital-welding is presently
used in such areas as … . 6. It is used to produce … . 7. The basic rules for
this process are … . 8. Absolute tolerances in Orbital-Welding Process are
important because … . 9. Wall-thickness of 4 mm is possible … . 10. Joint
preparation includes … . 11. Orbital-multi-pass-welding is rather expensive
and its use is only justified when … . 12. Filler-wire is necessary to use only
… .
128
Additional Reading
Text 3. Welding Forges into the Future
Answers from a survey of industry leaders give valuable feeedback on the
state of welding for the year 2000 and beyond.
By Andrew Cullision and Mary Ruth Johnson
The pulse of the welding community beats strongly heading into the
21st century and overall projections for the future are generally optimistic,
but a few gray clouds roam the horizon. Those sentiments were expressed by
respondents to a recent Welding Journal survey. To get a firm feel for that
pulse of present and future conditions in the world of welding, the Editors
queried AWS Sustaining Member companies, which include producers of a
variety of welded products, providers of research and design services and
manufacturers of welding equipment, consumables and accessories.
The Editors would like to thank all those who took the time to put
down their thoughts and ideas on paper. The responses were diverse, direct
and, most of all, very interesting. Those questions and a summary of their
answers are presented below.
- Do you believe welding will be used more or less in the next
decade? If more, where do you see the growth? If less, why do you
believe so?
The majority of respondents feel welding is here to stay and will be
used more in the future, although many qualified their answers, and there
were a few dissenting voices as well. Steve Sumner, manager marketing
product development, Lincoln Electric Co., replied positively, "Welding will
continue to be used more in the future because it has proven to be a
productive and cost-effective way to join metals." He went on to speculate
that "the consumer welding market will continue to provide opportunities for
growth," with home improvement and the retail infrastructure to support it
becoming a "burgeoning market." One respondent felt that for costcompetitive reasons industry will continue to replace mechanical joining with
semiautomatic and automatic joining processes, giving a definite boost to
welding. David Landon, corporate welding engineer, Vermeer Manufacturing
Co., said, "More, because welding is the most effective way to join materials
for structural integrity. Growth will be in alternative materials such as
plastics, composites and new alloys." Phil Plotica, senior V.P., sales and
marketing North America, ESAB Welding and Cutting Products, replied,
129
"Overall, I expect welding growth will keep pace with growth in the GNP.
Some specialized segments, such as aluminum, will grow faster than others,
while the continuing developments in nonmetallic materials will slow some
segments."
The feeling that growth will be in specialized areas was repeated often.
Areas that were mentioned included welding automation, GTA welding
because of the increasing need for accuracy and precision in welding new
metals; GMA welding with mixed gas shielding; sheet metal industry;
construction industry; infrastructure repair; transportation industry; marine
structures; aerospace; and automotive, especially its use of aluminum alloys.
Some feel the growth will primarily be in countries with emerging
economies, while the growth in the United States will be relatively stagnant.
Terry O'Connell, V.P. sales and marketing, Genesis Systems Group,
commented, "The U.S. welding market is flat to declining. Growth is
expected in Mexico and other developing countries. Labor shortages in the
U.S. will contribute to a steady growth in the robotic welding market." Joe
Scott, president, Devasco International, Inc., echoed the sentiment, "Less in
the U.S. with expectations of a slight decline in the economy, as well as the
continuing transition to a service/information economy. Outside the U.S.,
growth is expected as economic stability returns to troubled regions and their
need for infrastructure grows."
The perspective of some, though, is that welding will be used less in
the future. Chris Anderson, product manager, Motoman, Inc., opined, "There
will be less welding in the next decade. The number of welded products will
remain the same, but designs will be more efficient to minimize the amount
of welding."
- Which welding process (es) will see an increase in use and which will
see a decrease in use during the next decade?
There was much speculation as to which processes would see more use
in the future, but almost unanimously the process chosen for decline was
shielded metal arc welding (SMAW). A very few speculated a decline in the
use of gas metal arc (GMAW) and gas tungsten arc welding (GTAW).
A significant group felt the continuous wire processes (FCAW,
GMAW) would experience the most use. The GTAW process was the next
most mentioned. One of the reasons stated for its increase was "the need for
high-quality work on thin materials."
Don Connell, welding engineer, Detroit Edison, stated, "Any process
that can be automated will increase." Landon also had the same perspective,
"GMAW will increase along with automation." But he also speculated,
"Low-fume generating processes will increase." The concept of increased use
130
of automation at the expense of semiautomatic operation was voiced
throughout.
The laser beam welding process was mentioned for future growth, and
the specialized process friction stir welding was also targeted for expanded
use. Other processes mentioned for increased use were resistance welding,
plasma arc welding and capacitor discharge welding.
- Do you foresee a shortage of skilled welders in your area of business
during 1999; in the next decade?
Without question, the majority of replies indicated there is a shortage
now and there will be a shortage in the future. The breakdown was 72%
consider the situation problematic now and for the long term, 14% did not see
a shortage and the remaining 14% either see no shortage now, but expect one
in the future or see a shortage for 1999, but not for the future.
John Emmerson, president, Magnatech Ltd. Partnership, made a typical
comment for those who see a far reaching problem, "There is a shortage of
skilled welders everywhere in the world, and it is only getting worse as each
year passes. Despite the fact that welding is used in virtually every industry,
it seems virtually ignored as a manufacturing science. Connecticut [the state
of location for Magnatech], for example, dropped its Vo-Tech welding
classes in 1997. In addition, population dynamics in recent years in the U.S.,
Europe and Japan indicate that the next decade will see a much smaller
number of young people entering the work force. This, by itself, will result in
fewer welders."
ESAB's Plotica had a similar take on the situation, "There is a shortage
of skilled welders now in most major market areas, and this shortage will
worsen unless substantial programs are implemented to promote welding as
an attractive career choice for young people."
Landon of Vermeer Manufacturing stated, "We have had a shortage for the
past five years. I see no turnaround, and we will not see a turnaround until the
establishment acknowledges welding as a viable career path. To meet our
immediate demands, the company has developed its own welder training
program. The company is also involved in proactive programs that make
instructors at high schools and area colleges aware of welding as a viable
career."
Connell of Detroit Edison, does not see an immediate problem, as he
encouragingly stated, "There is a renewed interest in the boilermaker's
welding program, bringing in a good influx of people. I don't foresee a
shortage in 1999." Another respondent took a contrary view, noting a
shortage of skilled welders in 1999, but projecting a leveling of demand in
the next decade.
131
J
Julio Villafuerte, director research and development, Tregaskiss, had a
slightly different perspective. "The need for plain skill welders will decrease
slightly with the slowdown of manual welding. However, the need for
welding engineers will increase dramatically as welding automation becomes
more prominent."
- Where do you see the use of welding automation heading in your
industry?
If there is any one thing to bank on for the future, it is the increased use
of automation in welding operations. There was an overwhelming affirmative
from our respondents on this point, although it was not completely universal.
The perspective of those few who did not see increased use might be
expressing an influence from their particular industry. A structural steel
fabricator mentioned the difficulty in automating for weldments that do not
have a high degree of repetitiveness and variations in fitup and joint
geometry. Another individual felt automation will not replace welding
equipment for manual operations if the equipment is developed to be fast,
safe and economical.
But by far the majority feel the same as Magnetech's Emmerson, who
stated, "We see more and more companies of all sizes automating
applications that were being done manually. Many are exploring their first
use of automation, and the declining number of skilled welders will continue
this trend." The lack of, or declining numbers of, skilled welders was
frequently mentioned as reason for the growth of automation.
Philip Winslow, V.P. sales and marketing, Hypertherm, Inc., noted
another often stated reason, "Usage will increase, primarily because of the
consistency it gives to welding and cutting operations, especially with CNC
(computer numerical control) and robotically controlled processes." Lincoln's
Sumner was emphatic in his assessment, "Automation is the single most
important growth sector in the welding industry. The drive for higher
productivity and reduced costs will keep automation at the forefront." Other
reasons for the increasing use of automation included safety and the effort to
remove the welder from tiring, repetitive conditions and long-term exposure
to fumes.
Chip Cable, president, Bug-O-Systems, isolated shipbuilding and the
trucking and railroad industries as areas that will experience growth in
automation. A fabricator of offshore steel structures has targeted automation
for heavy tubular splices, plate girders and process piping. Small companies
and job shops are anticipated to at least try robotics and CNC equipment.
132
- What are the strengths of the welding industry? What are its
weaknesses?
Although our respondents listed plenty of strengths and weaknesses for
the welding industry, Plotica of ESAB, perhaps best summed up the two most
commonly held opinions. Regarding the industry's strengths, he said, "We are
a well-established, mature industry, with a solid track record in technology
and process advancements." And as to its weaknesses, "We are not attracting
enough young people into welding careers," Plotica said. "Welding is still
perceived by many as a crude and dirty process."
While many saw the industry's maturity - the reputation of welded
components for being reliable and economical, the industry's commitment to
research and development and the dedication of its work force - as signs of its
strength, nearly as many others saw it as a weakness. They believe the
industry is set in its ways and slow to change. According to one respondent,
the industry's strength is that the people involved in it are "slow to change,
with a show me attitude." On the other side of the coin, he said, "Its weakness
is that they're slow to change even after you show them." And while a
number of respondents lauded the industry's commitment to research and
development, others claimed it's too esoteric and takes too long to transfer
from the academic level to the factory floor.
Thomas C. Conard, president of Alexander Binzel Corp., had another
take on the industry's weak spots. He noted welding is not a separate industry
in and of itself but instead makes up part of many other industries. The
implication here might be that welding lacks a clear-cut image and direction.
- What business improvements during the next ten years would be in
your company's best interests?
As might be expected, there were nearly as many different answers to
this question as there were respondents. These ranged from broad-based
desires, such as a wish for growth in any field that uses metallic materials, to
a more narrow focus, such as wanting increased use of electronic commerce
and supply chain management. Better trained workers, improved
communication techniques, designing for manufacturability and lessening the
time it takes to get new products to market were all mentioned as in
companies' best interests. Several persons called for increased automation.
Several respondents said a change in the government's role with regard
to their operations would improve their businesses. This could occur either
through less government involvement or through such things as restriction of
imports, "reasonable environmental legislation that does not drive up the cost
of doing business," tort reform in product liability and lower taxes.
133
"We spend a tremendous percentage of our income toward research and
development," explained Emmerson of Magnatech. "The continuation of tax
credits for small company R&D would be beneficial. We note that several of
the Canadian provinces are very aggressive in nurturing technical innovation
and the growth of small companies, and allow virtually all R&D expenditures
to be written off against income. I believe there would be an explosion of
new development and company growth if any of the state governments
undertook similar tax credit programs."
- What has to be done in the future to keep the welding industry healthy?
More than 50% of the respondents believe improving the image of
welding so top students will be drawn to the industry and bettering training
methods for welders and welding engineers are the keys to welding's future.
We need to "totally revise the public education system in the United
States to acknowledge the trades as an acceptable alternative for students,"
according to Connell of Detroit Edison. This echoed the opinion of David
Yapp, team leader, arc welding and automation, Edison Welding Institute,
who said there needs to be "a radical change in education at all levels." He
added, however, "This is not likely to happen without strong leadership and
commitment."
In fact, respondents touched on a variety of aspects related to training all with an eye toward welding's future. In the opinion of Jackie Morris,
quality manager at Bender Shipbuilding & Repair Co., Inc., the level of
cooperation between manufacturers and schools must improve so that
manufacturers' needs are met. Genesis' O'Connell said the welding industry
needs to do two things: "Enhance ease of use through technical training and
technology advancement," and "concentrate on making welding the low cost,
best performance choice for material joining." For the question regarding
welding's weaknesses, Anderson stated it's "often not scientifically applied,
which leads to overdesigned weldments and process parameters that are not
optimized." Anderson touched on the topic again in answer to the above
question, when he said, we must "continue to educate students on the basics
of the process and how to implement it. (We must) teach the economics of
welding to designers so they understand the costs of a weld."
Respondents also mentioned improved salaries for welders, staying
ahead of environmental and health issues and more practical research and
development as ways the welding industry can help itself stay healthy.
- Are you optimistic or pessimistic about the future of your particular
industry?
134
Overwhelmingly, the respondents to the survey said they were
optimistic about the future of their industries. In fact, 92% of respondents
indicated they are at least guardedly optimistic about the future. One
respondent summed up his reasons this way: "Metallics will be around for a
long time and they will need to be joined."
Much the same opinion was held by Lincoln's Sumner. "I am
optimistic," he said. "Even though we are mainly tied to the steel industry,
which has seen a slight decline, we have much more to learn about welding
and furthering the process of joining metals. I believe products and services
that the welding industry provides will continue to be in demand worldwide."
Paul D. Cunningham, president of Weldsale, indicated he was
optimistic because "gains in technology via software and the Internet will
help increase productivity in the U.S.A." Winslow of Hypertherm foresees a
bright future: "If we improve our understanding of our worldwide customers'
needs, we have a road map to unrestricted growth."
However, some respondents, such as Thomas A. Ferri, a welding
process specialist with Airgas, expressed optimism while adding a word of
caution. Ferri said he was "optimistic so long as we know our industry needs
some changes." Morris of Bender said he was "optimistic in that shipbuilding
and repair is a sound profession with an increasing market; pessimistic in that
environmental restraints are greatly increasing operating costs and decreasing
profit margins. There is a need for better dialog between industry and the
private sector."
- During the 1990s, the trend has been for company buyouts and
mergers. Do you see that trend continuing and is it healthy for your
industry?
Not all of the respondents answered both parts of the above question.
From the answers received, three times as many respondents believed the
trend for company buyouts and mergers will continue. Several stated,
however, that the pace will slow from that of the early 1990s. Besides
slowing down, "a certain degree of counteraction, i.e., divestitures, may also
begin to take place," according to Plotica. "For the most part, the buyouts and
mergers have been healthy by providing resources and growth opportunities
to small- to medium-sized companies that would have not been possible
otherwise." With regard to it being a positive trend, most respondents agreed
with Plotica. In fact, three times as many respondents stated it is a healthy
trend as opposed to those who believe it is not good for industry. "Every
buyout and merger has victims and winners," one respondent said. "It also
creates opportunities. Ultimately the industry does become more efficient,
which is healthy."
135
It appeared, however, that respondents who work for welding
equipment and consumables manufacturers rather than end users were more
likely to consider it a negative trend. "The welding industry is getting smaller
every year," one respondent wrote. Another said, "Who's left to buy without
creating an antitrust monopoly issue?"
Langdon of Vermeer presented a case for both sides. On the positive
side, Langdon said, "Larger companies have more resources for research and
development. Also, mergers present a larger buying power and, in some
cases, allegiances to manufacturers. Some of the buyouts that we are seeing,
especially in the equipment rental industry, could be a real boon to our
company." On the negative side, "less competition," he said.
While stating that "company buyouts and mergers can have very
positive benefits for the industry and the consumer," Emmerson also put in a
word of caution. "To use an overworked phrase," he said, "if there are no
'synergies' between a group of companies beyond the fact that they are
associated with the welding industry, the risk is that the performance of
small, newly acquired companies will suffer as their original owners bail out
and no strong management fills the void."
Sumner voiced the opinion of several respondents when he said, "I
believe that these consolidations have fostered an environment that is healthy
for the industry with more focused competition between larger
manufacturers. This competition is good for all of us to help move the
industry forward and provide customer solutions."
Conclusion
Since time machines still exist only in the stories of H. G. Wells and
other works of science fiction, no one can tell us exactly how welding will
fare in the 21st century. However, the people who responded to the Welding
Journal survey represent a cross section of fabricators of welded products and
producers of welding equipment and related products. Together they offer a
wide range of experience and knowledge. Answering the questions
separately, in their respective cities, they still formed a consensus. They agree
the future looks promising for welding. It remains and will continue to be a
productive, cost-effective manufacturing method. However, steps must be
taken to bring more skilled personnel into the industry, or changes must be
made to accommodate for the lack of skilled personnel (e.g., welding
automation). They also indicated the welding industry must embrace all of
the modern-day technological tools to keep pace with the rest of the world.
136
After reading activity
Continue the list of optimistic and pessimistic scenarios for welding
technology development in the future.
“projections for the future are
generally optimistic…”
1. Welding is here to stay and will be
used more in the future.
2. The consumer welding market will
continue to provide opportunities for
growth.
3. …
“but a few gray clouds roam the
horizon”
1. Designs will be more efficient to
minimize the amount of welding.
2. There will be a decline in the use
of gas metal arc (GMAW) and gas
tungsten arc welding (GTAW).
3. …
Translate the following sentences into Russian:
1. Производители сварочного оборудования, приспособлений и
присадочного материала уверены, что их рынок сбыта будет в
дальнейшем расширяться.
2. Технологии получения механических соединений будут вытесняться
в промышленности полу- и автоматическими технологиями соединений,
что приведет к дальнейшему развитию сварки.
3. Для сварки новых металлов потребуется большая точность.
4. Даже на малых предприятиях могут появиться роботы и
оборудование с числовым программным управлением.
5. Для успешного развития сварочных технологий необходимо
привлекать высококвалифицированный персонал.
6. Стремление к увеличению производительности и сокращению
расходов делает необходимым дальнейшую автоматизацию сварочного
производства.
7. Поглощение и слияние компаний, занятых в сфере производства
сварочного оборудования и расходных материалов, будет в ближайшее
время продолжаться.
8. Научные исследования и опытно-конструкторские разработки
положительно сказываются на качестве сварочного оборудования и
расходных материалах.
9. Сварка в настоящее время остается одним из эффективных и
рентабельных технологических процессов.
137
PART 7. HEALTH, SAFETY AND ACCIDENT PREVENTION
In this part guidelines are given on the principal health and safety
considerations to ensure safe welding practices and prevent accidents. Health
risks associated with fume and gases generated during welding are
highlighted.
Pre reading activity
Think and say:
1. Do you think welding is a dangerous/hazardous profession?
2. What type/types of welding do you consider the most/least hazardous?
Why?
Vocabulary
irritation
respiratory tract
susceptibility
fever
tickling
chest tightness
flu
coughing
limb
siderosis
pneumonia
pulmonary
oedema
asphyxiation
exposure
cancer
раздражение
дыхательные пути
чувствительность; восприимчивость
жар, лихорадка; какое-л. заболевание, основным
симптомом которого является очень высокая
температура
першение (в горле)
стесненное дыхание
грипп
кашель
конечность (человека или животного)
сидероз
воспаление легких, пневмония
отек легких
удушье
подвергание какому-л. воздействию; выставление,
оставление на солнце, под дождем и т. п.
рак
138
Reading
Text 1. Health Risks of Welding Fume/Gases
What is welding fume/gases?
Welding fume is a mixture of airborne fine particles.
Toxic gases may also be generated during welding and
cutting.
Particulate fume
More than 90% of the particulate fume arises from
vaporisation of the consumable electrode, wire or rod as
material is transferred across the arc or flame. The range of
welding particles size is shown in relation to the more familiar types of dust
and fume. The respirable fraction of particles (especially less than 3µm) are
potentially the more harmful as they can penetrate to the innermost parts of
the lung.
Gases
Gases encountered in welding may be:
- Fuel gases which, on combustion, form carbon dioxide and, if the flame is
reducing, carbon monoxide;
- Shielding gases such as argon, helium and carbon dioxide, either alone or in
mixtures with oxygen or hydrogen;
- Carbon dioxide and monoxide produced by the action of heat on the
welding flux or slag;
- Nitric oxide, nitrogen dioxide and ozone produced by the action of heat or
ultraviolet radiation on the atmosphere surrounding the welding arc;
- Gases from the degradation of solvent vapours or surface contaminants on
the metal.
The degree of risk to the welder's health from fume/gases will depend on
composition, concentration, the length of time the welder is exposed, the
welder's susceptibility.
Health hazards from particulate fume
The potential hazards from breathing in particulate fume are:
1. Irritation of the respiratory tract. Fine
particles can cause dryness of the throat, tickling,
coughing and if the concentration is particularly high,
tightness of the chest and difficulty in breathing.
2. Metal fume fever. Breathing in metal oxides
such as zinc and copper can lead to an acute flu-like
illness called 'metal fume fever'. It most commonly
occurs when welding galvanised steel; symptoms usually begin several hours
139
after exposure with a thirst, cough, headache, sweat, pain in the limbs and
fever. Complete recovery usually occurs within 1 to 2 days of removal from
the exposure, without any lasting effects.
3. Longer term effects. The continued inhalation of welding fume
over long periods of time can lead to the deposition of iron particles in the
lung, giving rise to a benign condition called siderosis. There is evidence that
welders have a slightly greater risk of developing lung cancer than the
general population. In certain welding situations, there is potential for the
fume to contain certain forms of chromium and/or nickel compounds substances which have been associated with lung cancer in processes other
than welding. As yet, no direct link has been clearly established.
Nevertheless, as a sensible precaution and to minimise the risk, special
attention should be paid to controlling fumes which may contain them.
Additional hazards
A number of other specific substances known to be hazardous to health
can be found in welding fume such as barium and fluorides which do not
originate from the metal. If the metal contains a surface coating, there will
also be a potential risk from any toxic substances generated by thermal
degradation of the coating.
Health hazards from gases
The potential hazards from breathing in gases during welding are:
1. Irritation of the respiratory tract. Ozone can cause delayed
irritation of the respiratory tract which may progress to bronchitis and
occasionally pneumonia. Nitrogen oxides can cause a dry irritating cough and
chest tightness. Symptoms usually occur after a delay of 4 to 8 hours. In
severe cases, death can occur from pulmonary oedema (fluid on the lungs)
or pneumonia.
2. Asphyxiation. There may be a risk of asphyxiation due to
replacement of air with gases produced when welding in a workshop or area
with inadequate ventilation. Special precautions are needed when welding in
confined spaces where there is the risk of the build up of inert shielding
gases. Carbon monoxide, formed as a result of incomplete combustion of fuel
gases, can also cause asphyxiation by replacing the oxygen in the blood.
Establishing safe levels of fume in the workplace
The COSHH Regulations* require that exposure is controlled below
specific limits. The limits, known as occupational exposure limits, are
detailed in EH 40 which is revised periodically. The majority of limits listed
are for single substances. Only a few relate to substances which are complex
140
mixtures; welding fume is one of these. It has an occupational exposure limit
but account must also be taken of the exposure limits of the individual
constituents. So, in considering what would be safe exposure levels to
welding fume, not only should exposure be controlled to within the welding
fume limit but also the individual components must be controlled to within
their own limits. The assessment of exposure to fume from welding processes
is covered in EH 54.
Substances may have a maximum exposure limit (MEL) or an
occupation exposure standard (OES).
A MEL is the maximum concentration of an airborne substance to
which people may be exposed under any circumstances. Exposure must be
reduced as far as is reasonably practicable and at least below any MEL.
An OES is the concentration of an airborne substance, for which (according
to current information) there is no evidence that it is likely to cause harm to a
person's health , even if they are exposed day after day. Control is thought to
be adequate if exposure is reduced to or below the standard.
The OESs and the MELs of some of the substances found in welding
fume are listed in Table below; the absence of other substances from this list
does not indicate that they are safe.
Table. Occupational Exposure Limits
8hr TWA
Substances Assigned a Maximum Exposure
Limit
Beryllium
0.002
mg/m 3
Cadmium oxide fume (as Cd)
0.025
mg/m 3
0.05 mg/m
Chromium VI compounds (as Cr)
3
Cobalt
0.1 mg/m 3
Nickel (insoluble compounds)
0.5 mg/m 3
Substances Assigned an Occupational
Exposure Standard
141
15 min
STEL
Welding fume
5 mg/m 3
Fluoride (as F)
2.5 mg/m 3
Iron oxide, fume (as Fe)
5 mg/m 3
10 mg/m 3
Zinc oxide, fume
5 mg/m 3
10 mg/m 3
Manganese, fume (as Mn)
0.5 mg/m 3
Ozone
0.2 ppm
Nitric Oxide
1 ppm
Nitrogen dioxide
1 ppm
Chromium III compounds (as Cr)
0.5 mg/m 3
Barium compounds, soluble (as Ba)
0.5 mg/m 3
Carbon monoxide
50 ppm
Copper fume
0.2 mg/m 3
300 ppm
If the fume contains only substances such as iron or aluminium which
are of low toxicity, an 8 hour (TWA) OES of 5mg/m3 applies; this figure is
the average concentration of particulate fume that should not be exceeded in
an 8 hour day.
* Control of Substances Hazadous to Health (COSHH) Regulations.
The Control of Substances Hazardous to Health (COSSH) Regulations 2002
require employers to monitor the safe use of chemicals and hazardous
substances at work. It requires them to: control exposure to hazardous
substances to prevent ill health both now and any future cumulative effects
they may have, protect both employees and others who might be exposed,
compile records of employees using these materials, supply employees with
suitable personal protective equipment.
After reading activity
Think of Russian equivalents for the following word combinations from the
text:
Innermost parts of the lung, fuel gas, fine particles, respirable fraction
of particles, carbon dioxide, ultraviolet radiation, galvanised steel, lasting
effects, welding situations, lung cancer, sensible precaution, surface coating,
general population, inadequate ventilation, risk of the build up of inert
142
shielding gases, incomplete combustion, occupational exposure limit, to
cause harm to a person's health.
Speaking
True or false?
1. The smaller the particles the more harmful the fume is.
2. The risk to the welder's health from fume or gases depends on the welding
arc.
3. Welders have lung cancer more often than the general population.
4. Asphyxiation may happen due to inadequate ventilation.
5. Metal fume fever is an incurable illness.
Fill in the gaps in the following sentences or complete them:
1. Argon is a … gas.
2. Particulate fume is very … for man’s health.
3. When exposed to particulate fume of high concentration for a long time, a
welder may … .
4. Welding galvanised steel may cause … .
5. Asphyxiation may happen due to … .
6. To minimise the risk, special attention should be paid to controlling fumes
which may contain chromium or … compounds.
7. In case of metal fume fever, …. recovery occurs soon after removal of the
welder from the exposure.
8. … is a disease caused by fluid on the lungs.
9. MEL means maximum … limit.
10. OES is … exposure standard.
11. Gases encountered in welding are … .
Answer the following questions:
1. What is the difference between welding fume and welding gas?
2. What does the major part of the particulate fume arise from?
3. What does the degree of risk to the welder's health from fume or gases
depend on?
4. Under what condition is control over the exposure of welders to hazardous
fumes or gases considered adequate?
5. Do the COSHH Regulations state only single substances?
143
Vocabulary
bare spot
wire feeder
ground
connection
power
switch
rupture
confined
space
exhaust
hood
оголенный участок
механизм подачи (электродной или присадочной)
проволоки
1) заземление, замыкание на землю 2) соединение на
корпус
переключатель мощности
а) пробой (изоляции) б) излом, разрушение, разрыв
замкнутый объём, замкнутое пространство
вытяжной шкаф; вытяжной колпак
Reading
Text 2. Safety and Scheduled Maintenance Protect Your Welding Assets
Q: What can I do to avoid electrical shocks?
A: Wet working conditions must be avoided, because water is an excellent
conductor and electricity will always follow the path of least resistance. Even
a person's perspiration can lower the body's resistance to electrical shock.
Poor connections and bare spots on cables further increase the possibility of
electrical shock, and therefore, daily inspection of these items is
recommended. Equipment operators should also routinely inspect for proper
ground connections.
Q: How can I inspect and maintain my wire feeder?
A: Periodically inspect the electrode wire drive rolls. If dirty, remove the
drive rolls and clean with a wire brush. Deformed drive rolls should be
replaced. Drive rolls should be changed, adjusted or cleaned only when the
wire feeder is shut off. In addition, check the inlet and outlet guides and
replace if they are deformed from wire wear. Remember that when power is
applied to a wire feeder, fingers should be kept away from the drive roll area.
Q: What are some important electrode safety considerations?
A: Welding power sources for use with MIG and TIG welding normally are
equipped with devices that permit on/off control of the welding power output.
If so, the electrode becomes electrically hot when the power source switch is
ON and the welding gun switch is closed. Never touch the electrode wire or
any conducting object in contact with the electrode circuit, unless the welding
power source is off. Welding power sources used for shielded metal arc
welding (SMAW or Stick welding) may not be equipped with welding power
144
output on/off control devices. With such equipment, the electrode is
electrically hot when the power switch is turned ON.
Q: How should I store my gas cylinders?
A: Cylinders should be securely fastened at all times. Chains are usually used
to secure a cylinder to a wall or cylinder cart. When moving or storing a
cylinder, a threaded protector cap must be fastened to the top of the cylinder.
This protects the valve system should it be bumped or dropped. Cylinders
should not be stored or used in a horizontal position. This is because some
cylinders contain a liquid which would leak out or be forced out if the
cylinder was laid in a flat position. Also, welding guns and other cables
should not be hung on or near cylinders. A gun could cause an arc against the
cylinder wall or valve assembly, possibly resulting in a weakened cylinder or
even a rupture.
Q: How can I tell if my regulator is faulty?
A: The following symptoms indicate a faulty regulator:
Leaks - if gas leaks externally.
Excessive сreep - if delivery pressure continues to rise with the downstream
valve closed.
Faulty gauge - if gauge pointer does not move off the stop pin when
pressurized, nor returns to the stop pin after pressure release. Do not attempt
to repair a faulty regulator. It should be sent to your designated repair center,
where special techniques and tools are used by trained personnel.
Q: What are some tips for a safe welding environment?
A: The area surrounding the welder will be subjected to light, heat, smoke,
sparks and fumes. Permanent booths or portable partitions can be used to
contain light rays in one area. The heat and sparks given off are capable of
setting flammable materials on fire. Therefore, welding should not be done in
areas containing flammable gases, vapors, liquids or dusty locations where
explosions are a possibility. Metals with plating, coatings or paint that come
near the region of the arc may give off smoke and fumes during welding.
These fumes may pose a health hazard to the lungs, therefore an exhaust
hood or booth should be used to remove fumes from the area. When welding
in confined spaces, such as inside tanks, large containers or even
compartments of a ship, toxic fumes may gather. Also, in an enclosed room,
breathable oxygen can be replaced by shielding gases used for welding or
purging. Care must be taken to ensure enough clean air for breathing. In
many companies, it is routine to provide welders with air masks or selfcontained breathing equipment.
Q: How should an operator dress for optimum safety?
A: Gloves and clothing should be flame-resistant. Clothing made from a
dark-colored, tightly woven material is best suited for welding. Gauntlet-type
145
leather gloves should be worn to protect the hands and wrists. Shirt collars
and shirt cuffs should be buttoned, and open front pockets are not advisable
as they may catch sparks. Also, operators should never store matches or
lighters in their pockets. Pants cuffs are not recommended, as they will also
catch sparks. Tennis shoes do not qualify as adequate foot protection. Hightop leather shoes or boots are absolutely necessary.
Q: Is there a daily maintenance schedule I should follow?
A: Below is a general engine drive routine daily maintenance schedule, but it
should be modified according to a company's specific conditions. By
following a regimen of appropriate and thorough maintenance and safety, a
welder from Miller Electric can run dependably for decades. Designed to
withstand rough use, these machines use high quality components and are
tested for durability.
After reading activity
Find the Russian equivalents for the following English word combinations:
electrical shock, daily inspection, wire brush, power sources, flammable
gases, cylinder cart, toxic fumes, open front pockets, toxic substances, flat
position, airborne substance, trained personnel, air mask, flame-resistant.
Find the English equivalents in the text for the following word combinations:
путь наименьшего сопротивления, поражение электрическим током,
соображения безопасности, защитный колпак, обученный персонал,
наносить вред, грубое обращение.
Speaking
Answer each of the above questions in just one sentence:
Model: Q: What can I do to avoid electrical shocks?
A: To avoid electrical shocks you should not operate in wet working
conditions check your circuit for poor connections and bare spots.
Look at a Maintenance Schedule Chart below and say what a welder should
do in terms of maintenance:
- once a working day;
- once a week;
- once a month.
146
Maintenance Schedule Chart
8 Hours
50 Hours
100
Hours
200
Hours
250
Hours
500
Hours
1000
Hours
Wipe up oil and fuel spills immediately
Check fluid levels (oil & fuel)
Service the air filter (refer to engine manual for specifics)
Service air filter element (refer to engine manual for specifics)
Clean and tighten weld terminals
Change oil
Change oil filter (refer to engine manual for specifics)
Clean and tighten battery connections
Clean cooling system (refer to engine manual for specifics)
Replace unreadable labels (order from parts list)
Replace fuel filter
Check valve clearance (refer to engine manual for specifics)
Check and clean spark arrestor
Tape or replace cracked cables
Clean/Set injectors (refer to engine manual for specifics)
Blow out or vacuum inside equipment. During heavy service, do
this monthly.
Answer the following questions:
1. What should be inspected daily by a welding operator to avoid electric
shock?
2. What should be cleaned/ changed/ replaced while maintaining wire feeder?
3. Why shouldn’t you touch the electrode wire when the welding power
source is on?
4. Why shouldn’t cylinders be stored or used in a horizontal position?
5. Should you try to repair a faulty regulator yourself?
6. What are booths and partitions used for?
7. What shouldn’t a welder store in his pockets?
Writing
Summarize the information of the text using the following incomplete
sentences as a plan:
1. To avoid electrical shocks a welder should/shouldn’t… (inspect, repair,
etc.)
147
2. The following things should be remembered when inspecting and
maintaining wire feeder … .
3. To use and store electrodes safely, one should/shouldn’t … .
4. Gas cylinders should be stored in the following way: … .
5. If the regulator is faulty, you can observe the following: … .
6. Safe welding environment is obtained by … .
7. Welding operators should be dressed in … .
8. To keep welding equipment running for decades, operator should do some
operations on a regular basis, such as … .
APPENDIX 1. WELDING THEORY & APPLICATION DEFINITIONS
ACETONE:
A flammable, volatile liquid used in acetylene cylinders to dissolve
and stabilize acetylene under high pressure.
ACETYLENE:
A highly combustible gas composed of carbon and hydrogen. Used as
a fuel gas in the oxyacetylene welding process.
ACTUAL THROAT:
See THROAT OF FILLET WELD.
AIR-ACETYLENE:
A low temperature flare produced by burning acetylene with air instead
of oxygen.
AIR-ARC CUTTING:
An arc cutting process in which metals to be cut are melted by the heat
of the carbon arc.
ALLOY:
A mixture with metallic properties composed of two or more elements,
of which at least one is a metal.
ALTERNATING CURRENT:
An electric current that reverses its direction at regularly recurring
intervals.
AMMETER:
An instrument for measuring electrical current in amperes by an
indicator activated by the movement of a coil in a magnetic field or by
the longitudinal expansion of a wire carrying the current.
ANNEALING:
A comprehensive term used to describe the heating and cooling cycle
of steel in the solid state. The term annealing usually implies relatively
slow cooling. In annealing, the temperature of the operation, the rate of
148
heating and cooling, and the time the metal is held at heat depend upon
the composition, shape, and size of the steel product being treated, and
the purpose of the treatment. The more important purposes for which
steel is annealed are as follows: to remove stresses; to induce softness;
to alter ductility, toughness, electric, magnetic, or other physical and
mechanical properties; to change the crystalline structure; to remove
gases; and to produce a definite microstructure.
ARC BLOW:
The deflection of an electric arc from its normal path because of
magnetic forces.
ARC BRAZING:
A brazing process wherein the heat is obtained from an electric arc
formed between the base metal and an electrode, or between two
electrodes.
ARC CUTTING:
A group of cutting processes in which the cutting of metals is
accomplished by melting with the heat of an arc between the electrode
and the base metal. See CARBON-ARC CUTTING, METAL-ARC
CUTTING, ARC-OXYGEN CUTTING, AND AIR-ARC CUTTING.
ARC LENGTH:
The distance between the tip of the electrode and the weld puddle.
ARC-OXYGEN CUTTING:
An oxygen-cutting process used to sever metals by a chemical reaction
of oxygen with a base metal at elevated temperatures.
ARC VOLTAGE:
The voltage across the welding arc.
ARC WELDING:
A group of welding processes in which fusion is obtained by heating
with an electric arc or arcs, with or without the use of filler metal.
AS WELDED:
The condition of weld metal, welded joints, and weldments after
welding and prior to any subsequent thermal, mechanical, or chemical
treatments.
ATOMIC HYDROGEN WELDING:
An arc welding process in which fusion is obtained by heating with an
arc maintained between two metal electrodes in an atmosphere of
hydrogen. Pressure and/or filler metal may or may not be used.
AUSTENITE:
The non-magnetic form of iron characterized by a face-centered cubic
lattice crystal structure. It is produced by heating steel above the upper
149
critical temperature and has a high solid solubility for carbon and
alloying elements.
AXIS OF A WELD:
A line through the length of a weld, perpendicular to a cross section at
its center of gravity.
BACK FIRE:
The momentary burning back of a flame into the tip, followed by a
snap or pop, then immediate reappearance or burning out of the flame.
BACK PASS:
A pass made to deposit a back weld.
BACK UP:
In flash and upset welding, a locator used to transmit all or a portion of
the upsetting force to the workpieces.
BACK WELD:
A weld deposited at the back of a single groove weld.
BACKHAND WELDING:
A welding technique in which the flame is directed towards the
completed weld.
BACKING STRIP:
A piece of material used to retain molten metal at the root of the weld
and/or increase the thermal capacity of the joint so as to prevent
excessive warping of the base metal.
BACKING WELD:
A weld bead applied to the root of a single groove joint to assure
complete root penetration.
BACKSTEP:
A sequence in which weld bead increments are deposited in a direction
opposite to the direction of progress.
BARE ELECTRODE:
An arc welding electrode that has no coating other than that incidental
to the drawing of the wire.
BARE METAL-ARC WELDING:
An arc welding process in which fusion is obtained by heating with an
unshielded arc between a bare or lightly coated electrode and the work.
Pressure is not used and filler metal is obtained from the electrode.
BASE METAL:
The metal to be welded or cut. In alloys, it is the metal present in the
largest proportion.
BEAD WELD:
A type of weld composed of one or more string or weave beads
deposited on an unbroken surface.
150
BEADING:
See STRING BEAD WELDING and WEAVE BEAD.
BEVEL ANGLE:
The angle formed between the prepared edge of a member and a plane
perpendicular to the surface of the member.
BLACKSMITH WELDING:
See FORGE WELDING.
BLOCK BRAZING:
A brazing process in which bonding is produced by the heat obtained
from heated blocks applied to the parts to be joined and by a
nonferrous filler metal having a melting point above 800 °F (427 °C),
but below that of the base metal. The filler metal is distributed in the
joint by capillary attraction.
BLOCK SEQUENCE:
A building up sequence of continuous multipass welds in which
separated lengths of the weld are completely or partially built up
before intervening lengths are deposited. See BUILDUP SEQUENCE.
BLOW HOLE:
see GAS POCKET.
BOND:
The junction of the welding metal and the base metal.
BOXING:
The operation of continuing a fillet weld around a corner of a member
as an extension of the principal weld.
BRAZING:
A group of welding processes in which a groove, fillet, lap, or flange
joint is bonded by using a nonferrous filler metal having a melting
point above 800 °F (427 °C), but below that of the base metals. Filler
metal is distributed in the joint by capillary attraction.
BRAZE WELDING:
A method of welding by using a filler metal that liquefies above 450
°C (842 °F) and below the solid state of the base metals. Unlike
brazing, in braze welding, the filler metal is not distributed in the joint
by capillary action.
BRIDGING:
A welding defect caused by poor penetration. A void at the root of the
weld is spanned by weld metal.
BUCKLING:
Distortion caused by the heat of a welding process.
BUILDUP SEQUENCE:
151
The order in which the weld beads of a multipass weld are deposited
with respect to the cross section of a joint. See BLOCK SEQUENCE.
BUTT JOINT:
A joint between two workpieces in such a manner that the weld joining
the parts is between the surface planes of both of the pieces joined.
BUTT WELD:
A weld in a butt joint.
BUTTER WELD:
A weld caused of one or more string or weave beads laid down on an
unbroken surface to obtain desired properties or dimensions.
CAPILLARY ATTRACTION:
The phenomenon by which adhesion between the molten filler metal
and the base metals, together with surface tension of the molten filler
metal, causes distribution of the filler metal between the properly fitted
surfaces of the joint to be brazed.
CARBIDE PRECIPITATION:
A condition occurring in austenitic stainless steel which contains
carbon in a supersaturated solid solution. This condition is unstable.
Agitation of the steel during welding causes the excess carbon in
solution to precipitate. This effect is also called weld decay.
CARBON-ARC CUTTING:
A process of cutting metals with the heat of an arc between a carbon
electrode and the work.
CARBON-ARC WELDING:
A welding process in which fusion is produced by an arc between a
carbon electrode and the work. Pressure and/or filler metal and/or
shielding may or may not be used.
CARBONIZING FLAME:
An oxyacetylene flame in which there is an excess of acetylene. Also
called excess acetylene or reducing flame.
CASCADE SEQUENCE: Subsequent beads are stopped short of a previous
bead, giving a cascade effect.
CASE HARDENING:
A process of surface hardening involving a change in the composition
of the outer layer of an iron base alloy by inward diffusion from a gas
or liquid, followed by appropriate thermal treatment. Typical
hardening processes are carbonizing, cyaniding, carbonitriding, and
nitriding.
CHAIN INTERMITTENT FILLET WELDS:
Two lines of intermittent fillet welds in a T or lap joint in which the
welds in one line are approximately opposite those in the other line.
152
CHAMFERING:
The preparation of a welding contour, other than for a square groove
weld, on the edge of a joint member.
COALESCENCE:
The uniting or fusing of metals upon heating.
COATED ELECTRODE:
An electrode having a flux applied externally by dipping, spraying,
painting, or other similar methods. Upon burning, the coat produces a
gas which envelopes the arc.
COMMUTORY CONTROLLED WELDING:
The making of a number of spot or projection welds in which several
electrodes, in simultaneous contact with the work, progressively
function under the control of an electrical commutating device.
COMPOSITE ELECTRODE:
A filler metal electrode used in arc welding, consisting of more than
one metal component combined mechanically. It may or may not
include materials that improve the properties of the weld, or stabilize
the arc.
COMPOSITE JOINT:
A joint in which both a thermal and mechanical process are used to
unite the base metal parts.
CONCAVITY:
The maximum perpendicular distance from the face of a concave weld
to a line joining the toes.
CONCURRENT HEATING:
Supplemental heat applied to a structure during the course of welding.
CONE:
The conical part of a gas flame next to the orifice of the tip.
CONSUMABLE INSERT:
Preplaced filler metal which is completely fused into the root of the
joint and becomes part of the weld.
CONVEXITY:
The maximum perpendicular distance from the face of a convex fillet
weld to a line joining the toes.
CORNER JOINT:
A joint between two members located approximately at right angles to
each other in the form of an L.
COVER GLASS:
A clear glass used in goggles, hand shields, and helmets to protect the
filter glass from spattering material.
COVERED ELECTRODE:
153
A metal electrode with a covering material which stabilizes the arc and
improves the properties of the welding metal. The material may be an
external wrapping of paper, asbestos, and other materials or a flux
covering.
CRACK:
A fracture type discontinuity characterized by a sharp tip and high ratio
of length and width to opening displacement.
CRATER:
A depression at the termination of an arc weld.
CRITICAL TEMPERATURE:
The transition temperature of a substance from one crystalline form to
another.
CURRENT DENSITY:
Amperes per square inch of the electrode cross sectional area.
CUTTING TIP:
A gas torch tip especially adapted for cutting.
CUTTING TORCH:
A device used in gas cutting for controlling the gases used for
preheating and the oxygen used for cutting the metal.
CYLINDER:
A portable cylindrical container used for the storage of a compressed
gas.
DEFECT:
A discontinuity or discontinuities which, by nature or accumulated
effect (for example, total crack length), render a part or product unable
to meet the minimum applicable acceptance standards or
specifications. This term designates rejectability.
DEPOSITED METAL:
Filler metal that has been added during a welding operation.
DEPOSITION EFFICIENCY:
The ratio of the weight of deposited metal to the net weight of
electrodes consumed, exclusive of stubs.
DEPTH OF FUSION:
The distance from the original surface of the base metal to that point at
which fusion ceases in a welding operation.
DIE:
a. Resistance Welding. A member, usually shaped to the work contour,
used to clamp the parts being welded and conduct the welding current.
b. Forge Welding. A device used in forge welding primarily to form
the work while hot and apply the necessary pressure.
DIE WELDING:
154
A forge welding process in which fusion is produced by heating in a
furnace and by applying pressure by means of dies.
DIP BRAZING:
A brazing process in which bonding is produced by heating in a molten
chemical or metal bath and by using a nonferrous filler metal having a
melting point above 800 °F (427 °C), but below that of the base metals.
The filler metal is distributed in the joint by capillary attraction. When
a metal bath is used, the bath provides the filler metal.
DIRECT CURRENT ELECTRODE NEGATIVE (DCEN):
The arrangement of direct current arc welding leads in which the work
is the positive pole and the electrode is the negative pole of the
welding arc.
DIRECT CURRENT ELECTRODE POSITIVE (DCEP):
The arrangement of direct current arc welding leads in which the work
is the negative pole and the electrode is the positive pole of the
welding arc.
DISCONTINUITY:
An interruption of the typical structure of a weldment, such as lack of
homogeneity in the mechanical, metallurgical, or physical
characteristics of the material or weldment. A discontinuity is not
necessarily a defect.
DRAG:
The horizontal distance between the point of entrance and the point of
exit of a cutting oxygen stream.
DUCTILITY:
The property of a metal which allows it to be permanently deformed,
in tension, before final rupture. Ductility is commonly evaluated by
tensile testing in which the amount of elongation and the reduction of
area of the broken specimen, as compared to the original test specimen,
are measured and calculated.
DUTY CYCLE:
The percentage of time during an arbitrary test period, usually 10
minutes, during which a power supply can be operated at its rated
output without overloading.
EDGE JOINT:
A joint between the edges of two or more parallel or nearly parallel
members.
EDGE PREPARATION:
The contour prepared on the edge of a joint member for welding.
EFFECTIVE LENGTH OF WELD:
155
The length of weld throughout which the correctly proportioned cross
section exits.
ELECTRODE:
a. Metal-Arc. Filler metal in the form of a wire or rod, whether bare or
covered, through which current is conducted between the electrode
holder and the arc.
b. Carbon-Arc. A carbon or graphite rod through which current is
conducted between the electrode holder and the arc.
c.Atomic . One of the two tungsten rods between the points of which
the arc is maintained.
d. Electrolytic Oxygen-Hydrogen Generation. The conductors by
which current enters and leaves the water, which is decomposed by the
passage of the current.
e. Resistance Welding. The part or parts of a resistance welding
machine through which the welding current and the pressure are
applied directly to the work.
ELECTRODE FORCE:
a. Dynamic. In spot, seam, and projection welding, the force (pounds)
between the electrodes during the actual welding cycle.
b. Theoretical. In spot, seam, and projection welding, the force,
neglecting friction and inertia, available at the electrodes of a
resistance welding machine by virtue of the initial force application
and the theoretical mechanical advantage of the system.
c. Static. In spot, seam, and projection welding, the force between the
electrodes under welding conditions, but with no current flowing and
no movement in the welding machine.
ELECTRODE HOLDER:
A device used for mechanically holding the electrode and conduct- ing
current to it.
ELECTRODE SKID:
The sliding of an electrode along the surface of the work during spot,
seam, or projection welding.
EMBOSSMENT:
A rise or protrusion from the surface of a metal.
ETCHING:
A process of preparing metallic specimens and welds for macrographic
or micrographic examination.
FACE REINFORCEMENT:
Reinforcement of weld at the side of the joint from which welding was
done.
FACE OF WELD:
156
The exposed surface of a weld, made by an arc or gas welding process,
on the side from which welding was done.
FAYING SURFACE:
That surface of a member that is in contact with another member to
which it is joined.
FERRITE:
The virtually pure form of iron existing below the lower critical
temperature and characterized by a body-centered cubic lattice crystal
structure. It is magnetic and has very slight solid solubility for carbon.
FILLER METAL:
Metal to be added in making a weld.
FILLET WELD:
A weld of approximately triangular cross section, as used in a lap joint,
joining two surfaces at approximately right angles to each other.
FILTER GLASS:
A colored glass used in goggles, helmets, and shields to exclude
harmful light rays.
FLAME CUTTING:
see OXYGEN CUTTING.
FLAME GOUGING:
See OXYGEN GOUGING.
FLAME HARDENING:
A method for hardening a steel surface by heating with a gas flame
followed by a rapid quench.
FLAME SOFTENING:
A method for softening steel by heating with a gas flame followed by
slow cooling.
FLASH:
Metal and oxide expelled from a joint made by a resistance welding
process.
FLASH WELDING:
A resistance welding process in which fusion is produced,
simultaneously over the entire area of abutting surfaces, by the heat
obtained from resistance to the flow of current between two surfaces
and by the application of pressure after heating is substantially
completed. Flashing is accompanied by expulsion of metal from the
joint.
FLASHBACK:
The burning of gases within the torch or beyond the torch in the hose,
usually with a shrill, hissing sound.
FLAT POSITION:
157
The position in which welding is performed from the upper side of the
joint and the face of the weld is approximately horizontal.
FILM BRAZING:
A process in which bonding is produced by heating with a molten
nonferrous filler metal poured over the joint until the brazing
temperature is attained. The filler metal is distributed in the joint by
capillary attraction. See BRAZING.
FLOW WELDING:
A process in which fusion is produced by heating with molten filler
metal poured over the surfaces to be welded until the welding
temperature is attained and the required filler metal has been added.
The filler metal is not distributed in the joint by capillary attraction.
FLUX:
A cleaning agent used to dissolve oxides, release trapped gases and
slag, and to cleanse metals for welding, soldering, and brazing.
FOREHAND WELDING:
A gas welding technique in which the flare is directed against the base
metal ahead of the completed weld.
FORGE WELDING:
A group of welding processes in which fusion is produced by heating
in a forge or furnace and applying pressure or blows.
FREE BEND TEST:
A method of testing weld specimens without the use of a guide.
FULL FILLET WELD:
A fillet weld whose size is equal to the thickness of the thinner
member joined.
FURNACE BRAZING:
A process in which bonding is produced by the furnace heat and a
nonferrous filler metal having a melting point above 800 °F (427 °C),
but below that of the base metals. The filler metal is distributed in the
joint by capillary attraction.
FUSION:
A thorough and complete mixing between the two edges of the base
metal to be joined or between the base metal and the filler metal added
during welding.
FUSION ZONE (FILLER PENETRATION):
The area of base metal melted as determined on the cross section of a
weld.
GAS CARBON-ARC WELDING:
An arc welding process in which fusion is produced by heating with an
electric arc between a carbon electrode and the work. Shielding is
158
obtained from an inert gas such as helium or argon. Pressure and/or
filler metal may or may not be used.
GAS METAL-ARC (MIG) WELDING (GMAW):
An arc welding process in which fusion is produced by heating with an
electric arc between a metal electrode and the work. Shielding is
obtained from an inert gas such as helium or argon. Pressure and/or
filler metal may or my not be used.
GAS POCKET:
A weld cavity caused by the trapping of gases released by the metal
when cooling.
GAS TUNGSTEN-ARC (TIG) WELDING (GTAW):
An arc welding process in which fusion is produced by heating with an
electric arc between a tungsten electrode and the work while an inert
gas forms around the weld area to prevent oxidation. No flux is used.
GAS WELDING:
A process in which the welding heat is obtained from a gas flame.
GLOBULAR TRANSFER (ARC WELDING):
A type of metal transfer in which molten filler metal is transferred
across the arc in large droplets.
GOGGLES:
A device with colored lenses which protect the eyes from harmful
radiation during welding and cutting operations.
GROOVE:
The opening provided between two members to be joined by a groove
weld.
GROOVE ANGLE:
The total included angle of the groove between parts to be joined by a
groove weld.
GROOVE FACE:
That surface of a member included in the groove.
GROOVE RADIUS:
The radius of a J or U groove.
GROOVE WELD:
A weld made by depositing filler metal in a groove between two
members to be joined.
GROUND CONNECTION:
The connection of the work lead to the work.
GROUND LEAD:
See WORK LEAD.
GUIDED BEND TEST:
159
A bending test in which the test specimen is bent to a definite shape by
means of a jig.
HAMMER WELDING:
A forge welding process.
HAND SHIELD:
A device used in arc welding to protect the face and neck. It is
equipped with a filter glass lens and is designed to be held by hand.
HARD FACING:
A particular form of surfacing in which a coating or cladding is applied
to a surface for the main purpose of reducing wear or loss of material
by abrasion, impact, erosion, galling, and cavitations.
HARD SURFACING:
The application of a hard, wear-resistant alloy to the surface of a softer
metal.
HARDENING:
a. The heating and quenching of certain iron-base alloys from a
temperature above the critical temperature range for the purpose of
producing a hardness superior to that obtained when the alloy is not
quenched. This term is usually restricted to the formation of
martensite.
b. Any process of increasing the hardness of metal by suitable
treatment, usually involving heating and cooling.
HEAT AFFECTED ZONE:
That portion of the base metal whose structure or properties have been
changed by the heat of welding or cutting.
HEAT TIME:
The duration of each current impulse in pulse welding.
HEAT TREATMENT:
An operation or combination of operations involving the heating and
cooling of a metal or an alloy in the solid state for the purpose of
obtaining certain desirable conditions or properties. Heating and
cooling for the sole purpose of mechanical working are excluded from
the meaning of the definition.
HEATING GATE:
The opening in a thermit mold through which the parts to be welded
are preheated.
HELMET:
A device used in arc welding to protect the face and neck. It is
equipped with a filter glass and is designed to be worn on the head.
HOLD TIME:
160
The time that pressure is maintained at the electrodes after the welding
current has stopped.
HORIZONTAL WELD:
A bead or butt welding process with its linear direction horizontal or
inclined at an angle less than 45 degrees to the horizontal, and the parts
welded being vertically or approximately vertically disposed.
HORN:
The electrode holding arm of a resistance spot welding machine.
HORN SPACING:
In a resistance welding machine, the unobstructed work clearance
between horns or platens at right angles to the throat depth. This
distance is measured with the horns parallel and horizontal at the end
of the downstroke.
HOT SHORT:
A condition which occurs when a metal is heated to that point, prior to
melting, where all strength is lost but the shape is still maintained.
HYDROGEN BRAZING:
A method of furnace brazing in a hydrogen atmosphere.
HYDROMATIC WELDING:
See PRESSURE CONTROLLED WELDING.
HYGROSCOPIC:
Readily absorbing and retaining moisture.
IMPACT TEST:
A test in which one or more blows are suddenly applied to a specimen.
The results are usually expressed in terms of energy absorbed or
number of blows of a given intensity required to break the specimen.
IMPREGNATED-TAPE METAL-ARC WELDING
An arc welding process in which fusion is produced by heating with an
electric arc between a metal electrode and the work. Shielding is
obtained from decomposition of impregnated tape wrapped around the
electrode as it is fed to the arc. Pressure is not used, and filler metal is
obtained from the electrode.
INDUCTION BRAZING:
A process in which bonding is produced by the heat obtained from the
resistance of the work to the flow of induced electric current and by
using a nonferrous filler metal having a melting point above 800 °F
(427 °C), but below that of the base metals. The filler metal is
distributed in the joint by capillary attraction.
INDUCTION WELDING:
161
A process in which fusion is produced by heat obtained from resistance
of the work to the flow of induced electric current, with or without the
application of pressure.
INERT GAS:
A gas which does not normally combine chemically with the base
metal or filler metal.
INTERPASS TEMPERATURE:
In a multipass weld, the lowest temperature of the deposited weld meal
before the next pass is started.
JOINT:
The portion of a structure in which separate base metal parts are
joined.
JOINT PENETRATION:
The maximum depth a groove weld extends from its face into a joint,
exclusive of reinforcement.
KERF:
The space from which metal has been removed by a cutting process.
LAP JOINT:
A joint between two overlapping members.
LAYER:
A stratum of weld metal, consisting of one or more weld beads.
LEG OF A FILLET WELD:
The distance from the root of the joint to the toe of the fillet weld.
LIQUIDUS:
The lowest temperature at which a metal or an alloy is completely
liquid.
LOCAL PREHEATING:
Preheating a specific portion of a structure.
LOCAL STRESS RELIEVING:
Stress relieving heat treatment of a specific portion of a structure.
MANIFOLD:
A multiple header for connecting several cylinders to one or more
torch supply lines.
MARTENSITE:
Martensite is a microconstituent or structure in quenched steel
characterized by an acicular or needle-like pattern on the surface of
polish. It has the maximum hardness of any of the structures resulting
from the decomposition products of austenite.
MASH SEAM WELDING:
162
A seam weld made in a lap joint in which the thickness at the lap is
reduced to approximately the thickness of one of the lapped joints by
applying pressure while the metal is in a plastic state.
MELTING POINT:
The temperature at which a metal begins to liquefy.
MELTING RANGE:
The temperature range between solidus and liquidus.
MELTING RATE:
The weight or length of electrode melted in a unit of time.
METAL-ARC CUTTING:
The process of cutting metals by melting with the heat of the metal arc.
METAL-ARC WELDING:
An arc welding process in which a metal electrode is held so that the
heat of the arc fuses both the electrode and the work to form a weld.
METALLIZING:
A method of overlay or metal bonding to repair worn parts.
MIXING CHAMBER:
That part of a welding or cutting torch in which the gases are mixed for
combustion.
MULTI-IMPULSE WELDING:
The making of spot, projection, and upset welds by more than one
impulse of current. When alternating current is used each impulse may
consist of a fraction of a cycle or a number of cycles.
NEUTRAL FLAME:
A gas flame in which the oxygen and acetylene volumes are balanced
and both gases are completely burned.
NICK BREAK TEST:
A method for testing the soundness of welds by nicking each end of
the weld, then giving the test specimen a sharp hammer blow to break
the weld from nick to nick. Visual inspection will show any weld
defects.
NONFERROUS:
Metals which contain no iron. Aluminum, brass, bronze, copper, lead,
nickel, and titanium are nonferrous.
NORMALIZING:
Heating iron-base alloys to approximately 100 °F (38 °C) above the
critical temperature range followed by cooling to below that range in
still air at ordinary temperature.
NUGGET:
The fused metal zone of a resistance weld.
OPEN CIRCUIT VOLTAGE:
163
The voltage between the terminals of the welding source when no
current is flowing in the welding circuit.
OVERHEAD POSITION:
The position in which welding is performed from the underside of a
joint and the face of the weld is approximately horizontal.
OVERLAP:
The protrusion of weld metal beyond the bond at the toe of the weld.
OXIDIZING FLAME:
An oxyacetylene flame in which there is an excess of oxygen. The
unburned excess tends to oxidize the weld metal.
OXYACETYLENE CUTTING:
An oxygen cutting process in which the necessary cutting temperature
is maintained by flames obtained from the combustion of acetylene
with oxygen.
OXYACETYLENE WELDING:
A welding process in which the required temperature is attained by
flames obtained from the combustion of acetylene with oxygen.
OXY-ARC CUTTING:
An oxygen cutting process in which the necessary cutting temperature
is maintained by means of an arc between an electrode and the base
metal.
OXY-CITY GAS CUTTING:
An oxygen cutting process in which the necessary cutting temperature
is maintained by flames obtained from the combustion of city gas with
oxygen.
OXYGEN CUTTING:
A process of cutting ferrous metals by means of the chemical action of
oxygen on elements in the base metal at elevated temperatures.
OXYGEN GOUGING:
An application of oxygen cutting in which a chamfer or groove is
formed.
OXY-HYDROGEN CUTTING:
An oxygen cutting process in which the necessary cutting temperature
is maintained by flames obtained from the combustion of city gas with
oxygen.
OXY-HYDROGEN WELDING:
A gas welding process in which the required welding temperature is
attained by flames obtained from the combustion of hydrogen with
oxygen.
OXY-NATURAL GAS CUTTING:
164
An oxygen cutting process in which the necessary cutting temperature
is maintained by flames obtained by the combustion of natural gas with
oxygen.
OXY-PROPANE CUTTING:
An oxygen cutting process in which the necessary cutting temperature
is maintained by flames obtained from the combustion of propane with
oxygen.
PASS:
The weld metal deposited in one general progression along the axis of
the weld.
PEENING:
The mechanical working of metals by means of hammer blows.
Peening tends to stretch the surface of the cold metal, thereby relieving
contraction stresses.
PENETRANT INSPECTION:
a. Fluorescent. A water washable penetrant with high fluorescence and
low surface tension. It is drawn into small surface openings by
capillary action. When exposed to black light, the dye will fluoresce.
b. Dye. A process which involves the use of three noncorrosive liquids.
First, the surface cleaner solution is used. Then the penetrant is applied
and allowed to stand at least 5 minutes. After standing, the penetrant is
removed with the leaner solution and the developer is applied. The dye
penetrant, which has remained in the surface discontinuity, will be
drawn to the surface by the developer resulting in bright red
indications.
PERCUSSIVE WELDING:
A resistance welding process in which a discharge of electrical energy
and the application of high pressure occurs simultaneously, or with the
electrical discharge occurring slightly before the application of
pressure.
PERLITE:
Perlite is the lamellar aggregate of ferrite and iron carbide resulting
from the direct transformation of austenite at the lower critical point.
PITCH:
Center to center spacing of welds.
PLUG WELD:
A weld is made in a hole in one member of a lap joint, joining that
member to that portion of the surface of the other member which is
exposed through the hole. The walls of the hole may or may not be
parallel, and the hole may be partially or completely filled with the
weld metal.
165
POKE WELDING:
A spot welding process in which pressure is applied manually to one
electrode. The other electrode is clamped to any part of the metal much
in the same manner that arc welding is grounded.
POROSITY:
The presence of gas pockets or inclusions in welding.
POSITIONS OF WELDING:
All welding is accomplished in one of four positions: flat, horizontal,
overhead, and vertical. The limiting angles of the various positions
depend somewhat as to whether the weld is a fillet or groove weld.
POSTHEATING:
The application of heat to an assembly after a welding, brazing,
soldering, thermal spraying, or cutting operation.
POSTWELD INTERVAL:
In resistance welding, the heat time between the end of weld time, or
weld interval, and the start of hold time. During this interval, the weld
is subjected to mechanical and heat treatment.
PREHEATING:
The application of heat to a base metal prior to a welding or cutting
operation.
PRESSURE CONTROLLED WELDING:
The making of a number of spot or projection welds in which several
electrodes function progressively under the control of a pressure
sequencing device.
PRESSURE WELDING:
Any welding process or method in which pressure is used to complete
the weld.
PREWELD INTERVAL:
In spot, projection, and upset welding, the time between the end of
squeeze time and the start of weld time or weld interval during which
the material is preheated. In flash welding, it is the time during which
the material is preheated.
PROCEDURE QUALIFICATION:
The demonstration that welds made by a specific procedure can meet
prescribed standards.
PROJECTION WELDING:
A resistance welding process between two or more surfaces or between
the ends of one member and the surface of another. The welds are
localized at predetermined points or projections.
PULSATION WELDING:
166
A spot, projection, or seam welding process in which the welding
current is interrupted one or more times without the release of pressure
or change of location of electrodes.
PUSH WELDING:
The making of a spot or projection weld in which the force is aping
current is interrupted one or more times without the release of pressure
or change of location of electrodes.
PUSH WELDING:
The making of a spot or projection weld in which the force is applied
manually to one electrode and the work or a backing bar takes the
place of the other electrode.
QUENCHING:
The sudden cooling of heated metal with oil, water, or compressed air.
REACTION STRESS:
The residual stress which could not otherwise exist if the members or
parts being welded were isolated as free bodies without connection to
other parts of the structure.
REDUCING FLAME:
See CARBONIZING FLAME.
REGULATOR:
A device used to reduce cylinder pressure to a suitable torch working
pressure.
REINFORCED WELD:
The weld metal built up above the surface of the two abutting sheets or
plates in excess of that required for the size of the weld specified.
RESIDUAL STRESS:
Stress remaining in a structure or member as a result of thermal and/or
mechanical treatment.
RESISTANCE BRAZING:
A brazing process in which bonding is produced by the heat obtained
from resistance to the flow of electric current in a circuit of which the
workpiece is a part, and by using a nonferrous filler metal having a
melting point above 800 °F (427 °C), but below that of the base metals.
The filler metal is distributed in the joint by capillary attraction.
RESISTANCE BUTT WELDING:
A group of resistance welding processes in which the weld occurs
simultaneously over the entire contact area of the parts being joined.
RESISTANCE WELDING:
A group of welding processes in which fusion is produced by heat
obtained from resistance to the flow of electric current in a circuit of
which the workpiece is a part and by the application of pressure.
167
REVERSE POLARITY:
The arrangement of direct current arc welding leads in which the work
is the negative pole and the electrode is the positive pole of the
welding arc.
ROCKWELL HARDNESS TEST:
In this test a machine measures hardness by determining the depth of
penetration of a penetrator into the specimen under certain arbitrary
fixed conditions of test. The penetrator may be either a steel ball or a
diamond spherocone.
ROOT:
See ROOT OF JOINT and ROOT OF WELD.
ROOT CRACK:
A crack in the weld or base metal which occurs at the root of a weld.
ROOT EDGE:
The edge of a part to be welded which is adjacent to the root.
ROOT FACE:
The portion of the prepared edge of a member to be joined by a groove
weld which is not beveled or grooved.
ROOT OF JOINT:
That portion of a joint to be welded where the members approach
closest to each other. In cross section, the root of a joint may be a
point, a line, or an area.
ROOT OF WELD:
The points, as shown in cross section, at which the bottom of the weld
intersects the base metal surfaces.
ROOT OPENING:
The separation between the members to be joined at the root of the
joint.
ROOT PENETRATION:
The depth a groove weld extends into the root of a joint measured on
the centerline of the root cross section.
SCARF:
The chamfered surface of a joint.
SCARFING:
A process for removing defects and checks which develop in the
rolling of steel billets by the use of a low velocity oxygen deseaming
torch.
SEAL WELD:
A weld used primarily to obtain tightness and to prevent leakage.
SEAM WELDING:
168
Welding a lengthwise seam in sheet metal either by abutting or
overlapping joints.
SELECTIVE BLOCK SEQUENCE:
A block sequence in which successive blocks are completed in a
certain order selected to create a predetermined stress pattern.
SERIES WELDING:
A resistance welding process in which two or more welds are made
simultaneously by a single welding transformer with the total current
passing through each weld.
SHEET SEPARATION:
In spot, seam, and projection welding, the gap surrounding the weld
between faying surfaces, after the joint has been welded.
SHIELDED WELDING:
An arc welding process in which protection from the atmosphere is
obtained through use of a flux, decomposition of the electrode
covering, or an inert gas.
SHOULDER:
See ROOT FACE.
SHRINKAGE STRESS:
See RESIDUAL STRESS.
SINGLE IMPULSE WELDING:
The making of spot, projection, and upset welds by a single impulse of
current. When alternating current is used, an impulse may consist of a
fraction of a cycle or a number of cycles.
SIZE OF WELD:
a. Groove weld. The joint penetration (depth of chamfering plus the
root penetration when specified).
b. Equal leg fillet welds. The leg length of the largest isosceles right
triangle which can be inscribed within the fillet weld cross section.
c. Unequal leg fillet welds. The leg length of the largest right triangle
which can be inscribed within the fillet weld cross section.
d. Flange weld. The weld metal thickness measured at the root of the
weld.
SKIP SEQUENCE:
See WANDERING SEQUENCE.
SLAG INCLUSION:
Non-metallic solid material entrapped in the weld metal or between the
weld metal and the base metal.
SLOT WELD:
A weld made in an elongated hole in one member of a lap or tee joint
joining that member to that portion of the surface of the other member
169
which is exposed through the hole. The hole may be open at one end
and may be partially or completely filled with weld metal. (A fillet
welded slot should not be construed as conforming to this definition.)
SLUGGING:
Adding a separate piece or pieces of material in a joint before or during
welding with a resultant welded joint that does not comply with design
drawing or specification requirements.
SOLDERING:
A group of welding processes which produce coalescence of materials
by heating them to suitable temperature and by using a filler metal
having a liquidus not exceeding 450 °C (842 °F) and below the solidus
of the base materials. The filler metal is distributed between the closely
fitted surfaces of the joint by capillary action.
SOLIDUS:
The highest temperature at which a metal or alloy is completely solid.
SPACER STRIP:
A metal strip or bar inserted in the root of a joint prepared for a groove
weld to serve as a backing and to maintain the root opening during
welding.
SPALL:
Small chips or fragments which are sometimes given off by electrodes
during the welding operation. This problem is especially common with
heavy coated electrodes.
SPATTER:
The metal particles expelled during arc and gas welding which do not
form a part of the weld.
SPOT WELDING:
A resistance welding process in which fusion is produced by the heat
obtained from the resistance to the flow of electric current through the
workpieces held together under pressure by electrodes. The size and
shape of the individually formed welds are limited by the size and
contour of the electrodes.
SPRAY TRANSFER:
A type of metal transfer in which molten filler metal is propelled
axially across the arc in small droplets.
STAGGERED INTERMITTENT FILLET WELD:
Two lines of intermittent welding on a joint, such as a tee joint,
wherein the fillet increments in one line are staggered with respect to
those in the other line.
STORED ENERGY WELDING:
170
The making of a weld with electrical energy accumulated
electrostatically, electromagnetically, or electrochemically at a
relatively low rate and made available at the required welding rate.
STRAIGHT POLARITY:
The arrangement of direct current arc welding leads in which the work
is the positive pole and the electrode is the negative pole of the
welding arc.
STRESS RELIEVING:
A process of reducing internal residual stresses in a metal object by
heating to a suitable temperature and holding for a proper time at that
temperature. This treatment may he applied to relieve stresses induced
by casting, quenching, normalizing, machining, cold working, or
welding.
STRING BEAD WELDING:
A method of metal arc welding on pieces 3/4 in. (19 mm) thick or
heavier in which the weld metal is deposited in layers composed of
strings of beads applied directly to the face of the bevel.
STUD WELDING:
An arc welding process in which fusion is produced by heating with an
electric arc drawn between a metal stud, or similar part, and the other
workpiece, until the surfaces to be joined are properly heated. They are
brought together under pressure.
SUBMERGED ARC WELDING:
An arc welding process in which fusion is produced by heating with an
electric arc or arcs between a bare metal electrode or electrodes and the
work. The welding is shield by a blanket of granular, fusible material
on the work. Pressure is not used. Filler metal is obtained from the
electrode, and sometimes from a supplementary welding rod.
SURFACING:
The deposition of filler metal on a metal surface to obtain desired
properties or dimensions.
TACK WELD:
A weld made to hold parts of a weldment in proper alignment until the
final welds are made.
TEE JOINT:
A joint between two members located approximately at right angles to
each other in the form of a T.
TEMPER COLORS:
The colors which appear on the surface of steel heated at low
temperature in an oxidizing atmosphere.
TEMPER TIME:
171
In resistance welding, that part of the postweld interval during which a
current suitable for tempering or heat treatment flows. The current can
be single or multiple impulse, with varying heat and cool intervals.
TEMPERING:
Reheating hardened steel to some temperature below the lower critical
temperature, followed by a desired rate of cooling. The object of
tempering a steel that has been hardened by quenching is to release
stresses set up, to restore some of its ductility, and to develop
toughness through the regulation or readjustment of the embrittled
structural constituents of the metal. The temperature conditions for
tempering may be selected for a given composition of steel to obtain
almost any desired combination of properties.
TENSILE STRENGTH:
The maximum load per unit of original cross-sectional area sustained
by a material during the tension test.
TENSION TEST:
A test in which a specimen is broken by applying an increasing load to
the two ends. During the test, the elastic properties and the ultimate
tensile strength of the material are determined. After rupture, the
broken specimen may be measured for elongation and reduction of
area.
THERMIT CRUCIBLE
The vessel in which the thermit reaction takes place.
THERMIT MIXTURE:
A mixture of metal oxide and finely divided aluminum with the
addition of alloying metals as required.
THERMIT MOLD:
A mold formed around the parts to be welded to receive the molten
metal.
THERMIT REACTION:
The chemical reaction between metal oxide and aluminum which
produces superheated molten metal and aluminum oxide slag.
THERMIT WELDING:
A group of welding processes in which fusion is produced by heating
with superheated liquid metal and slag resulting from a chemical
reaction between a metal oxide and aluminum, with or without the
application of pressure. Filler metal, when used, is obtained from the
liquid metal.
THROAT DEPTH:
In a resistance welding machine, the distance from the centerline of the
electrodes or platens to the nearest point of interference for flatwork or
172
sheets. In a seam welding machine with a universal head, the throat
depth is measured with the machine arranged for transverse welding.
THROAT OF FILLET WELD:
a. Theoretical. The distance from the beginning of the root of the joint
perpendicular to the hypotenuse of the largest right triangle that can be
inscribed within the fillet-weld cross section.
b. Actual. The distance from the root of the fillet weld to the center of
its face.
TOE CRACK:
A crack in the base metal occurring at the toe of the weld.
TOE OF THE WELD:
The junction between the face of the weld and the base metal.
TORCH:
See CUTTING TORCH or WELDING TORCH.
TORCH BRAZING:
A brazing process in which bonding is produced by heating with a gas
flame and by using a nonferrous filler metal having a melting point
above 800 °F (427 °C), but below that of the base metal. The filler
metal is distributed in the joint of capillary attraction.
TRANSVERSE SEAM WELDING:
The making of a seam weld in a direction essentially at right angles to
the throat depth of a seam welding machine.
TUNGSTEN ELECTRODE:
A non-filler metal electrode used in arc welding or cutting, made
principally of tungsten.
UNDERBEAD CRACK:
A crack in the heat affected zone not extending to the surface of the
base metal.
UNDERCUT:
A groove melted into the base metal adjacent to the toe or root of a
weld and left unfilled by weld metal.
UNDERCUTTING:
An undesirable crater at the edge of the weld caused by poor weaving
technique or excessive welding speed.
UPSET:
A localized increase in volume in the region of a weld, resulting from
the application of pressure.
UPSET WELDING:
A resistance welding process in which fusion is produced
simultaneously over the entire area of abutting surfaces, or
progressively along a joint, by the heat obtained from resistance to the
173
flow of electric current through the area of contact of those surfaces.
Pressure is applied before heating is started and is maintained
throughout the heating period.
UPSETTING FORCE:
The force exerted at the welding surfaces in flash or upset welding.
VERTICAL POSITION:
The position of welding in which the axis of the weld is approximately
vertical. In pipe welding, the pipe is in a vertical position and the
welding is done in a horizontal position.
WANDERING BLOCK SEQUENCE:
A block welding sequence in which successive weld blocks are
completed at random after several starting blocks have been
completed.
WANDERING SEQUENCE:
A longitudinal sequence in which the weld bead increments are
deposited at random.
WAX PATTERN:
Wax molded around the parts to be welded by a thermit welding
process to the form desired for the completed weld.
WEAVE BEAD:
A type of weld bead made with transverse oscillation.
WEAVING:
A technique of depositing weld metal in which the electrode is
oscillated. It is usually accomplished by a semicircular motion of the
arc to the right and left of the direction of welding. Weaving serves to
increase the width of the deposit, decreases overlap, and assists in slag
formation.
WELD:
A localized fusion of metals produced by heating to suitable
temperatures. Pressure and/or filler metal may or may not be used. The
filler material has a melting point approximately the same or below
that of the base metals, but always above 800 °F (427 °C).
WELD BEAD:
A weld deposit resulting from a pass.
WELD GAUGE:
A device designed for checking the shape and size of welds.
WELD METAL:
That portion of a weld that has been melted during welding.
WELD SYMBOL:
A picture used to indicate the desired type of weld.
WELDABILITY:
174
The capacity of a material to form a strong bond of adherence under
pressure or when solidifying from a liquid.
WELDER CERTIFICATION:
Certification in writing that a welder has produced welds meeting
prescribed standards.
WELDER PERFORMANCE QUALIFICATION:
The demonstration of a welder's ability to produce welds meeting
prescribed standards.
WELDING LEADS:
a. Electrode lead. The electrical conductor between the source of the
arc welding current and the electrode holder.
b. Work lead. The electrical conductor between the source of the arc
welding current and the workpiece.
WELDING PRESSURE:
The pressure exerted during the welding operation on the parts being
welded.
WELDING PROCEDURE:
The detailed methods and practices including all joint welding
procedures involved in the production of a weldment.
WELDING ROD:
Filler metal in wire or rod form, used in gas welding and brazing
processes and in those arc welding processes in which the electrode
does not provide the filler metal.
WELDING SYMBOL:
The assembled symbol consists of the following eight elements, or
such of these as are necessary: reference line, arrow, basic weld
symbols, dimension and other data, supplementary symbols, finish
symbols, tail, specification, process, or other references.
WELDING TECHNIQUE:
The details of a manual, machine, or semiautomatic welding operation
which, within the limitations of the prescribed joint welding procedure,
are controlled by the welder or welding operator.
WELDING TIP:
The tip of a gas torch especially adapted to welding.
WELDING TORCH:
A device used in gas welding and torch brazing for mixing and
controlling the flow of gases.
WELDING TRANSFORMER:
A device for providing current of the desired voltage.
WELDMENT:
An assembly whose component parts are formed by welding.
175
WIRE FEED SPEED:
The rate of speed in mm/sec or in./min at which a filler metal is
consumed in arc welding or thermal spraying.
WORK LEAD:
The electric conductor (cable) between the source of arc welding
current and the workpiece.
X-RAY:
A radiographic test method used to detect internal defects in a weld.
YIELD POINT:
The yield point is the load per unit area value at which a marked
increase in deformation of the specimen occurs with little or no
increase of load; in other words, the yield point is the stress at which a
marked increase in strain occurs with little or no increase in stress.
APPENDIX2. КЛАССИФИКАЦИЯ ВИДОВ И СПОСОБОВ СВАРКИ
Таблица 1. Классификация сварки металлов по ГОСТ 19521-74
Класс сварки
Термический
Термомеханический
Определение
Виды сварки,
осуществляемы
плавлением с
использованием
тепловой энергии
Виды сварки,
осуществляемые с
использованием
тепловой энергии и
давления
176
Вид сварки
дуговая,
электрошлаковая,
электронно-лучевая,
плазменно-лучевая,
ионно-лучевая,
тлеющим разрядом,
световая,
индукционная,
газовая, термитная,
литейная.
контактная,
диффузионная,
индукционнопрессовая,
газопрессовая,
термокомпрессионная,
дугопрессовая,
шлакопрессовая,
термитно-прессовая,
печная
Механический
Виды сварки,
осуществляе мые с
использованием ме
ханической энергии и
дав ления
холодная, взрывом,
ультразвуковая,
трением, магнитноимпульсная.
Таблица 2. Термины и определение сварочных материалов по ГОСТ
2601-84
Термин
Определение
Сварочная проволока Проволока для использования в качестве
плавящегося электрода либо присадочного
металла при сварке плавлением
Электродная
Сварочная проволока для использования в
проволока
качестве плавящегося электрода
Присадочная
Сварочная проволока, используемая как
проволока
присадочный металл и не являющаяся
электродом
Самозащитная
Электродная проволока, содержащая вещества,
проволока
которые защищают расплавленный металл от
вредного воздействия воздуха при сварке
Порошковая
Сварочная проволока, состоящая из
проволока
металлической оболочки, заполненной
порошкообразными веществами
Неплавящийся
Деталь из электропроводного материала,
электрод для дуговой включаемая в цепь сварочного тока для подвода
сварки
его к сварочной дуге и не расплавляющаяся при
сварке
Плавящийся электрод Металлический электрод, включаемый в цепь
для дуговой сварки
сварочного тока для подвода его к сварочной
дуге, расплавляющийся при сварке и служащий
присадочным металлом
Покрытый электрод
Плавящийся электрод для дуговой сварки,
имеющий на поверхности покрытие,
адгезионно связанное с металлом электрода
Покрытие электрода
Смесь веществ, нанесенная на электрод для
усиления ионизации, защиты от вредного
воздействия среды, металлургической
обработки сварочной ванны
177
Таблица 3. Сварные соединения и швы
Сварное соединение
Стыковое соединение
неразъемное соединение, выполненное сваркой
двух элементов, примыкающих друг к другу
торцевыми поверхностями
Угловое соединение
двух элементов, расположенных под углом и
сваренных в месте примыкания их краев
Нахлесточное
соединение
в котором сваренные элементы расположены
параллельно и частично перекрывают друг
друга
Тавровое соединение
в котором торец одного элемента примыкает
под углом и приварен к боковой поверхности
другого элемента
в котором боковые поверхности сваренных
элементов примыкают друг к другу
Торцевое соединение
Сварная конструкция
металлическая конструкция, изготовленная
сваркой отдельных деталей
Сварной узел
часть конструкции, в которой сварены
примыкающие друг к другу элементы
Сварной шов
участок сварного соединения, образовавшийся в
результате кристаллизации расплавленного
металла или пластической деформации при
сварке давлением или сочетания
кристаллизации и деформации
Проход при сварке
однократное перемещение в одном направлении
источника теплоты при сварке и (или) наплавке
Основной металл
Металл подвергающихся сварке соединяемых
частей
Глубина проплавления Наибольшая глубина расплавления основного
металла в сечении шва или наплавленного
валика
Сварочная ванна
Часть металла свариваемого шва, находящаяся
при сварке плавлением в жидком состоянии
Присадочный металл
Металл для введения в сварочную ванну в
178
Наплавленный металл
Металл шва
Угар при сварке
Свариваемость
Сварочный флюс
Флюс для дуговой
сварки
дополнение к расплавленному основному
металлу
Переплавленный
присадочный
металл,
введенный
в
сварочную
ванну
или
наплавленный на основной металл
Сплав, образованный расплавленным основным
и наплавленным металлами или только
переплавленным основным металлом
Потери металла на испарение и окисление при
сварке
Металлический
материал
считается
поддающимся сварке до установленной степени
при данных процессах и для данной цели, когда
сваркой достигается металлическая целостность
при
соответствующем
технологическом
процессе, чтобы свариваемые детали отвечали
техническим требованиям как в отношении их
собственных качеств, так и в отношении их
влияния на конструкцию,которую они образуют
Материал, используемый при сварке для
химической очистки соединяемых
поверхностей и улучшения качества шва
Сварочный флюс, защищающий дугу и
сварочную ванну от вредного воздействия
окружающей среды
179
REFERENCES
1. ASM International (2003). Trends in Welding Research. Materials Park,
Ohio: ASM International. - ISBN 0871707802
2. Assessment of Exposure to Fume from Welding and Allied Processes,
HSE Books, 1990.
3. Blunt, Jane and Nigel C. Balchin (2002). Health and Safety in Welding
and Allied Processes. Cambridge: Woodhead. - ISBN 1855735385
4. Brightmore A. D., Bernasek M. Moving Weld Management from the Desk
to the Desktopю Using "expert" software packages, computers can make life
easier for the welding engineer. - http://www.cspec.com/csp-paper.htm1.
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6. Cary, Howard B. and Scott C. Helzer (2005). Modern Welding
Technology. Upper Saddle River, New Jersey: Pearson Education. - ISBN
0131130295
7. Kalpakjian, Serope and Steven R. Schmid (2001). Manufacturing
Engineering and Technology. Prentice Hall.- ISBN 0201361310.
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(2005) 77s-85s.
9. Hicks, John (1999). Welded Joint Design. New York: Industrial Press. ISBN 0831131306.
10. Lincoln Electric (1994). The Procedure Handbook of Arc Welding.
Cleveland: Lincoln Electric. - ISBN 9994925822.
11. Modern Welding by Althouse, Turnquist, and Bowditch. The GoodheartWillcox Co. 1970
12. Robot welding. - http://www.robot-welding.com
13. The American Welding Society. - http://www.aws.org
180
14. The Control of Exposure to Fume from Welding, Brazing and Similar
Processes, HSE Books, 1990.
15. The Welding Encylopedia, The Welding Engineer staff, ninth ed. 1938
16. The Welding Institute. - http://www.twi.co.uk
17. Weman, Klas (2003). Welding processes handbook. New York: CRC
Press LLC. - ISBN 0849317738.
18. Welding in Space. http://www.thefabricator.com/Articles/Welding_Article.cfm?ID=553
19. Welding Handbook Vol. 2 Library of Congress number 90-085465
copyright 1991 by American Welding Society
20. Welding handbook Volume 2, eighth edition.'' Library of Congress
number: 90-085465 copyright 1991 by American Welding Society
Occupation Exposure Limits, HSE Books.
21. Технология электрической сварки плавлением / Под. ред.
Е.Е.Патона. – М.: Государственное научно-техническое издательство
машиностроительной литературы. – 664 с.
22. Хромченко Ф.А. Сварочное пособие электросварщика. – М.:
Машиностроение, 2003. – 420 с.
181
NOTES
182
NOTES
183
Сергей Владимирович Гричин
АНГЛИЙСКИЙ ДЛЯ СВАРЩИКОВ
Учебное пособие
Научный редактор
кандидат технических наук
Д.А. Чинахов
Корректор
Т.В. Казанцева
Подписано к печати 18.04.2007г.
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Плоская печать. Усл. печ. л.10,70 . Уч.-изд. л. 9,67 .
Тираж экз. 100. Заказ 674. Цена свободная.
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184
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