Пособие для сварщиков

Пособие для сварщиков
МИНИСТЕРСТВО НАУКИ И ОБРАЗОВАНИЯ
РОССИЙСКОЙ ФЕДЕРАЦИИ
Государственное образовательное учреждение высшего профессионального образования
«НАЦИОНАЛЬНЫЙ ИССЛЕДОВАТЕЛЬСКИЙ
ТОМСКИЙ ПОЛИТЕХНИЧЕСКИЙ УНИВЕРСИТЕТ»
ЮРГИНСКИЙ ТЕХНОЛОГИЧЕСКИЙ ИНСТИТУТ
___________________________________________________________________________________________
С.В. Гричин, О.В. Ульянова
АНГЛИЙСКИЙ ЯЗЫК
ДЛЯ ИНЖЕНЕРОВ СВАРОЧНОГО
ПРОИЗВОДСТВА
Рекомендовано Сибирским региональным учебно-методическим центром
высшего профессионального образования для межвузовского
использования в качестве учебного пособия
для студентов, обучающихся по специальности 150202
«Оборудование и технология сварочного производства»
Издательство
Томского политехнического университета
2011
УДК 811 (Англ.)(075)
ББК 81.2я73
Г 82
Гричин С.В., Ульянова О.В.
Г 82
Английский язык для инженеров сварочного производства:
учебное пособие / С.В. Гричин, О.В. Ульянова; Юргинский технологический институт. – Томск: Изд-во Томского политехнического университета, 2011. – 164с.
Пособие содержит аутентичные тексты на английском языке,
посвященные вопросам сварочного производства; упражнение направленные
на развитие навыков чтения и устной речи по профессиональной тематике, а
также приложения.
Предназначено для студентов вузов, обучающихся по специальности
150202 «Оборудование и технология сварочного производства».
УДК 811 (Англ.)(075)
ББК 81.2я73
Рецензенты
Доктор педагогических наук, профессор,
зав.кафедрой иностранных языков КузГТУ
Л.С. Зникина
Кандидат педагогических наук
зав.кафедрой английского языка
и технической коммуникации ИМОЯК ТПУ
Л.В. Малетина
Кандидат педагогических наук
Доцент кафедры ГОИЯ ЮТИ ТПУ
А.А. Нагорняк
© ГОУ ВПО НИ ТПУ Юргинский
технологический институт (филиал), 2011
© Гричин С.В., Ульянова О.В., 2011
© Обложка. Издательство Томского
политехнического университета, 2011
2
CONTENTS
Введение (Preface)
4
PART 1. Job description and welding education
5
PART 2. The history of welding
24
PART 3. Welding processes & equipment
40
PART 4. Arc and gas welding in detail
51
PART 5. Modern developments
73
PART 6. Health, safety and accident prevention
96
PART 7. Advanced technologies and the future of welding
106
APPENDIX 1. Welding theory & application definitions
125
APPENDIX 2. Классификация видов и способов сварки
154
APPENDIX 3. Аннотирование и реферирование
158
REFERENCES
162
3
ВВЕДЕНИЕ
Данное учебное пособие предназначено для подготовки по
английскому
языку
студентов
высших
учебных
заведений,
обучающихся по специальности 150202 «Оборудование и технология
сварочного производства». Пособие нацелено на обучение студентов 2 –
3 курсов, уже изучивших базовый курс иностранного языка в вузе и
владеющих основами грамматики и лексики общелитературного
английского языка. В пособие включены аутентичные тексты на
английском языке по основной сварочной тематике, снабженные
упражнениями и заданиями, направленными на развитие навыков
чтения, реферирования и аннотирования литературы по специальности,
а также устной речи на профессиональные темы и некоторых видов
письма.
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
рассчитано
на
60–70
самостоятельной работы студентов.
4
часов
аудиторной
и
PART 1. JOB DESCRIPTION AND WELDING EDUCATION
Lead-in
1
From the list below choose the places where welders are not likely to
work.
Ø machine-building factory workshop
Ø bridge construction site
Ø hospital
Ø university department
Ø shipyard
Ø bank
Ø repair shop
Ø assembly site
Ø bakery
2
Choose the correct word or both to complete the definition of welding.
Welding is the process of cutting/joining pieces of metal/plastic
detachably/permanently with metal/ceramic filler, using heat/pressure.
Reading 1
3
Before you read do the self-rating. Answer the questions about you.
Are you good at preparing and planning a job from start to
finish?
Can you look at a diagram or shop drawing and visualize how
things come together?
Do you like figuring out what’s wrong with something and
then repairing it?
Are you able to bend, stretch, kneel, stand for long periods
and lift material and supplies?
Would it bother you to work around dangerous gases and
intense heat?
Do you have good hand/eye coordination to guide a welding
arc along the edges of metal?
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
If you answered Yes to most of these questions, welder may be for you!
5
4
Read the text Welding & Machine Trades and fill in the table with the
information from the text.
Welding
professions
and levels
Personal qualities
Places/fields
Trades
where welding a welder can a welder should
have
work at (in)
skill is used
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.
6
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
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.
Vocabulary
weld
repair and maintenance
sheet metal work
ironworker
glazier
tender
supervisor
contractor
repair shop
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) работы по жести
металлург
стекольщик
1) лицо, присматривающее за кем-л.,
обслуживающее кого-л., что-л. 2) механик,
оператор
контролер
подрядчик, контрактор
ремонтная мастерская
наладка [настройка] станка
1) неразрушающие испытания;
2) неразрушающий контроль
5
Find Russian equivalents for the words and phrases in italics. Write
them out into your dictionary
6
Answer the following questions on the text.
1. What are the trades where welding skills are used?
7
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?
7
Translate the following sentences from Russian into English:
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.
Speaking
8
Discuss with a partner what the following specialists do. Ask and
answer questions according to the model.
- What does a welder do?
- A welder uses some of various welding processes to join units of
metal.
Ø welder
Ø welding machine operator
Ø welding technician
Ø welding schedule developer
8
Ø welding procedure writer
Ø testing laboratory technician
Ø welding non destructive testing inspector
Writing
11
Write five sentences (one per each paragraph) summarizing the main
ideas of the text.
Reading 2
12
Before you read say if the following statements are true or false.
1. Welding is an important process employed by modern industry.
2. All welding processes are similar.
3. All welding processes require workpieces 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.
13
Read the text What is welding and what do welders do? Check your
answers in the previous exercise. Prove or correct the statements.
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
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.
9
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 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.
10
14
Find the English equivalents for the following words and word
combinations.
Валовой национальный продукт, на открытом воздухе, в помещении,
космический корабль, горное оборудование, изношенные детали,
домашние принадлежности.
15
Complete the following sentences with the information from the text.
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 … . Another group involves … .
Speaking
16
Divide into two groups. Name as many uses of welding as you can
remember without looking into the text. Each correct sentence gets a point to
your group.
Begin your sentences like this:
Welders help …
Welders are employed in …
Welders are involved in …
Welders perform …
Reading and speaking
17
Look at the list of types of welding and say which of them you can use.
Types of welding
Ø gas tungsten arc
welding (GTA)
Ø tungsten inert gas
welding (TIG)
Ø shielded metal
arc welding
(SMAW)
Ø electroslag
welding
Ø submerged arc
сварка неплавящимся электродом
дуговая сварка вольфрамовым электродом в среде
инертного газа
дуговая сварка покрытым металлическим
электродом
электрошлаковая сварка
(дуговая) сварка под флюсом
11
welding (SAW)
Ø termite welding
Ø alternating
current welding
Ø resistance
welding
термитная сварка
сварка на переменном токе
(контактная) сварка сопротивлением
18 Look at the list of skills and say if you need all of them for your future
job.
Job Related Skills, Interests and Values
Ø using and maintaining tools, material handling equipment and welding
equipment;
Ø reading and interpreting blueprints;
Ø laying out, cutting and forming metals to specifications;
Ø preparing the work site;
Ø fitting sub-assemblies and assemblies together and preparing
assemblies for welding ;
Ø carrying out special processes such as welding studs and brazing;
Ø ensuring quality of product/process before, during and after welding;
Vocabulary
blueprint
brazing
welding studs
19
1) делать светокопию, копировать чертеж
2) делать разметку
пайка твердым припоем (из меди и цинка)
приварка шпилек плавлением
Speak about your professional skills. Begin like this.
I can use …
I’m learning to carry out…
I want to master using …
20
Read about welders’ training, career possibilities and wage rate in the
USA and compare with those in your country.
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.
Completion of an apprenticeship could take approximately 3 years including
12
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 can be in the non-electrical, machinery,
construction and metal-fabricating industries. Some workers will become
self-employed.
What is the Wage Rate for Welders?
As an apprentice you would start at a wage rate less than that of a
journeyperson. This rate increases gradually as you gain competency. 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.
Vocabulary
journeyman (person)
apprentice
plate working
наемный квалифицированный рабочий
ученик
обработка листового металла
Speaking
21
Complete the sentences to speak about your country.To become a
Welder you should complete …
Training (apprenticeship) could take …
Upon successful completion of the training, you will receive …
Most welders work (full-time/ part-time/ in shift work/ indoors/ outdoors/
self-employed)
As an apprentice you would start at a wage rate of …
The wage range for fully qualified welders is …
13
Reading 3
22
Imagine you are choosing a welding course. First choose what you
want to learn from the list(1-7). Then read the information in the table below
and choose the course to your needs.
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.
Welding Education and Consultation Training Centre
Course
Course Objectives
Course Outlines
Materials properties related to
Welding
The main objective of this
welding. Welding process
Design
course is to introduce
selection. Types of welded
welding engineers to the
joints. Welding Accessibility
subject of welding design.
and Inspection. Economical
Many factors have to be
Analysis. Design information.
considered in this issue.
Welding symbols. Case
These factors include:
studies.
consumer requirement,
technical specifications, and
environmental and
economical constrains
Welding processes: Shielded
Welding
The main objective of this
metal Arc welding, Arc
Fundamentals course is to familiarize
engineers and inspectors to welding, Gas tungsten Arc
welding, Submerged Arc
various aspects related to
welding & Oxyfuel welding &
welding techniques,
electric resistance. Cutting
inspection and quality
processes: Oxygen cutting,
procedures in welding
plasma cutting and laser
industry. The course is
cutting. Inspection of
designed for engineers of
weldments: Nondestructive
scientists with no or little
testing of welments.
experience in the welding
Mechanical testing of
field.
14
Welding
Inspection
weldments (tensile, bending,
impact).
Significance of weld
The course discusses both
qualification inspections and discontinuities. Welding
inspection (non-destrutive
on-line inspections of
welded joints. These include testing techniques: surface
inspection, magnetic particle,
mechanical tests (tension,
volumetric, radiography, and
bending, impact, ...etc, and
ultrasonic). Destructive testing
non destructive tests.
techniques: hardness, tension,
bending, ...etc. The control of
quality during shop operations.
The control of quality during
site welding.
Non
Destructive
testing
Certification:
Magnetic
Particle &
Liquid
Penetrant
Testing (MT
& PT)
Level I: Is to train inspectors
to be able to pass level I
examination and to be able
to inspect using the chosen
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
15
Physical principals of test.
Processing. Test equipment
and materials. Codes,
standards, procedures and
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
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
process for specific
application. Welding
processes discussed include:
SMAW, GMAW, GTAW,
etc.
The highest level of
certification in the field of
welding
AWS
Certified
welding
Engineer
Vocabulary
technique
case study
oxyfuel
tensile test
bending test
impact test
discontinuity
volumetric
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
welding. Flame and arc cutting
of metals. Computer
applications in welding. Case
studies.
To get certified as a welding
engineer you need to attend
four exams: Fundamentals of
science. Applied science.
Fundamentals of welding.
Applied welding.
1) техника, способ, технические приемы 2) метод,
методика,
учебный пример, разбор конкретного случая
газоплазменный
испытание на растяжение
испытание на изгиб
испытание на ударную вязкость
отсутствие непрерывности, нарушение
последовательности, несплошность
объемный
16
hardness
tension
site welding
heat flow
heat treatment
welding metallurgy
hardenability
weldability
non-ferrous
alloy
ASME
AWS
23
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
сплав
сокр. от American Society of Mechanical Engineers
Американское общество инженеров-механиков
сокр. от American Welding Society Американское
сварочное общество
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.
24
Match the words (a-h) with definitions (1-8).
a) alloy, b) joint, c) inspection, d) welding, e) laser, f) property, g) plasma,
h) arc
1. Joining pieces of metal (or nonmetal) at faces rendered plastic or liquid by
heat or pressure (or both).
17
2. A junction or mode of joining parts together; b) the place where two things
are joined together
3. The luminous arc or bridge across a gap between two electrodes when an
electric current is sent through them.
4. A careful, narrow or critical examination or survey; b) an official
examination.
5. An instrument which amplifies light waves by stimulation to produce a
powerful, coherent beam of monochromatic light, an optical maser.
6. Metal blended with some other metallic or nonmetallic substance to give it
special qualities, such as resistance to corrosion, greater hardness, or tensile
strength.
7. Peculiar or inherent quality.
8. A hot, ionized gas containing approximately equal numbers of positive
ions and electrons.
Writing
25
Make a description of the welding course you are following at the
University. Use the information in Activity 22 as an example.
The name of the course
The course description
The course outline
…
…
…
Reading 4
26
You will read a text about underwater welding. Before you read make
a list of questions which you would ask about this career opportunity if you
were going to try it.
27
Read questions (A – F) commonly asked by those who have expressed
an interest in underwater welding, but were unsure how to get start. Then
read the answers (1 – 6) provided by AWS. Match each question with the
suitable answer. The first is done.
A.
What are the age limitations of a welder-diver?
B.
I am already a certified diver, what other training do I need to qualify
as a welder-diver?
18
C.
What skills are prerequisite to entering the field of underwater
welding?
D.
What salary can I expect to make as a welder-diver?
E.
I am a certified surface welder, what other training do I need to qualify
as a welder-diver?
F.
What future career opportunities are there for an experienced welderdiver?
Taking the Plunge:
A Guide to Starting an Underwater Welding Career
1
C
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 welder-diver 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
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
suggested that a dive physical be taken regardless, to avoid going through the
19
expense of training only to later find you have a disability that prevents your
entering the profession.
3
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
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 examination. The
commercial diving profession is physical demanding. It is rare to see an
active commercial welder-diver over the age of 50.
5
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
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.
20
Industry has and will continue to demand higher quality standards for
underwater welds and more certification of underwater welding systems and
personnel.
Vocabulary
subsea
rigging
fitter
alignment
beveling
stripping
patch
scuba diver
draft
lapse
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
делать чертеж, проектировать
юр. прекращение, недействительность права (на
что-л.)
28
Give Russian equivalents to the words in italics.
29
Continue filling in the following table:
Operations both surface welders Operations only welder-divers do
and welder-divers do
weld setup and preparation, …
underwater cutting, …
30
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.
21
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.
31
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?
32
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.
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.
Speaking
33
Discuss the following questions in the group.
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?
22
Revision
Name five
Ø types of welding
Ø places where welders can work
Ø welding professions
Ø welding courses
Ø job related skills
23
PART 2. THE HISTORY OF WELDING
Lead-in
1
Look at pictures A, B, C of welded constructions and define what time
period they refer to.
Picture A
Picture B
Picture C
Reading 1
2
You will read the text Welding History - A Story of Harnessing Heat.
Before you read check your knowledge of welding history by doing the short
test below.
1. The history of welding began in
a) the Bronze Age
b) the Middle Ages
c) the 19th century
d) the 20 century
24
2. All of the following improvements of the welding process refer to the 20th
century EXEPT
a) covered electrode
b) electric arc
c) shielding gas
d) automatic welding
3. The invention attributed to a Russian inventor Benardos is
a) carbon electrode
b) acetylene
c) resistance welding
d) alternating current welding
4. The latest welding process having been introduced is
a) electrogas welding
b) laser beam welding
c) flux-cored arc welding
d) electroslag welding
3
Read the text and check your answers in the previous exercise.
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
25
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.
Termite 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.
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
26
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.
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.
Vocabulary
forge
oxyacetylene
porosity
brittleness
shielding gas
welding rod
MIG
выковывать, ковать
1) автогенный 2) кислородно-ацетиленовый
пористость
хрупкость
защитный газ
сварочный пруток
metal inert gas welding сварка металлическим
электродом в инертном газе
27
torch
molten pool/puddle
impurities
4
горелка
сварочная ванна, ванна жидкого металла
примеси
Find equivalents for the following words combinations in the text.
Tорговое судоходство, открытая печь, военный самолет, открытый горн,
источник тепла, признавать преимущества, высокая стоимость,
приводить к увеличению скорости сварки, оказаться особенно
полезным.
5
Fill in the table with the scientists’ names and their inventions from the
lists below.
Scientists: Edmund Davy; A. P. Strohmenger; Jones, Kennedy and
Rothermund; Benardos; C.J. Holslag; Oscar Kjellberg; Alexander; Nikolai
Slavyanov and C.L. Coffin.
Inventions: discovered acetylene; invented the electric arc; developed metal
electrode; brought a coated metal electrode; invented and patented the
covered electrode; invented alternating current; developed Submerged Arc
Welding; patented Atomic Hydrogen Welding process.
Date
1540
Scientist
Vannoccio Biringuccio
1800
1800s.
1836
1881
Sir Humphrey Davy;
Invention
described forging operation
demonstrated the welding process
with carbon electrode
1900
1904
1919
1935
1924
28
6
Say if the following is true or false. Correct the false statements.
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. Oxygen is used as shielding gas in TIG welding.
5. The TIG process made it possible to construct planes faster.
7
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?
8
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.
29
Reading 2
9
Read the text From the History of Welding and refer the statements
1-4 to each of the passages of the text A-D
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.
From the History of Welding
A
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.
B
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.
C
Modern fusion welding processes are an outgrowth of the need to
obtain a continuous joint on large steel plates. Riveting 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
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
30
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.
D
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 solid-phase
processes such as diffusion bonding, friction welding, and ultrasonic joining
have been developed.
Vocabulary
armour
carburization
interlayering
high-carbon
hammer forging
cast iron
blacksmith
jeweler
riveting
boiler
oxyacetylene
consumable
bare
coating
spot
seam
sheet
butt
tungsten
bonding
броня
науглероживание
чередование слоев
высокоуглеродистый
свободная ковка на молоте
чугун
кузнец
ювелир
производить клёпку
паровой котёл, бойлер
ацетилено-кислородный
расходуемый
непокрытый
покрытие
точечная
роликовая
лист
стыковая
вольфрам
соединение, (с)крепление, связывание
10
Find the English equivalents for the following word combinations in
the text.
Сварочная технология, твердое железо, кухонная утварь, листовая
сталь,
сложное покрытие,
алюминиевая проволока,
острая
необходимость, проволока без покрытия.
31
11
Say if the following is true or false. Correct the false sentences.
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.
8. Riveting is now widely used for producing an enclosed container such as a
boiler.
12
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?
13
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.
32
Writing
14
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.
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.
.Project work
15
Read about The ASME Code. Find out the content of the ASME code.
Make a presentation or a report.
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
33
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. "
Reading 3
16
You will read four texts about Welding's Vital Part in Major
American Historical Events. Before you read suggest your answers to 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?
17
Look through the texts and find out what the following figures relate to.
140 20 5171 2200
500,000 586,000 17,000
1945 525 531 2710
80 373 500 52 48,6
120
176,000
Model: 2200 - 2200 passengers were killed on the Mississippi River when
the steamboat Sultana blew up.
34
18
Divide into four groups, each group reading one of the four texts. Fill
in the table below for your text.
Time period
Branch
Industry
of Types of welding
Achievements
Welding's Vital Part
in Major American Historical Events
1
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
an arrestor. This safeguard helped reduce casualties from 140 to 20 per
month.
35
2
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 Moss-Rosenberg 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.
3
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
36
finish. At one point, 17,000 people were working on the pipeline - 6% of the
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.
4
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
37
steel were used in that section. Webs and flanges for each interior H column
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."
Vocabulary
war effort
brittle fracture
notch
crack propagation
field welding
toughness
planeload
X-ray inspection
induction heating
structural steel
rolled steel
fillet weld
contact face
военная экономика
хрупкий излом
зубец, вырез, паз, пропил, прорез
развитие трещин
сварка в полевых условиях, сварка при монтаже
твердость
полная загрузка самолета
рентгенодефектоскопия
индукционный нагрев
конструкционная сталь
стальной прокат
угловой сварной шов
поверхность контакта
38
Speaking
19
Use the information in the table as a plan and speak about the
achievement you have read about to the class.
Revision
Name:
Ø a method to protect welds from the effects of oxygen and nitrogen in
the atmosphere
Ø the inventions in welding attributed to Russian scientists
Ø the code providing safety for construction of pressure-related items
Ø some recently developed types of welding
39
PART 3. WELDING PROCESSES & EQUIPMENT
Lead-in
1
There are processes similar to welding which a welder should know
about. Read the definitions of metal joining processes (1-6) and supply them
with Russian equivalents from the list (a-f).
a) резка
b) пайка мягким (легкоплавким) припоем
c) свинцевание
d) клепка
e) лужение
f) пайка твердым припоем резка
1. 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.
2. Tinning: A soldering process, where the surface of a metal is coated with
solder.
3. Leading: A form of soldering, solder is used to fill in the surface of metal.
4. 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.
5. Cutting: Work is heated to melting point and beyond, and "cut" by
oxidizing metal. (Literally burning it away).
6. Riveting: A process of fastening with a rivet which is a heavy pin having a
head at one end and the other end being hammered flat after being passed
through holes in the pieces that are fastened together.
2
Remember the definition of welding and say what the main difference
between welding and related metal joining processes is.
Reading 1
3
You will read the text Basic Principles of Welding.
Before you read list all the ways of generating heat for welding.
Ways of Generating Heat for Welding
1. Electric arc
…
…
40
4
Read the text and answer the 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?
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.
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.
41
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.
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
42
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.
Vocabulary
coalescence
molten pool
gas flame
solid-phase
ultrasonic
friction
furnace
diffusion
high-current
low-voltage
discharge
arc column
direct current (dc)
alternating current
layer
molten-metal
droplet
inert atmosphere
annulus
torch
base metal
grain
precipitation
residual stress
соединение, слипание, сращение
ванна расплавленного металла, сварочная ванна
газовое пламя
твёрдая фаза
ультразвуковой
трение
печь
1) рассеивание 2) диффузия
сильноточный
низковольтный, низкого напряжения
разряд
столб дуги
постоянный ток
(ac)переменный ток
слой, пласт, ряд
капля жидкого металла
инертная среда
тех. узкое кольцо (зазор и т. п.)
сварочная горелка (для автоматической сварки –
головка)
основной металл
зерно
осаждение
остаточное напряжение
43
5
Find the English equivalents for the following words and word
combinations.
Pасплавленный металл, необходимый размер, 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.
6
Complete the following sentences.
1. A characteristic feature of fusion welding is:
a) molten metal
b) low-voltage discharge
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.
7
Say if the following sentences are 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.
44
Writing
8
Write a short report on the subject below.
Function of Fluxes and Inert Atmosphere in Welding
Reading and speaking
9
Study the Master Chart of the Principal Welding Processes (Chart
1) and complete the 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 … .
10
Describe the classification of pressure processes. Use the verbs in bold
from the previous exercise.
45
46
Reading 2
11
You will read the text Alternative Types of Welding. Before you read
suggest your answers to the following questions.
1. What is the difference between the principle (“traditional”) and alternative
types of welding?
2. Why are traditional welding processes not sufficient?
12
Match welding types (1-6) with their description (A-F). Then read the
text and check your answers.
1. Cold welding
2. Friction welding
3. Laser welding
4. Diffusion bonding
5. Ultrasonic welding
6. Explosive 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.
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.
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.
47
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 work-piece 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
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
48
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.
Vocabulary
cold welding
lapped joints
diffusion bonding
ultrasonic welding
explosive welding
butt
anvil
honeycomb
fin
finished
integrated circuitry
pneumatic tooling
punch presses
13
холодная сварка (в вакууме)
соединение внахлестку
диффузное соединение
ультразвуковая сварка
сварка взрывом
стык
наковальня
пористый
ребро, пластина
готовый, обработанный
интегральная схемотехника
пневматический инструмент
пресс-штамп
Fill in the blanks with the right words (namely, types of welding).
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.
49
14
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 является
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.
Speaking
15
Choose an alternative welding method for the following applications.
Explain your choice.
Ø
Ø
Ø
Ø
to join some electrical wires to form a circuit
a transistor can
parts of a plane which have honeycomb construction
to join two aluminum sheets laid one onto another
Revision
16
In each line of words (1-4) find the odd one out. Explain your choice.
1
2
3
4
low-voltage, gas flame, direct current, discharge
gas welding, arc welding, … termit welding, resistance welding
friction, torch, flux, filler material
fusion, filler, heat-affected, unaffected
50
PART 4. ARC AND GAS WELDING IN DETAIL
Lead-in
1
Remember the definition and description of arc welding from the
previous part. What, in your opinion, makes arc welding one of the two main
welding processes so widely applied in modern industry?
Reading 1
2
Study the ways of compression of information in Appendix 3. Read
Russian texts(A-D) below and say what type of compression they are.
A
В тексте описываются 2 основных метода сварки неплавящимся
электродом: дуговая сварка вольфрамовым электродом в защитном газе,
отличающаяся стабильностью дуги и, таким образом, обеспечивающая
возможность сварки тонких листов металла, и плазменная сварка, более
скоростная и применяющаяся для сварки материалов большей толщины.
Приводятся типичные сферы применения данных разновидностей
сварки.
B
В тексте описывается возможное вредное влияние сварки на
здоровье человека. Отмечается, что снижение влияния вредных
факторов при сварке достигается благодаря применению специальной
экипировки и других средств защиты. Особое внимание уделяется
предотвращению вредного воздействия на человеческий организм
выделяемых газов. Отмечается высокий риск возникновения пожара
вследствие использования легковоспламеняющихся материалов и
кислорода.
C
В тексте приводятся сведения о применяемых в электродуговой
сварке различных видaх электропитания. Описывается обусловленность
выбора различных источников электропитания при ручном и
автоматическом режимах сварки. В зависимости от выбранного
источника, а также от полярности электрода и основного металла,
показываются возможные особенности процесса сварки, что позволяет
сделать правильный выбор указанных параметров для получения
сварного шва.
D
В тексте описаны 3 основных вида сварки с использованием
плавящегося электрода: дуговая сварка металлическим покрытым
51
электродом, дуговая сварка металлическим электродом в среде
инертного газа и дуговая сварка под флюсом. Подробное описание
каждой из данных разновидностей сопровождается перечислением их
преимуществ и недостатков, пригодности использования в зависимости
от типа свариваемого материала, требований к квалификации сварщика,
экономичности, скорости и других параметров.
Skim the English texts (1-4)(Power Supplies, Consumable Electrode
Method, Non-consumable Electrode Method, Safety Issues), and match
them and Russian texts (A-D) in the previous activity.
1
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.
Fig. 1 A constant current welding
Constant current power supplies are most
power supply capable of AC and DC
often used for manual welding processes
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
52
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
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.
2
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
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,
53
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.
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.
3
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
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
54
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.
4
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.
3
Read the texts above and find the English equivalents for the following
Russian phrases in the text.
Положительно заряженный анод, остатки флюса, волна типа
"синусоида", гармоническая волна/ прямоугольная волна, плавящийся
55
электрод, свариваемые металлы, пересечение нулевого уровня, пленка
ПВХ, светофильтры, наплавка, горючие материалы
4
Say if the following statements are true or false. Correct the false
sentences.
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.
7. Submerged arc welding is used to weld large work pieces.
5
Answer the following questions on 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?
6
Match the terms (1-10) and their meanings (A-J).
1. Anode
2. Ultraviolet
(UV) light
3. Flux
A Electromagnetic radiation with a wavelength shorter than
that of visible light, but longer than soft X-rays.
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
current in an electrical conductor.
C Electrical current whose magnitude and direction vary
cyclically, as opposed to direct current, whose direction
remains constant.
56
4. Alternating
current (AC)
5. Oxidation
6. Goggles and
safety glasses
7. Toxicity
8. Stainless
steel
9. Arc eye
10. Voltage
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 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.
G Loss of an electron by a molecule, atom or ion
H also known as arc flash, welder's flash, corneal flash
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.
I 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.
J 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.
57
7
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.
Speaking
8
Explain to a non-specialist the difference between consumable
electrode method and non-consumable electrode methods.
Reading 2
9
Below you will 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.
58
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
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
59
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.
10
Write a brief summary to the text in the previous activity.
11
Say if the following is true or false. Correct the false sentences.
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.
12
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?
60
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?
13
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
14
Write a short report about arc welding. Include the items below.
Ø Types (SMAW, MMA, GMAW, MIG, FCAW, SAW, GTAW, TIG,
electroslag welding, stud arc welding, EGW)
Ø Types of filler material used (consumable/none-consumable,
covered/bare electrode/wire)
Ø Type of current used (direct/alternating)
Ø Type of shielding gas used (helium, argon, CO2)
Ø Major application areas
Speaking
15
Discuss the following questions in the group.
1. What is the difference in methods of gas cutting and gas welding?
2. Is there any difference in equipment used for gas welding and gas cutting?
3. What might be the advantages and disadvantages of gas cutting compared
to other methods of cutting metals?
4. Do you remember what appeared before: arc or gas welding?
5. What type of cutting (arc or gas) is :
a) more expensive
b) more operator skills demanding
c) safer
e) faster
61
f) more precise?
6. Do you know what metals (steels) are better cut using gas welding?
16
Look at the picture of Oxygas Cutting Equipment (Fig. 3) and tell
about its design. The phrases below will help you.
The oxygas cutting equipment consists of …
The main parts of the equipment are …
It also has …
… are installed on (at) …
Fig. 2 Oxygas cutting outfit
62
Reading 3
17
Read about welding gases and fill in the table.
Acetylene
Mapp Gas
Chemical composition
Flame temperature
Colour and odor
Stability (temperature)
Cylinder packing
Dangerous effects on
health
Acetylene
Fig. 3
Portable welding outfit
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 4 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 selfexplosive 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.
63
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 highpressure gas pockets forming
in the cylinder.
Fig. 4
Acetylene 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.
An example of an acetylene cylinder is shown in figure 5. 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.
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.
64
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
Fig. 5 Compressed gas
characteristic odor, while harmless, gives
cylinders containing
oxygen oxygen and MAPP warnings of fuel leaks in the equipment long
before a dangerous condition can occur. MAPP
gas
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.
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.
Speaking
18
Discuss in the group advantages and disadvantages of using Acetylene
and map gas. Say which gas you would prefer to use for gas welding and
why.
Reading 4
19
Skim the two texts Regulators and Cutting Torches and write
annotations.
65
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.
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.
66
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
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
Fig. 6 One piece oxygas cutting torch
welding tips or a
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.
67
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 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.
Fig. 7 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.
Vocabulary
rig
hose
spark
какое-л. приспособление, устройство, механизм
Syn: apparatus , device
шланг
искра
68
igniter
wrench
outfit
pressure gauge
leak
orifice
single-stage
(regulator)
flashback
20
воспламенитель
гаечный ключ
агрегат, оборудование, принадлежности, набор
(приборов, инструментов)
манометр
течь, протечка, утечка
отверстие
однокамерный
обратный удар пламени (проникающий в шланг
сварочной горелки)
Read the texts above more carefully and complete the sentences.
1. The most common devices for pressure reduction are … and …
2. Regulators control pressure and …
3. Regulators have two gauges: one is for indicating the cylinder pressure and
the other is for indicating …
4. Psig is an acronym from …
5. Psig is used to measure …
6. Valve leaks in regulators can be caused by …
7. A combination torch is a torch which can accept either welding tips or …
8. It is necessary to keep the tip orifices and passages clean and free of …
21
Look at the pictures of torches on pages 67-68 and tell about their
design.
Reading 5
22
Read the detailed instruction for Setting up the equipment for oxygas
welding and continue filling in the table below.
Instructions
(What should be done)
When using fuel and oxygen tanks
they should be fastened securely to a
wall, a post or a portable cart in an
upright position.
Precautions
(What shouldn’t be done)
An oxygen tank should never be
moved around without the valve cap
screwed in place.
69
Setting up the equipment
When using fuel and oxygen
tanks they should be fastened
securely to a wall, a post or a
Fig. 8
portable cart in an upright position.
Oxygen Rich Butane Blow Torch Flame 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.
Fig. 9
Never lay the acetylene tank
Fuel Rich Butane Blow Torch Flame down while being used, as the acetone
would start 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
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
70
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.
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'
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
71
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.
Speaking
23
Imagine you are explaining to an apprentice how to set up the
equipment. Use the right column of the table in the previous exercise and the
tips below to give the instructions.
First fasten fuel and oxygen tanks securely to a wall, a post or a portable cart
in an upright position.
Then remove … .
After that … .
…
…
Having attached ... .
…
…
…
…
After this preparation ... .
…
Finally … .
Revision
24
Decode the abbreviations.
SMAW, MMA, GMAW, MIG, FCAW, SAW, GTAW, TIG, EGW
25
Label the picture of a portable welding outfit with the words below.
header pipe
line valve
filler plug
release
regulator
escape pipe
flash arrestor chamber
check valve and drain plug
acetylene cylinder
Fig. 10
Portable welding outfit
72
PART 5. MODERN DEVELOPMENTS
Lead-in
1
In small groups discuss the trends of modern research in welding listed
below. Decide which of them are of primary importance. Think of some other
trends. Report to the class.
Ø
Ø
Ø
Ø
Ø
Ø
new welding methods
automation of welding
computer control
energy saving technologies
environmentally friendly technologies
safety improvements
Reading 1
2
You will read the text Friction Stir Welding (FSW). Before you read
discuss the following questions in the group.
1. Is the method of friction stir welding a conventional one?
2. What makes it conventional/unconventional?
3. What material does it best fit for?
3
Skim the text and make its brief summary.
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
73
maximum temperature reached is of the order of 0.8 of the melting
temperature.
Fig. 11 Tool in operation
Fig. 12 HAZ
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 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.
74
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
Fig. 13 Friction-stir
welding machine
Below you can see 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.
Fig. 14 The tools
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.
75
Fig. 15 The fixture
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.
Fig 16 Obtaining a weld
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
76
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.
Fig. 17
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.
77
Fig. 18 Optical micrographs of regions (a), (b) and (c) of the stir nugget.
The location 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.
Vocabulary
ductile
threaded
pin
shoulder
debris
volumetric
shrinkage
solute
equiaxed
гибкий, ковкий, поддающийся обработке
с резьбой, нарезной
цапфа
буртик, поясок
осколки, обломки, обрезки, лом
объемный
усадочная деформация
растворенное вещество, раствор
равноосный
4
Read the Russian text below and correlate it with the text Friction Stir
Welding (FSW) in the previous activity. Say if it is a good abstract for the
English text. Why? Why not?
78
Friction Stir Welding (FSW)
Сварка трением
H.H. Bhadeshia
Х.Х. Бхадешия
Метод сварки трением, разработанный транснациональной
корпорацией TWI (Кембридж, Великобритания) в 1991 г., заключается в
получении соединения металлов без использования плавления и
присадочных материалов. Данный метод получил широкое применение
для сварки металлических листов, однако он также может применяться
для сварки труб, полых секций и др. Сварной шов образуется благодаря
сочетанию фрикционного разогрева и механической деформации,
вызываемых вращающимся органом – цапфой. Максимально
достижимая температура составляет порядка 0,8 от температуры
плавления.
Рабочий орган имеет круглое сечение, на конце которого
расположен зонд с насечкой. Стык цилиндрической части с зондом
называют буртиком. Зонд проникает в свариваемые поверхности, в то
время как буртик производит трение по поверхности. Тепло
вырабатывается главным образом в результате трения рабочего органа о
поверхность свариваемых листов металла.
По завершении шва рабочий орган отводят, на месте его работы
остается отверстие. Поскольку образующееся отверстие недопустимо
при сварке труб, его образования можно избежать применением
специальной конструкции рабочего органа, в котором цапфа
автоматически плавно втягивается в буртик, оставляя после себя
неповрежденный шов.
5
Read the text carefully and answer the following questions.
1. What is 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?
6
Say if the following is true or false. Correct the false sentences.
1. FSW is not used to weld steels.
2. It’s impossible to avoid holes in welds made by FSW method.
79
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.
Reading and speaking
7
In small groups read the characteristics of FSW given below and
distribute them into two categories in the table. Compare with other groups.
Then speak about advantages and disadvantages of FSW.
Advantages
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Ø
Disadvantages
The method requires a stable welding machine with a powerful fixture.
Material from 15-30 mm can be welded on both sides.
No joint preparation, only degreasing.
The method can only be used on straight, flat workpieces or hollow
profiles with an abutment or backing.
High, consistent quality.
No grinding or brushing.
No consumables.
No shielding gas.
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.
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.
Material thickness from 1.6-15 mm can be welded as single-pass
procedures.
80
Ø The back of the object must be accessible if 100% penetration is
necessary.
Ø The welding equipment should preferably be stationary.
Vocabulary
abutment
backing
degreasing
magnetic blowing
торец; упор; опора,
опора
обезжиривание
магнитное срывание дуги
8
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, environmentallycompatible.
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 … .
Writing
81
9
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.
Reading 2
10
You will read the text Man-machine Communication for Multi-run Arc
Welding. Before you read discuss the following questions in the group.
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?
11
Read the text and answer 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?
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
82
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
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
83
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.
Vocabulary
run
man-machine
communication
welding sequence
non-destructive testing
interpass temperature
weld bead
log file
проход
интерфейс человек-машина
последовательность сварки, порядок наложения
швов
испытания
без
разрушения
образца,
неразрушающий контроль
температура
начала
мартенситных
превращений
наплавленный валик сварного шва
системный журнал
Speaking
12
Specify the functions of:
Ø Remote control box
Ø Weld Report
Ø Log File
13
Use the verbs from the left column and the phrases from the right column
to speak about advantages of automated welding systems.
a) good overview of important events during
1 to provide
2 to allow
welding
3 to enable the operator
b) valuable information for the planning of non4 to result in
destructive testing
5 to offer
c)
easily-accessible documentation of the
welding process
d) to choose to stop the process immediately,
stop it after the completion of the bead or allow it
to continue
e) better weld quality
14
Translate the following sentences into English:
84
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.
10. Автоматизированная сварочная система обеспечивает успешное
осуществление сварочного процесса.
Reading 3
15
Make an abstract of the article IT in Welding and Cutting for the
Welding Engineer –PC Programs and the Internet
.
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.
85
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.
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;
86
· 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.
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.
87
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;
· 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 on the WWW
88
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;
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.
Vocabulary
89
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
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
получать доступ
Writing
16
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.
Ø What kind of software is available for welding engineers?
Ø How can welders get access to welding related information?
Ø How can computers improve the work of welders?
Ø What welding procedures can be best computerized?
Reading 4
90
17
Read the first part of the article Moving Weld Management from the
Desk to the Desktop and say if the following is 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.
3. Most existing software systems in the fabrication industry are tools for
large companies.
4. The first database management systems could not create new procedures
for new application.
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
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.
91
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.
18
Read the second part of the article and answer the 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?
92
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
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:
93
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.
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
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
94
original WPS, for repair purposes, or the NDE report, to see if evidence of
the defect was present at testing.
Vocabulary
storage
database
filing cabinet
power generation
bottleneck
хранение
база данных
1) шкаф для хранения документов; 2) картотека,
каталог
производство электроэнергии
узкое место
19
Make an abstract of the two parts of the article Moving Weld
Management from the Desk to the Desktop
Revision
20
Make a short description of Friction Stir Welding 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.
95
PART 6. HEALTH, SAFETY AND ACCIDENT PREVENTION
Lead in
1
Discuss in the group.
1. Do you think welding is a dangerous/hazardous profession?
2. What type/types of welding do you consider the most/least hazardous?
Why?
Reading 1
2
Look through the text Health Risks of Welding Fume/Gases and list
the risks generated during welding.
Health Risks of 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;
96
- 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 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.
97
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
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.
98
Chart 2
Occupational Exposure Limits
Substances Assigned a Maximum Exposure
Limit
8hr TWA
Beryllium
0.002
mg/m 3
Cadmium oxide fume (as Cd)
0.025
mg/m 3
15 min
STEL
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
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.
99
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.
Vocabulary
irritation
respiratory tract
susceptibility
fever
tickling
chest tightness
flu
coughing
limb
siderosis
pneumonia
pulmonary
oedema
asphyxiation
exposure
cancer
3
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
Read the text carefully and 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?
100
4
Say if the following is true or false. Correct the false sentences.
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.
5
Complete the following sentences.
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 … .
Reading 2
6
Read the text Safety and Scheduled Maintenance Protect Your
Welding Assets and say if you follow all the instructions during welding.
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.
101
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
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
102
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
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.
Vocabulary
bare spot
оголенный участок
wire feeder
механизм подачи (электродной или присадочной)
проволоки
ground
1) заземление, замыкание на землю 2) соединение на
connection
корпус
power
switch
переключатель мощности
rupture
1) пробой (изоляции); 2) излом, разрушение, разрыв
confined
замкнутый объём, замкнутое пространство
space
exhaust
вытяжной шкаф; вытяжной колпак
hood
7
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.
103
Speaking
8
Answer each of the questions in text 6 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.
Reading and speaking
9
Below is a general engine drive routine daily maintenance schedule.
Read the information in the chart and say what a welder should do in terms
of maintenance
Ø once a working day;
Ø once a week;
Ø once a month.
Chart 3
Maintenance Schedule Chart
8 Hours
50 Hours
100
Hours
200
Hours
250
Hours
500
Hours
1000
Hours
10
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?
104
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?
11
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.)
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 … .
Revision
12
Describe in detail the welding procedure which you are most
experienced in. Follow the plan.
Ø
Ø
Ø
Ø
Ø
the task to do
the equipment required
work stages
safety measures
quality control
105
PART 7. ADVANCED TECHNOLOGIES
AND THE FUTURE OF WELDING
Lead-in
1
Read the two opinions about the future of welding and say which one
you support.
The future looks promising for
welding. It remains and will
continue to be a productive,
cost-effective manufacturing
method.
As far as design will be more and
more efficient there will be no
need in joining parts by means of
welding and it will see decline in
use.
Reading 1
2
You will read the text “The past, present and future of aerospace join
processes”. Before you read suggest your answers to 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?
3
Read the text again and say what events relate to:
Ø the past
Ø the present
Ø the future
Fill the table. Some examples are given.
The past
The present
verifying the possibility testing in a flying
of thermal-cutting and laboratory
welding in space
106
The future
completely new methods
of nondestructive testing
and diagnosing welded
structures
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, lowpressure 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
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
107
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
opinion existed that this process, which involves high-accelerating voltage,
the possibility of X-ray radiation 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).
108
Based on new engineering systems that corrected technical parameters
and suppositions 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.
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.
109
Vocabulary
instrumentation
reflecting shield
preventive maintenance
arc discharge
globular
retrofitting
deposition
5
оснащение инструментами, приборами,
аппаратурой,
комплект
инструментов,
аппаратура
отражающий экран
профилактическое обслуживание
дуговой электрический разряд
шаровидный, сферический, сфероидальный,
шарообразный
подгонка, настройка
осаждение
Say if the following is 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.
6
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.
110
6. Специфика используемого на космических кораблях оборудования
обусловливает необходимость использования, прежде всего, ручной
сварки при частичной автоматизации процесса.
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.
Reading 2
7
You will read the text What Is Orbital Welding. Before you read think
and say why this type of welding is called “orbital”. Read the opening
paragraph and check your supposition.
Read the text and say what the main advantages of this method are.
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
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
111
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
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.
112
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.
Vocabulary
down-hand welding
celestial body
bend load
welding sequence
tensile load
pressure load
root pass
tolerance
manual welding
post-polishing
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
113
tack weld
X-ray testing
(qualification)
high duty
clamping fixture
DIN
ID
U-shape (bend)
grinding
weld seam
filler wire
saw blade
bevelling
performance capabilities
прихваточный сварной шов, прихватка
рентгеновская дефектоскопия
жесткий режим
прижимное устройство
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
8
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,
недопустимое качество сварки, квалифицированный сварщик,
содержание серы, механическая прочность, искусственный спутник,
система высокой очистки воды, обязательное условие.
9
Characterize orbital welding by filling in the right side of the
following table.
Parameter
Principle of the process
Description
An arc travels circumferentially
around a work piece (usually a tube or
pipe).
Category
Application areas
Limitations
114
10
Say if the following is 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.
Speaking
11
Describe Orbital welding by completing the following sentence.
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
… .
Reading 3
12
You will read an interview with industry leaders who speak about
future of welding.
Before you read predict which processes will be used more and which less in
the future. Then read the text and compare our predictions with those in the
text.
Ø
Ø
Ø
Ø
Ø
plasma arc welding
gas tungsten arc welding (GTAW)
continuous wire processes (FCAW, GMAW)
laser beam welding process
friction stir welding
115
Ø shielded metal arc welding (SMAW)
Ø resistance welding gas metal arc (GMAW)
Ø capacitor discharge welding
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
116
marketing North America, ESAB Welding and Cutting Products, replied,
"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
117
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.
118
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.
- What are the strengths of the welding industry? What are its
weaknesses?
119
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.
"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
120
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?
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."
121
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."
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?"
122
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.
13
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
“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
123
continue to provide opportunities for of gas metal arc (GMAW) and gas
tungsten arc welding (GTAW).
growth.
3. …
3. …
Speaking
14
Comment on the predictions. Say if you agree or disagree with each of
them and why. The phrases below will help you.
Meaning
Agreeing
Disagreeing
Saying you
partly agreed
Formal
This is absolutely right.
This is true.
I agree with you.
I suppose you may be right.
I’m afraid I can’t agree with you.
This is not quite right.
I’m not sure you are right about …
are I partly agree, but …
I suppose so, but …
I agree up to a point
124
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
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.
125
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
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.
126
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.
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
127
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
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.
128
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.
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.
129
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
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.
130
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
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.
131
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
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.
132
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
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
133
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
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
134
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
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
135
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
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.
136
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
The time that pressure is maintained at the electrodes after the welding
current has stopped.
137
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
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.
138
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
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.
139
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
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.
140
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
An oxygen cutting process in which the necessary cutting temperature
is maintained by flames obtained by the combustion of natural gas with
oxygen.
141
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.
142
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.
143
PULSATION WELDING
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.
144
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.
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.
145
SEAL WELD
A weld used primarily to obtain tightness and to prevent leakage.
SEAM WELDING
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.
146
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
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.
147
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
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.
148
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.
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.
149
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
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.
150
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
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.
151
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
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.
152
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.
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.
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.
153
APPENDIX2. КЛАССИФИКАЦИЯ ВИДОВ И СПОСОБОВ СВАРКИ
Таблица 1
Классификация сварки металлов по ГОСТ 19521-74
Класс сварки
Термический
Определение
виды сварки,
осуществляемы
плавлением с
использованием
тепловой энергии
Вид сварки
дуговая,
электрошлаковая,
электронно-лучевая,
плазменно-лучевая,
ионно-лучевая,
тлеющим разрядом,
световая,
индукционная,
газовая, термитная,
литейная.
Термомеханический
виды сварки,
осуществляемые с
использованием
тепловой энергии и
давления
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.
154
Таблица 2.
Термины и определение сварочных материалов по ГОСТ 2601-84
Термин
Сварочная проволока
Определение
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
деталь из электропроводного материала,
Неплавящийся
электрод для дуговой включаемая в цепь сварочного тока для подвода
его к сварочной дуге и не расплавляющаяся при
сварки
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
155
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
156
Присадочный металл
Наплавленный металл
Металл шва
Угар при сварке
Свариваемость
Сварочный флюс
Флюс для дуговой
сварки
Окончание таблицы 3
металл для введения в сварочную ванну в
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
157
APPENDIX 3 АННОТИРОВАНИЕ И РЕФЕРИРОВАНИЕ
РЕФЕРИРОВАНИЕ
Реферирование представляет собой интеллектуальный творческий
процесс,
включающий
осмысление,
аналитико-синтетическое
преобразование информации и создание нового документа – реферата,
обладающего специфической языково-стилистической формой.
Реферат (Abstract) – это семантически адекватное изложение
основного содержания первичного документа, отличающееся
экономной знаковой оформленностью постоянством лингвистических и
структурных характеристик и предназначенное для выполнения
разнообразных информационно-коммуникативных функций в системе
научной коммуникации.
Рефератом называется текст, передающий основную информацию
подлинника в свернутом виде и составленный в результате ее
смысловой переработки.
Особенности реферирования иностранных источников
Начиная работу над рефератом, переводчик должен, прежде всего,
правильно выбрать вид будущего реферата и наиболее целесообразный
способ охвата первоисточника.
Большое
значение имеет
информативность реферативных
переводов. Нельзя допустить, чтобы реферат был подменен развернутой
аннотацией, как это часто происходит при реферировании иностранных
источников. Необходимо передать не только то, о чем написана работа,
но и сущность основных идей оригинала, содержащихся в нем методов,
результатов, рекомендаций и предложений. Поэтому переводчик
должен быть хорошим специалистом в соответствующей области
знания и уметь выявлять наиболее информативные элементы текста.
Процесс работы над текстом первоисточника складывается из
нескольких этапов
1. Ознакомительное (ориентирующее) чтение, в результате
которого решается вопрос о целесообразности реферирования
иностранного материала. На этом этапе переводчик просматривает
заглавие, введение, оглавление, выводы, резюме. Затем он бегло читает
текст
и
определяет
научно-практическую
значимость
и
информационную новизну источника. Ключевые слова, содержащиеся в
заглавии, введении, рубриках оглавления,
выводах создают
содержательную установку, активизирующую в дальнейшем процесс
осмысления текста.
158
2. Анализ вида первоисточника и выбор аспектной схемы
изложения материала в будущем реферативном тексте (общий план
изложения, план изложения отраслевой методики реферирования и т.д.).
3. Изучающее чтение текста. Переводчик в данном случае не
делает
полного
письменного
перевода
текста.
Мысленное
декодирование иноязычного текста происходит под влиянием установки
на реферативный анализ. Необходимость выделения аспектов,
обозначенных в плане изложения, активизирует мыслительную
деятельность референта и придает ей поисковый характер.
5. Разбивка текста на «аспектные блоки» (разметка текста с
помощью удобных для референта-переводчика обозначений).
6. Конструирование (синтез) новых высказываний на родном языке,
в краткой лаконичной форме
передающих основное смысловое
содержание по каждому аспекту (Textrproduktion).
7. Запись фрагментов перевода, полученных в результате
вышеописанных преобразований, в последовательности, заданной
планом изложения.
8. Критическое сравнение текстов реферата и первоисточника с
позиции потребителя и внесение в случае необходимости изменений и
дополнений в текст реферата.
9. Оформление и редактирование реферата, когда переводчик
должен придерживаться наиболее распространенной структуры,
состоящей из трех элементов:
•
заголовочной
части
(библиографическое
описание
первоисточника);
• собственно реферативной части, передающей основное смысловое
содержание первоисточника;
• справочного аппарата (индекс, рубрикационный шифр,
информация о таблицах, чертежах, графиках, иллюстрациях и т.д.,
примечания переводчика, фамилия переводчика или название
организации, сделавшей перевод).
Таким образом, при реферировании речь идет, прежде всего, о
сплошном чтении первоисточника, касается ли это использования
текстовых частей документа или смысловой интерпретации текста.
Главное это выбор информации, относящейся к основным элементам
содержания документа, и наиболее компактное ее представление. Кроме
того,
в
процессе
реферирования
происходит
исключение
второстепенных, малосущественных сведений, не относящихся к
объекту исследования и его основным характеристикам.
159
АННОТИРОВАНИЕ
Аннотация (Summary) – это предельно сжатая характеристика
материала, заключающаяся в информации o затронутых в источниках
вопросах.
Аннотация включает характеристику основной темы, проблемы
объекта, цели работы и ее результаты. В аннотации указывают, что
нового несет в себе данный документ в сравнении с другими,
родственными по тематике и целевому назначению.
Виды аннотаций
Существуют различные виды аннотаций в зависимости от
назначения аннотации или от вида документа, на который составляется
аннотация.
С точки зрения объема аннотации подразделяются на краткие и
развернутые (или подробные).
Краткая аннотация, как правило, характеризует документ в
определенном аспекте – уточнение тематического содержания,
расшифровка или пополнение заглавия, оценка уровня материала и так
далее.
Развернутая аннотация часто представляет собой перечисление
рубрик первичного документа. Она составляется в тех случаях, когда
документ представляет значительный научный интерес, а также при
описании многоаспектных документов (учебники, справочники,
сборники и т.д.).
С точки зрения метода анализа и оценки документа аннотации
можно разделить на
описательные
(или справочные) и
рекомендательные (в том числе и критические).
Описательная аннотация дает общее представление о документе, в
то время как рекомендательная аннотация характеризует тематику и
содержание документа под определенным углом зрения.
В информационной сфере наибольшее применение находит
описательная аннотация.
В зависимости от тематического охвата содержания документа
аннотации делятся на общие и специализированные.
Общие аннотации характеризуют весь документ в целом, они не
ориентированы на определенный круг потребителей.
В специализированных аннотациях находят отражения только те
части, те аспекты содержания документа, которые интересуют
потребителей данной информационной системы (данного круга
читателей).
160
В информационной практике используется, как правило,
специализированная аннотация, рассчитанная на информирование
специалиста определенной отрасли научной или практической
деятельности. Такой вид аннотации целесообразен и при работе с
литературой в учебном процессе – при подготовке рефератов, докладов
и других научных работ студентами.
Этапы аннотирования
Аннотации всегда предпосылаются библиографические данные
первоисточника.
В аннотациях обычно содержатся следующие данные:
1) предметная рубрика;
2) тема;
3) сжатая характеристика материала;
4) выходные данные (автор и заглавие статьи, название и номер
периодического издания, где помещена статья, место и время издания).
161
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.
5. Canadian Welding Association. - http//www.cwa-acs.org
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.
8. Klingensmith, S., J. N. DuPont and A. R. Marder, Welding Journal, 84
(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
162
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.
Список литературы печатается в редакции авторов.
163
Учебное издание
ГРИЧИН Сергей Владимирович
УЛЬЯНОВА Ольга Викторовна
АНГЛИЙСКИЙ ЯЗЫК
ДЛЯ ИНЖЕНЕРОВ СВАРОЧНОГО ПРОИЗВОДСТВА
Учебное пособие
Научный редактор кандидат технических наук
доцент Д.А. Чинахов
Редактор Л.А. Холопова
Компьютерная верстка О.В. Ульянова
Подписано к печати 02.02.2010. Формат 60х84/16. Бумага «Снегурочка».
Печать RISO. Усл.печ.л. 9,59. Уч.-изд.л. 8,68.
Заказ 1172. Тираж 100 экз.
Национальный исследовательский
Томский политехнический университет
Система менеджмента качества
Томского политехнического университета сертифицирована
NATIONAL QUALITY ASSURANCE по стандарту ISO 9001:2000
. 634050, г. Томск, пр. Ленина, 30.
Тел/факс 8(3822)56-35-35, www.tpu.ru
164
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement