General Welding Guidelines - Mechanical Contractors Association

General Welding Guidelines - Mechanical Contractors Association
General Welding
Guidelines
National Certified
Pipe Welding Bureau
General Welding
Guidelines
National Certified
Pipe Welding Bureau
Revision date: April 2, 2013
© 2013
National Certified
Pipe Welding Bureau
1385 Piccard Drive
Rockville, MD 20850
301-869-5800
Fax: 301-990-9690
www.mcaa.org/ncpwb
The National Certified Pipe Welding Bureau (NCPWB)
gratefully acknowledges the permission from ASTM to use
their data on copper tube sizes in this publication.
CONTENTS
MANDATORY PRACTICES
General .............................................................................. 3
Joints ................................................................................. 3
Filler Metal ....................................................................... 3
Postweld Heat Treatment ................................................ 4
RECOMMENDED PRACTICES
General .............................................................................. 5
Joints ................................................................................. 5
Electrodes and Filler Metals ............................................ 8
Preheating and Interpass Temperature .......................... 9
Shielding and Backing Gas ............................................ 10
Cleaning .......................................................................... 13
Environmental Requirements ........................................ 14
Welding Technique ......................................................... 14
Welding From Two Sides................................................ 15
Visual Examination ........................................................ 16
Repairs ............................................................................ 18
Stamping of Welds .......................................................... 19
Safety .............................................................................. 19
Welding Hazards ............................................................ 20
Welding Lens Shades ..................................................... 21
ASME-P-Numbers .......................................................... 24
TABLES
Table 1, Low-Hydrogen Electrode Exposure Limits .......... 8
Table 2, Recommended Supplemental Preheat ............... 10
Table 3, Reinforcement-B31.1 Piping ............................... 17
Table 4, Reinforcement-B31.3 Piping ............................... 17
Table 5, Welding Lens Shade Selections .......................... 21
Table 6, Determining Purge Time .................................... 22
FORWARD
These General Welding Guidelines are intended to provide
background information and supplementary instructions to
contractors and their welders who are using National
Certified Pipe Welding Bureau Welding Procedures
Specifications (WPSs).
This document is divided into two sections: Mandatory
Practices and Recommended Practices.
The “Mandatory Practices” are in addition to the
instructions provided on the WPS and are considered part
of the requirements stated on the WPS.
The “Recommended Practices” provides additional
information to the welder on variables, which are not
covered in the WPS. These practices are recommended to
be followed unless other direction is provided by the
welder’s supervisor.
MANDATORY PRACTICES
General
All ASME Section IX variables are covered in the Welding
Procedure Specifications (WPSs). The welder shall follow the
instructions in the WPS when making Code welds.
In addition to the instructions in the WPSs, the following
portion of the General Welding Guidelines shall be followed
during all welding.
Joints
Unless specifically required by the WPS or by details on the
engineering drawings, the use of nonmetallic backing and
nonfusing metal retainers is not permitted. When backing is
shown as “Required” on the WPS, the backing shall be
backing ring or strip, or it shall be weld metal deposited by
another process or electrode type or the joint shall be made
from both sides of the joint (i.e., backwelded). Fillet welds
are considered welding on backing, and all sizes of fillet
welds may be made using any NCPWB WPS on any
thickness or diameter base metal.
Filler Metal
Welding without the addition of filler metal, such as might
be used for tight-butt welds on schedule 10 pipe or for wash
passes made on the cover to improve surface appearance, is
not permitted unless the WPS specifically permits welding
without the use of filler metal (i.e. the column “ROOT” on
the WPS has “NONE” for the filler metal.)
3
Postweld Heat Treatment
The required postweld heat treatment temperature range
indicated on the engineering drawing shall govern when
using a Welding Procedure Specification, which permits the
weld to be made either with or without heat treatment.
Postweld heat treatment holding time and heating and
cooling rates shall be in accordance with the applicable code
or contract requirements.
4
RECOMMENDED PRACTICES
General
The instructions contained in this portion of the guidelines
provide additional information to the welder concerning
variables, which are not usually addressed by the Welding
Procedures. The direction provided by the Welding
Procedure Specification and the “Mandatory Practices” in
this document constitute the minimum requirements for
code welding. The above requirements may not be changed
by the following “Recommended Practices” provided in this
document.
Joints
End preparations shall be in accordance with the details
provided in the construction drawing(s), or as provided on
the WPS. All groove welds shall be prepared and fit up in
such a way that a full penetration weld can be made except
where partial penetration welding is shown on the
construction or engineering drawing. This includes both
butt and branch connection welds on piping.
Care shall be taken when cutting the pipe to make the plane
of the cut square to the axis of the pipe, so that the flat land
and root spacing will be uniform all the way around the pipe.
End preparations shall be made by mechanical cutting or
flame cutting. Irregularities should be removed by grinding.
The bevel shall be uniform so that the resulting land is
uniform around the pipe. The finished surface shall be
reasonably smooth and suitable for welding.
5
The surfaces to be welded and the inside and outside
surfaces of the base metal shall be cleared of all
contamination for one inch back from the bevel before the
pipe is aligned and tack welded. Special cleaning methods
shall be used when specified in the Welding Procedure
Specification.
Remove grease, oil and cutting fluid using appropriate
solvents. After removing grease, oil or cutting fluid residue,
remove paint, varnish, rust, dirt or oxide using a wire brush
or grinding wheel. Paint which is designed to be welded over,
such as “Deoxaluminite” may be welded over without
removal. Brushing with a power wire brush to remove excess
build-up (i.e., runs) of weldable coatings is recommended.
When wire brushing stainless steel, use only austenitic
stainless steel wire brushes. Brushes for use on stainless
steel or other corrosion-resistant metals should be
segregated and not be used on carbon or low alloy steel.
These ordinary steel will contaminate the brush and result
in surface rusting of the corrosion-resistant metal if the
brush is used on corrosion-resistant metals.
The components being joined shall be aligned to provide the
root gap spacing given in the WPS. The inside surfaces shall
be aligned to within 1/16", or as shown in the WPS. When
the inside surfaces do not match within the required
tolerance, the surfaces shall be ground or weld metal shall
be added to bring the surfaces into alignment. When the
surfaces are ground or weld metal is added, the taper from
the original surface shall not exceed 30 maximum on
internal original surfaces and 3:1 (about 18) maximum on
external surfaces. The minimum wall thickness required by
engineering calculations shall be present after proper
6
alignment has been achieved. This may require the addition
of weld metal to outside pipe wall. It is recommended that
alignment be verified by using “Hi-Lo” gauges after has been
fit-up and tack welded.
When backing is shown as “Required” on the WPS, the
backing shall be backing ring or strip or other material
shown above, or it shall be weld metal deposited by another
process or electrode type for welds made from one side.
Welds which are made from both sides of a joint and fillet
welds are considered as welding “on backing,” in which case
the same process and electrode may be used on both sides.
Alignment shall be done using external alignment clamps or
by tack welding the ends. The use of welded lugs or
attachments and wedges to bring pipe into alignment is
permitted. If the base metal is alloy steel, the preheat
required by the WPS shall be used for tack welding and for
attachment of alignment materials. Lugs should be removed
by cutting and grinding followed by visually inspecting the
pipe surface for defects. Care should be taken not to grind
into the base metal when removing temporary welds
Tack welds, which will be incorporated into the final weld,
shall be tapered on both ends to facilitate proper fusion. Any
defective tack welds shall be removed by grinding. Tack
welds, which have been removed, shall be replaced if
necessary to maintain alignment or to prevent closing of the
root opening during root pass welding.
Fillet weld sizes, as shown on the Welding Procedure
Specification shall be used unless otherwise detailed on the
engineering drawing. Fillet welds shall be made so that they
penetrate fully into the root.
7
Electrodes and Filler Metals
Low hydrogen welding electrodes, such as E7015, E7018,
E8018, E9018 and E308-16 shall be purchased in vacuumsealed plastic wrappers or hermetically sealed containers.
After removal from the containers, these electrodes shall be
stored in holding ovens at 200 to 300F. Welders shall not
take more electrodes than can be consumed in the time
permitted as shown in Table 1 when using leather rod
pouches or other unheated containers. These electrodes are
not permitted to be stored in pockets of clothing, since they
will absorb body moisture. The use of portable holding ovens
is recommended. Electrodes that have been exposed to the
atmosphere for more time than permitted by Table 1 shall be
destroyed or baked at 700 ± 50F for 2-hour minimum.
TABLE 1
Low-Hydrogen Electrode Exposure Time Limits
Electrode Class
Exposure Time*
E7018
E8018
E9018, E502
E10018, E11018
E308-16
8 hours
4 hours
2 hours
2 hours
8 hours
* For electrodes designated as moisture resistant (e.g.,
E7018R), the exposure times may be doubled.
Note: In the above examples, the electrode classes E7018,
E8018, etc. are intended to include all other low-hydrogen
classes of electrodes, such as E7015, E7016, E8015, E9016,
etc. The electrode class E308-16 is intended to include all
8
E3XX-15 and E3XX-16 electrodes. The electrode E502 is
intended to include all E4XX, E5XX and E7Cr electrodes.
When portable heated rod containers are used, there is no
time limit provided the containers are kept hot.
Electrodes other than the low-hydrogen type shall be stored
in a dry place, sheltered from the elements, preferably at
normal room temperature and humidity. E6010 and E6011
electrodes shall never, ever be stored in heated holding
ovens.
The use of low-hydrogen welding electrodes is recommended
for all Shielded Metal Arc Welding (SMAW), except that the
use of EXX10 or EXX11 classification is recommended for
root passes in order to assure full penetration.
Preheating and Interpass Temperature
Preheating and interpass temperature shall be as indicated
in the Welding Procedure Specification. When higher
preheat is required by the applicable construction code (i.e.
B31.1, B31.9, etc.), that preheat shall be used for production
welding. Welding on metal that is wet is strictly prohibited;
wet metal shall be heated until it is at least warm to the
touch to assure removal of moisture.
The following additional preheat is recommended for P-1,
Group 2 materials (e.g, thick A-105 flanges):
9
TABLE 2
Recommended Supplemental Preheat
Thickness (in.)
Preheat (F)
Over 1/4 to 3/4
Over 3/4 to 1-1/4
Over 1-1/4 to 2-1/2
Over 2-1/2
150
200
250
300
Preheat and interpass temperature measurement shall be
made using temperature measuring crayons, contact
pyrometers or infrared thermometers. Preheat temperature
shall be measured on the base metal on the outside surface
of the pipe or on the beveled edge near the outside surface.
Interpass temperature shall be measured on the weld metal
or on the base metal near the weld metal prior to beginning
the subsequent weld bead pass. When using temperature
measuring crayons, any residual crayon shall be removed
before welding over the marked area.
Shielding and Backing Gas
When welding with a gas-shielded welding process, the area
in which welding is being done shall be protected from drafts
which can cause loss of the gas shield. Wind velocities in
excess of 5 mph are high enough for this to happen, resulting
in surface oxidation of the weld metal, oxide contamination
in the deposit, porosity, and loss of mechanical properties.
The use of tent-like enclosures is recommended in
unsheltered areas.
10
Proper gas coverage is indicated on most materials by a
silver or light gold color of the weld bead. After breaking the
arc, keep the torch over the weld bead long enough to
prevent it from oxidizing. Filler metal and tungsten should
also be kept under the protection of the inert gas until it has
cooled to well below the temperature at which it was
glowing. Purging of the hose and torch assembly is
recommended if the equipment has not been used for several
hours.
When sharpening a tungsten electrode by grinding, make a
small flat on the pointed end about 1/16" across. Final
grinding of tungsten electrodes should be done parallel to
the axis of the electrode so that the grinding marks go in the
direction of the point. Use of a diamond wheel is highly
recommended.
Purging shall be done using the purge gas specified in the
Welding Procedure Specification. The use of hard, removable
or inflatable type dams is recommended when the end of the
pipe is open so that the dam can be removed after making
the weld. The use of water soluble paper dams is
recommended for welds when removable dams cannot be
used. When backing flux is used, the acceptability of these
should be approved by the customer since the residual
material may contaminate the product stream.
Hard, removable purge dams can be made from wood,
hardboard or metal disks which are slightly smaller that the
pipe inside diameter. The edges of the disks should be
wrapped with a rubber gasket or foam material so the dam
is held in place by friction, yet is not so firmly held that is
difficult to remove. The dams should be far enough back
from the weld area so that the heat from welding does not
11
damage them. The dams should be connected to ropes or
wires that can be used to pull them out after welding is
complete. Do not remove dams until at least three weld
passes are complete, and the weld is cool enough to avoid
damaging the dam material. Purge dams are also
commercially available.
When using dams or when purging entire assemblies of pipe,
the welder should keep in mind that Argon is slightly
heavier than air, and that it will displace the air upward,
somewhat in the same manner as if the pipe were being
filled with water. The argon entry port should be located at
the physically lowest part of the piping, and the air
discharge port should be located at the physically highest
part of the piping.
The purge time may be established using Table 6 (page 25).
Alternatively, the displaced gas may be monitored using an
oxygen meter. Welding may begin when the oxygen level is
below 2% for stainless steel and 1% for nickel alloys. A flow
rate of 50 CFH is recommended for all purging until the
desired purge time or oxygen level is achieved. Once this is
complete, the purge gas flow rate should be reduced to
maintain a slight positive pressure inside the pipe while the
root pass and a few additional passes are being welded. This
practice will prevent the aspiration of oxygen into the inside
of the pipe by the shielding gas from the torch.
After the joint is aligned, including internal alignment and
root spacing, the groove(s) should be taped shut except that
an air discharge gap may be left open on the top of the pipe
when the pipe is in the horizontal position. Tack welds
should be made after purging is complete by peeling back 1
to 2 inches of tape, reducing the gas flow rate until there is a
12
slight gas flow outward from the opening, then making the
tack. Replace the tape after the tack is made. Repeat this
process at each location at which a tack is desired. After
tacking, turn the purge gas flow rate up, remove that tape
and grind, feather and inspect each tack, then replace the
tape, and reestablish the purge. Make the initial weld by
peeling back about 2 inches of tape on one side of a tack
weld, reduce the purge gas flow rate until there is a slight
outward flow, and begin welding. Peel the tape back no more
than a couple of inches at a time to be sure that the purge is
maintained and to preclude aspiration of air into the inside
of the pipe.
Tack welding of consumables inserts may be done without
first purging the pipe provided that very small tack welds
are made which do not fuse the internal portion of the insert.
Cleaning
Initial cleaning shall be performed using the methods
described in the Welding Procedure Specification. Surfaces
to be welded shall be free of grease, oil, paint, rust mill scale
and cutting oxides for at least 1/2 inch along the pipe from
the end preparation bevel.
Interpass cleaning shall be done using the methods
described in the Welding Procedure Specification. All slag,
silica deposits and other residual deposits from the welding
process on the surface of the weld and the surrounding base
metal shall be removed. The weld surface shall be inspected
and ground as necessary after each pass to be sure that the
contour of the weld is sound and that the geometry is
suitable for depositing the next layer of weld metal.
13
The completed weld shall be cleaned using the method
described in the Welding Procedure Specification for
interpass cleaning.
Environmental Requirements
Welding shall not be done when the air temperature is below
zero degrees F.
When welding with Gas Tungsten Arc Welding (GTAW), the
area in which welding is being done shall be protected from
drafts which can cause loss of the gas shield. Wind velocities
in excess of 5 mph are high enough to cause this to happen,
resulting in surface oxidation on the weld metal, oxide
contamination in the deposit, porosity, and loss of
mechanical properties. The use of tent-like enclosures is
recommended when welding outside or if there is wind.
When welding pipe which is vertical or near vertical, the
ends of the pipe should be capped off during welding to
prevent loss of shielding or backing gas due to the “chimney
effect.” When using SMAW, the welding area shall be
similarly protected when the wind velocity exceeds 20 MPH.
Welding Technique
The arc shall be struck on the face of the bevel or on
previously deposited weld metal, not on the external surface
of the pipe. When continuing the same bead around the pipe,
it is preferred that the arc be struck on metal about 3/8"
ahead of the previous bead then drawn back on to the
previous bead before continuing forward progress.
The welder shall visually inspect each weld bead for defects.
Any defects, including significant slag and porosity and all
14
cracks shall be removed by grinding or by carbon arc gouging
following by grinding.
Beads not more than 3/4 inches wide are permitted for any
welding process when the WPS permits weaving. When
stringer beads are required by the WPS, the weld shall be
made without significant motion of the electrode transverse
to the direction of travel.
Prior to depositing the next weld bead, any weld metal buildup which may have been left at any weld stop or re-start
locations shall be ground to blend uniformly with the
surrounding deposit and base metal contour.
Welding from Two Sides
When the inside surface of a weld is accessible, it shall be
visual examined by the welder for full fusion, adequate
penetration, convexity and concavity. Any defects shall be
removed by grinding to sound metal and welded from the
inside, if necessary, to bring the weld metal flush with the
surrounding base metal. On joints that are designed to be
welded from both sides, the root pass shall be ground or
carbon-arc gouged and ground to sound metal before
depositing weld metal from the inside surface
The inside surface of a production joint may be backgouged
using methods given in the Welding Procedure Specification
and welded from the inside of the pipe, as necessary. Before
welding the inside surface, that surface shall be visually
inspected for defects, and additional grinding shall be done
as needed to reach sound metal. When the WPS indicates
that backgouging is “none,” it means that the procedure is
not intended for use with backwelding; in these cases, use a
15
WPS which allows backwelding to make repairs from the
second side.
Visual Examination
The completed weld shall be cleaned using the methods
described in the Welding Procedure Specification for
interpass cleaning. The welder shall visually inspect the
finished weld surface for contour, reinforcement, undercut
and surface appearance as required by the applicable Code.
As-welded surfaces are permitted; however, the surface of
the welds shall be sufficiently free from coarse ripples,
grooves, overlaps, abrupt ridges, and valleys to avoid stress
risers. Undercuts shall not exceed 1/32 in. or 10% of the wall
thickness, whichever is less, and shall not encroach on the
required section thickness. The surfaces of the finished weld
shall be suitable to permit proper interpretation of
radiographic and other required nondestructive
examinations. If there is a question regarding the surface
condition of the weld, the nondestructive testing technician
shall determine whether or not the surface is suitable.
The weld metal for butt welds shall fill the groove until the
weld metal is at least flush with the surrounding base metal.
There is no minimum reinforcement required for groove
welds, although welders should aim for approximately 1/16
inch of reinforcement in order to avoid conflicts with
inspection personnel over adequacy of fill. Reinforcement
shall merge smoothly into the surrounding base metal, and
it shall not exceed the values given in Tables 3 and 4. Where
the root side of a weld is accessible, it shall also be
examined.
16
TABLE 3
ASME/ANSI B31.1 PIPING
Maximum Reinforcement (in.) at Design Temperature
Base Metal
Thickness
Over
750ºF
350/750ºF
Less Than
350ºF
Up to 3/16
1/16
1/8
3/16
Over 3/16-1/2
1/16
5/32
3/16
Over ½-1
3/32
3/16
3/16
Over 1
1/8
1/4
1/4
TABLE 4
ASME/ANSI B31.3 PIPING
Maximum Reinforcement Limits
Base Metal
Thickness (in)
Maximum
Reinforcement (in)
1/4 and thinner
1/16
Over 1/4 to 1/2
1/8
Over ½ to 1
5/32
Over 1
3/16
Concavity on the root side of a single welded circumferential
butt weld is permitted when the resulting thickness of the
weld is at least equal to the thickness of the thinner member
of the two sections being joined and the contour of the
concavity is smooth without sharp edges. The following
17
indications on surfaces that are accessible for visual
examination are unacceptable:

Cracks

Lack of fusion

Incomplete penetration when inside surface is readily
accessible. (Note: For B31.3 Normal Fluid Service (i.e.,
where random radiography is required) and all B31.9
work, incomplete penetration up to 1-1/2 inches long in
any 6 inches of weld length is acceptable.)

Surface porosity having dimensions greater than 1/8 in.
(5.0 mm) or four or more rounded indications of any size
separated by 1/16 in. (2.0 mm) or less edge to edge in
any direction.
Repairs
Defects found during inspections shall be removed as
required to satisfy weld quality requirements. After defect
removal, the section to be repaired shall be arc gouged
and/or ground to make the repair cavity adequately open to
allow easy access with the electrode to the bottom of the
cavity. The surface to be welded shall be clean and smooth to
ensure fusion. Repair welds may be made using the same
WPS as was used to make the original weld or any other
WPS appropriate for the combination of base metals, heat
treatment, thickness, etc. to be welded. The repair cavity
and surrounding base metal shall be preheated as required
by the WPS or the governing code. When the base metal is a
corrosion resistant alloy such as stainless steel, a backing
gas should be used if the remaining base metal is less than
18
3/16" thick and when backing gas is required for the original
construction.
Stamping of Welds
Each welder shall apply his identification at each weld using
a steel die stamp. He shall stamp the base metal within one
inch of the edge (toe) of the weld or on a flat spot ground on
the weld metal. The welder may, when so directed, record
his stamp number on permanent documentation at the
reference to the weld(s) that he made, or he may mark the
weld with appropriate identification using a vibratory
etcher. Use of a permanent marker is acceptable for pipe
that is less than 1/4 inch thick.
Safety
To ensure a safe workplace the welder or welding operator
shall read and understand the safety policies of his
employer. There are also certain inherent dangers that the
welder needs to always keep in mind when engaged in
welding operations. These can be reduced through safe work
procedures and practices, some of which are listed below:
1.
Keep your head out of the smoke plume when welding.
2.
Wear proper eye and face protection (welding helmets,
safety glasses with side shields, or goggles) with correct
filter plates/lenses to avoid flash burns and to keep
objects from hitting the eye. Make certain that others
working around welding are adequately protected.
3.
Wear flame resistant clothing, gauntlets and aprons to
protect arms from heat, radiation and sparks. Avoid
19
pant cuffs or folds where hot metal can lodge while
welding.
4.
Make sure there is adequate ventilation to keep fumes
from your breathing area. Before striking the arc, make
sure area is free of dust, flammable liquid and fumes
that could ignite or cause an explosion.
5.
Do not enter confined spaces without first checking that
there is sufficient good quality air available inside the
confined space. Make sure continuous ventilation is
provided when welding or cutting in confined spaces.
Never use oxygen for ventilation.
6.
Maintain welding equipment in a condition that
prevents fire and electric shock.
For additional safety pointers read the MCAA publication
“Safety Manual for the Mechanical Trades.”
Welding Hazards
The OSHA Hazard Communication Standard requires that
all workers be provided information on workplace hazards,
and how, through proper work practices, exposure to these
hazards can be reduced or minimized. Similar requirements
may be enforced by state agencies.
During the welding process certain gases and fumes are
generated which could be dangerous to your health. Before
the start of welding read the warning labels on material
containers to find out what hazards are associated with the
use of the material.
20
Know the base metals being welded and know the type of
hazardous fumes that may be created when the metal is
heated to welding temperatures.
If you need more information on the material than is
provided on the container label ask your supervisor to go
over the “Material Safety Data Sheet” (MSDS) with you.
Welding Lens Shades
The following welding shades are recommended:
TABLE 5
Welding Lens Shade Selections
Application
Gas Cutting up to 1 inch thick
Gas Cutting over 1 inch thick
SMAW up to 5/32 inch electrodes
SMAW over 5/32 inch electrodes
GMAW or FCAW up to 250 amps
GMAW or FCAW over 250 amps
GTAW
Carbon Arc up to 250 amps
Carbon Arc over 250 amps
Plasma Cutting up to 300 amp
Plasma Cutting over 300 amps
21
Shade
Number
3 or 4
4 or 5
10
12
11
12
12
12
14
9
12
TABLE 6
Determining Purge Time
This table calculates time for various pipe or tube sizes
based on the flow rate and volume changes specified
Use of pipe diameter as either NPS or OD is inconsequential
and does not affect the efficacy of the calculations
Volume Changes: 5
Flow Rate CFH:
50
Purge Time (Minutes
Pipe Diameter or
Per Foot of Pipe
Size
Length)
3
0.3
3-1/2
0.4
4
0.5
4-1/2
0.7
5
0.8
6
1.2
8
2.1
10
3.3
12
4.7
14
6.4
16
8.4
18
10.6
20
13.1
24
18.8
30
29.4
36
42.4
48
75.4
Basis: seconds will it take to purge 1 foot of pipe 5 volume
changes
sec/ft = 5 X  X radius2 (in2 ) X (ft3 /1728 in3 ) X (3600 s/hr) X
(hr/50ft3 ) X 12 in/ft
22
To calculate the prepurge time for any length of pipe,
multiply the value obtained from the Table by the length of
pipe measured in feet.
Example: Find time required for prepurging of 200 ft. of NPS
5. pipe. From Table for NPS 5 pipe size, the purge time is .8
min. per 1 ft. of pipe, hence, 200 ft. x .8 = 160 minutes or 2
hours, 40 minutes.
Caution: Inert gases displace air and settle in low places.
They can cause death by oxygen deprivation.
23
ASME P-Numbers
The ASME P-number system groups metals according to
comparable characteristics such as composition, weldability
and mechanical properties. The reason for grouping base
metals in this manner is to reduce the number of welding
procedure and welder performance qualifications that would
otherwise be required. The following is a listing of piping
and pressure vessel materials by base metal P-number.
Materials that are not listed here can be found in QW/QB422 of ASME Section IX and in the allowable stress tables of
the B31 Code Sections.
Carbon Steel and Alloys
P
Spec. Type or
No. Numbers Grade Product Type
1
A-36
Structural Shapes, Plate
A-53 All
Seamless and Welded Pipe
A-105
Forgings
A-106 A,B,C
Seamless Pipe
A-108 1015,1018, Bars, Tube
A-181 C1.60,70
Pipe, Flanges
A-216 WCA,B,C
Castings
A-234 WPB, WBC Pipe Fittings
A-285 All
Plate
A-333 1,6
Seamless and Welded Pipe
A-334 1,6
Seamless and Welded Pipe
A-350 LF1,2
Forgings
A-352 LCA, B
Castings
A-420 WPL
Forgings
A-515 All
Plate
A-516 All
Plate
24
A-519
A-671
A-672
API-5L
1018, 1020
CA,CB,CC
A,B,C,E
All
Bar, Tube
Fusion Welded Pipe
Fusion Welded Pipe
Seamless and Welded Pipe
Carbon Molybdenum Steel and Alloys
P
Spec. Type or
No. Numbers Grade Product Type
3
A-209
A-213
A-387
A-691
All
T2
Gr.2
CM65/76
Seamless Tube
Seamless Tube
Plate
Fusion Welded Pipe
Chromium molybdenum Steel and Alloys
P
Spec. Type or
No. Numbers Grade Product Type
4
A-182
A-213
A-234
A-335
A-387
A-691
F11,12
T11
WP11
P11,12
Gr.11,12
1-1/4CR
Pipe Flanges, Forgings
Seamless Tube
Pipe Fittings
Seamless Pipe
Plate
Fusion Welded Pipe
25
Chromium Molybdenum Steel and Alloys
P
Spec. Type or
No. Numbers Grade Product Type
5A
A-182
A-213
A-234
A-335
A-387
A-691
F21,22
T22
WP22
P21,22
Gr.21,22
2-1/4Cr.
Pipe Flanges, Forgings
Seamless Tube
Pipe Fittings
Seamless Pipe
Plate
Fusion Welded Pipe
P
Spec. Type or
No. Numbers Grade Product Type
5B
A-182
A-213
A217
A-234
A-335
A-387
A-691
F5,7,9,91
T5,7,9.91
C12A
WP5,7,9,19
P-5,7,9,91
Gr. 5,7,9,91
5,7,9 Cr.
Pipe Flanges, Forgings
Seamless Tube
Casting
Pipe Fittings
Seamless Pipe
Plate
Fusion Welded Pipe
26
Steels Alloyed with Nickel
P
Spec. Type or
No. Numbers Grade Product Type
9A
A-182 FR
Pipe Flanges, Forgings
A-203 A,B
Plate
A-234 WPR
Pipe Fittings
A-333 7,9
Seamless Pipe
A-334 7,9
Welded Pipe and Tube
A-350 LF2, 5, 9
Forging
A-352 LC2
Castings
A420 WPL9
Fittings
A-714 V (Yolloy) Seamless and Welded Pipe
P
Spec. Type or
No. Numbers Grade Product Type
9B
A-203 D,E,F
Plate
A-333 3
Seamless Pipe
A-334 3
Welded Pipe and Tube
A-350 LF3
Forging
A-352 LC3
Castings
A420 WPL3
Fittings
27
Stainless Steel and Alloys
P
Spec. Type or
No. Numbers Grade Product Type
8
A-182 F3XX
Pipe Flanges, Forgings
A-213 TP3XX
Seamless Tube
A-240 Type3XX
Plate
A-312 TP3XX
Seamless or Welded Pipe
A-403 WP 3XX
Pipe Fittings
10H A-182 F50,51
Pipe Flanges, Forgings
A-789 All
Seamless and Welded Tube
A-790 All
Seamless and Welded Tube
Creep-strength Enhanced Ferritic Steel
P
Spec. Type or
No. Numbers Grade Product Type
15E A-182 F91, F92
Pipe Flanges, Forgings
A-213 TP91, TP92 Seamless Tube
A-217 C12A
Casting
A-234 WP91, 92
Pipe Fittings
A-335 P-91, P-92 Seamless Pipe
A-336 F91
Forging
A-369 FP91, FP92 Forged Pipe
A-387 Gr 91, Cl 2 Plate
A-691 Gr 91
Fusion Welded Pipe
28
Aluminum and Aluminum Base Alloys
P
Spec. Type or
No. Numbers Grade Product Type
21
B-209 1100,3003 Sheet, Plate
B-210 1100,3003 Tube
B-211 1100,3003 Bar, Rod, Shapes, Pipe, Tube
B-221 1100,3003 Bar, Rod, Shapes, Tube
B-234 1100,3003 Seamless Tube
B-241 1100,3003 Seamless Pipe, Extruded Tube
23
B-209 6061,6063 Sheet, Plate
B-210 6061,6063 Tube
B-211 6061,6063 Bar, Rod, Shapes, Pipe, Tube
B-221 6061,6063 Bar, Rod, Shapes, Tube
B-234 6061,6063 Seamless Pipe, Extruded Tube
B-241 6061,6063 Seamless Pipe, Extruded Pipe
B-247 6061
Forgings
Copper and Copper Base Alloys
P
Spec. Type or
No. Numbers Grade Product Type
31
B-111 All
Seamless Pipe
32
B-111 Brass
Seamless Pipe
B-171 C44300
Seamless Pipe
B-359 C44300
Seamless Pipe
34
B-111 Cu-Ni
Seamless Pipe
29
Nickel and Nickel Base Alloys
P
Spec. Type or
No. Numbers Grade Product Type
41
B-161 N02200,1 Pipe, Tube
42
B-165 N04400 Seamless Pipe and Tube
Monel 1
43
B-163 N06600 Seamless Pipe and Tube
Inconel 600
B-167 N06690 Seamless Pipe and Tube
Inconel 690
B-443 N06625 Seamless Pipe and Tube
Inconel 625
B-516 N06600 Seamless Pipe and Tube
B-517 N06600 Seamless Pipe and Tube
B-564 N06600 Seamless Pipe and Tube
B-564 N06625 Seamless Pipe and Tube
B-564 N10276 Forgings, Smls and Welded Pipe
Hastelloy 276
B-619 N06022 Forgings, Smls and Welded Pipe
Hastelloy 22
45
B-163 N08020 Seamless and Welded Pipe
Alloy 20
SB-407 N08800 Seamless Pipe and Tube
Incoloy 800
B-423 Alloy 825 Seamless and Welded Pipe
Incoloy 825
B-462 N08020 Forgings
Alloy 20
B-463 N08020 Forgings, Smls and Welded Pipe
B-464 N08020 Seamless and Welded Pipe
1
Trade name is listed below Type/Grade the first time it appears.
30
B-464
B-464
B-468
B-468
NO 8020
N08026
N08020
N08026
Forgings, Smls and Welded Pipe
Forgings, Smls and Welded Pipe
Forgings, Smls and Welded Pipe
Forgings, Smls and Welded Pipe
Titanium and Titanium Base Alloys
P
Spec. Type or
No. Numbers Grade
51
B-337
1,2,7
B-338
1,2,7
B-363 WPT1,2
52
B-337
3,12
B-338
3,12
B-363
WPT3
Product Type
Seamless and Welded Pipe
Seamless and Welded Tube
Seamless and Welded Fittings
Seamless and Welded Pipe
Seamless and Welded Tube
Seamless and Welded Fittings
31
Item PW4
National Certified Pipe Welding Bureau
1385 Piccard Drive • Rockville, MD 20850–4340
301–869–5800 • 301–990–9690 • www.mcaa.org/ncpwb
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