gb50236-98 welding code for construction and inspection of field equipment and industrial piping

7/24/2019 GB50236-98 Welding Code for Construction and Inspection of Field Equipment and Industrial Piping

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GB 50236-98

Welding Code

For Construction and Inspection ofField Equipment and Industrial Piping

Issue Date: Dec. 11, 1998 Implementation Date: Jun. 01, 1999

Issued by State Bureau of Quality and Technical Supervision and Ministry of

Construction of P.R.C


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National Standard of P.R.C

Welding Code For Construction and Inspection of Field Equipment and Industrial Piping

GB 50236-98

Written by: Former Ministry of Chemical Industry of P.R.C

Approved by: Ministry of Construction of P.R.C

Implementation Date: Jun. 1, 1999

China Plan Publishing House

1998 Beijing


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Notice About Issuing National Standard Welding Code For Construction and

Inspection of Field Equipment and Industrial Piping

Construction Standard [1998] No. 253

According to the requirements of the [1991] No.290 file of State Technology Committee, the Welding Code

For Construction and Inspection of Field Equipment and Industrial Piping revised by the former ministry of

chemical industry and relevant departments passed joint examination of relevant departments. Now the

Welding Code For Construction and Inspection of Field Equipment and Industrial Piping GB50236-98 is

approved as mandatory standard, and is implemented on Jun.1, 1999. The former Welding Code For

Construction and Inspection of Field Equipment and Industrial Piping (GBJ 236-82) is annulled

correspondingly.

State Bureau of Petroleum and Chemical Industry is responsible for administering this code, National

Administration Center for Chemical Construction Standardization is responsible for works such as specificexplanation etc., and the Standard Rating Research Institute of the Ministry of Construction is responsible for

its publication and issue.

Ministry of Construction of P.R.C

Dec. 11, 1998


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Contents

1. General Principals ( 1)

2. General Regulations ( 2)

3. Materials ( 4)

4. Welding Procedure Qualification ( 6)

4.1 General Regulations ( 6)

4.2 Qualification Rules ( 6)

4.3 Test and Qualification (13)

5. Examination of Welders (22)

5.1 General Regulations (22)

5.2 Content And Method of Operation Skills Exam (24)

5.3 Test Piece Assessment (33)

6. Welding of Carbon Steel And Alloys Steel (35)


6.2 Preparations Before Welding (36)

6.3 Welding Procedure Requirements (38)

6.4 Pre-Heating Before Welding And Heat Treatment After Welding (40)

7. Welding of Aluminum And Aluminum Alloys (43)


7.2 Preparation Before Welding (43)


8. Welding of Copper And Copper Alloys (48)




9. Welding of Commercial Pure Titanium (52)

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10. Welding of Nickel And Nickel Alloys (55)




11. Welding Inspection (58)

11.1 Inspection Before Welding (58)

11.2 Inspection In Welding (59)

11.3 Inspection After Welding (59)

11.4 Welding Engineering Hand Over Acceptance (66)

Annex A The Format of Welding Procedure Qualification Record And Welding Guide Book (67)

Annex B The Format of Welder Exam Record, Registration Shape of The Welder Exam Result

And Welder Qualification Certificate (72)

Annex C The Type and size of the bevel of Weldment (76)

Annex D Selection of Welding Materials (88)

Annex E Radiographic Test of Aluminum And Aluminum Alloys Weld (97)

Annex F Radiographic Test of Commercial Pure Titanium (102)

Annex G Wording Explanation of This Standard (104)

Additional Explanation (105)

Attachment: Article Explanation (107)

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1 General Regulations

1.0.1This code is established to guarantee the quality of welding engineering of constructional field equipment

and industrial metal pipe.

1.0.2 This code applies to the construction and inspection of the welding engineering for the covered arc

welding, argon arc welding, carbon dioxide welding, submerged arc welding and oxyacetylene welding of

carbon steel, alloys steel, aluminum and aluminum alloys, copper and copper alloys, commercial pure titanium,

nickel and nickel alloys.

1.0.3 This code does not apply to the welding engineering of construction field joint welded boiler and pressure

vessel.

1.0.4 The safety control and labor protection of the welding engineering should be carried out according to

relevant regulations of current national guidelines, policies, laws and codes.

1.0.5 Besides this code, the construction of welding engineering has to execute the regulations of current

national standards and codes.

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2 General Regulations

2.0.1 The parent metal, welding material, weld joint factor and the shape of weld bevel should be indicated in

the design documents, and requirements to welding method, pre-heating before welding, heat treatment after

welding and welding inspection should be brought up in it.

2.0.2 Welding personnel and their responsibilities should meet the following regulations:

2.0.2.1 The welding technician position should be assumed by people with technical secondary school degree

or above and a certain welding experiences.

The welding technician is responsible for evaluating welding procedure, establishing welding guide book and

welding technique measures, participating in welding quality management, dealing with welding technique

problems and sorting welding technique data.

2.0.2.2 The welding quality inspector position should be assumed by people with technical secondary school

degree or above or equivalent and a certain welding experiences and skills.

The welding quality inspector is responsible for executing complete inspection and control to field welding,

identifying welding test position, evaluating welding quality, signing inspection document and participating in

the authorization of welding technique measures.

2.0.2.3 The nondestructive detection personnel position should be assumed by people who have qualified in the

examination of national authorized professional examination organization. They will undertake welding

detection and audit work according to their qualification items in the examination and authority.

The nondestructive detection personnel should inspect the position identified by the quality inspectors, evaluate

weld quality, sign and issue inspection document and refuse to inspect weld that does not meet the appearance

inspection requirements.

2.0.2.4 The welder must take examination according to the 5 chapter in this code and begin to work after

qualified in the examination.

The welder should weld following the welding guide book and welding technique measures. When facing

operating condition that does not meet the requirements in welding guide book and welding technique measures,

the welder should refuse to weld.

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2.0.2.5 The welding heating treatment personnel should take professional training..

The welding heating treatment personnel should do the heat treatment work of weld according to the relevant

regulations in the code, welding guide book and design documents.

2.0.3The construction unit should be qualified in the following conditions:

2.03.1 The construction unit should establish welding quality management system, and the welding technicians,

welding quality inspectors, nondestructive detection personnel, welder and welding heating treatment personnel

should be available.

2.0.3.2 The welding tooling, inspection methods should meet the specification of corresponding welding

engineering.

2.0.3.3Before the welder examination and welding starts, the construction unit should have welding procedure

qualification of corresponding program.

2.0.4 The welding environment should meet the following requirements

2.0.4.1 The welding temperature should be able to ensure that the welding temperature and welder skills are not

affected.

2.0.4.2 The wind speed should not exceed the following requirements when welding. If it exceeds the

requirements, wind proofing measures should be taken.

(1) Covered arc welding, submerged arc welding and oxyacetylene welding: 8m/s.

(2) Argon arc welding, carbon dioxide welding: 2m/s.

2.0.4.3 The relative humidity within 1m of the welding arc should meet the following requirements:

(1) Welding of aluminum and aluminum alloyss: No more than 80%

(2) Welding of other materials: No more than 90%

2.0.4.4 When the surface of the weldment is wet or covered with ice and snow, or when it rains, snows and

blows, and protective measures are not taken to protect the welder and the weldment, welding should not be

carried out.

2.0.5 For rework of disqualified weld, quality analysis should be taken before rework. When over twice

reworks are taken to a same position, rework measures must be worked out, which are to be approved by

technique principal before rework. Repairing welding procedure should be the same to original welding

procedure, and should comply with the regulations in 4.2.10.

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3 Material

3.0.1 The materials used in welding engineering should comply with the regulations in design documents.

3.0.2 The materials must have quality certificate of the manufacturer, and their quality should not below the

regulation in current national standard.

3.0.3 Before the materials are used, inspection and acceptance must be made to them according to regulations

of relevant current national standard. For new material designed, the design unit should provide the weldability

data of it.

3.0.4 The welding rod should comply with current national standards Carbons Steel Welding Rod GB5117,

Low Alloys Steel Welding Rod JB2385, Stainless Steel Welding Rod GB983, Build up Welding Rod

GB984, Aluminum and Aluminum Alloys Welding Rod GB3669, Copper and Copper Alloys Welding Rod

GB3670 and Nickel and Nickel Alloys Welding Rod GB/T13814.

3.0.5 The welding wire should comply with current national standards Steel Wire for Welding GB1300,

Stainless Steel Wire for Welding GB4242, Aluminum and Aluminum Alloys Welding Wire GB10858,

Copper and Copper Alloys Welding Wire GB9460, Titanium and Titanium Alloys Welding Wire GB3623,

Superalloys Cold-drawn Wire for Welding GBn8110 and Welding Wire for Carbon Dioxide Welding

GB8110.

3.0.6 The warehouse and drying and decontaminating equipment for the welding materials in construction field

should comply with the current national standard Management Regulations for the Quality of Welding Rod

JB3223, and storage, drying, cleaning and delivering system should be established.

3.0.7 The welding flux for submerged arc welding should comply with current national standard Carbon Steel

Submerged Arc Welding FluxGB5293 and Welding Flux for Low Alloys Steel Submerged Arc Welding

GB1270.

3.0.8 The argon gas used for argon arc welding should comply with current national standard Argon Gas GB

4842 with the purity no less than 99.96%.

3.0.9 For manual argon-shielded tungsten arc welding, cerium tungsten electrode or thorium tungsten electrode

is preferred.

3.0.10 The purity of the carbon dioxide used for carbon dioxide welding should not be less than 99.5% with

water content no more than 0.0005%. Pre-heating and drying are necessary before it is used. When the air

pressure in the cylinder is less than 0.98MPa, using should be stopped.

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3.0.11 The purity of the oxygen used for oxyacetylene welding should not be less than 98.5, and the purity of

the acetylene gas and the remaining pressure in the gas cylinder should comply with current national standard

Dissolved Acetylene GB6819. When calcium carbide is used to produce acetylene gas, the quality of the

calcium carbide could be determined by checking the sulfur and phosphorus content in the weld, and the sulfur

and phosphorus content must not exceed the standard value of the parent material.

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4 Welding Procedure Qualification

4.1 General Regulations

4.1.1 After the weldability of the material is confirmed, welding procedure qualification should be made to the

material to be welded before welding.

4.1.2 The material used for welding procedure qualification should comply with the regulations in the 3 chapter

of the code.

4.1.3 Procedure measures of the welding procedure qualification sample (herein after referred as qualification

sample) such as bevel processing, grouping and cleaning etc. should comply with relevant regulations of this

code.

4.1.4 The qualification sample should be welded by skilled welder.

4.1.5 Record should be made during welding procedure qualification process, and after the qualification is

completed, welding procedure qualification report should be given and should be reviewed and approved by the

welding technique principal. The format of the welding procedure qualification report should comply with the

regulations in sub-clause A.0.1 in attachment A.

4.1.6 Before welding, welding guide book worked out based on welding procedure qualification report. A

welding guide book can be worked out based on one or several welding procedure qualification reports, and

one welding procedure report can be used to make several welding guide books.

The format of the welding guide book should comply with the regulations in sub-clause A.0.2 in attachment A.

4.1.7 When the regulations in sub-clause 2.0.3 of this code is meet, for the different construction units within

the same quality management system, welding procedure qualification does not have to be made repeatedly to

the same procedure.

4.2 Qualification Rules

4.2.1 Bevel butt welds sample is used in welding procedure qualification. Welding procedures that qualified in

bevel butt welds sample qualification can also be used in fillet welds.

4.2.2 Pipe sample or plate sample should be used as qualification sample. Welding procedures that qualified in

plate sample qualification can be used for pipe weldment, and welding procedures that qualified in pipe sample

qualification can be used for plate weldment.

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4.2.3 The parent metals should be classified and grouped according to their chemical composition, mechanical

properties and welding properties as shown in table 4.2.3. Separate welding procedure qualification should be

made to parent metals that cannot be classified and grouped according to table 4.2.3.

Parent Metal Assortment and Grouping Table Table 4.2.3

Category No. Group No. Parent Metal Category Examples

P1 1-1 Carbon Steel with carbon content 0.3%Q235-AF,Q235-A,B,C

20R,20G,20HP,10,20,25

2A-1Low alloys structural steel with tensile

strength low limit less than 480MPa


strength low limit 480~550MPa

16Mn,16MnR,16MnRc,

15MnV,15MnVR,15MnVRCP2A


strength low limit 550~620MPa

15MnVNR,18MnMoNbR

2B-1

Alloys steel for use in low temperature,

with the lower limit of using temperature

-40

16MnDR

2B-2



-70

09Mn2VD,09Mn2VDRP2B

2B-3



-90

P3 3-1

Refractory steel

C-Mo

0.5Cr-0.5Mo 12CrMo

P4 4-1

Refractory steel

1Cr-0.5Mo

1.25Cr-0.5Mo

1Cr-0.5Mo-V

15CrMo

12Cr1MoV

P5A 5A-1

Refractory steel

2.25Cr-0.5Mo

2Cr-0.5Mo

12Cr2Mo


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Table 4.2.3 continued


P5B 5B-1Refractory steel

0.5Cr-1Mo 1Cr5Mo

P6 6-1 Martensitic stainless steel 1Cr13

P7 7-1 Ferritic stainless steel 0Cr13

8-1

Austenitic stainless steel

18Cr-8Ni

18Cr-12Ni-2Mo

18Cr-13Ni-3Mo

0Cr19Ni9, 0Cr18Ni9Ti,

0Cr18Ni11Ti, 00Cr18Ni10,

00Cr19Ni11,

0Cr18Ni12Mo2Ti,00Cr17Ni14Mo2,

0Cr18Ni12Mo3Ti,00Cr19Ni13Mo3,

0Cr19Ni13Mo3

P8

8-2


25Cr-13Ni

25Cr-20Ni

0Cr23Ni13

0Cr25Ni20

P9A

Nickel alloys steel for use in low

temperature, with nickel content less than

2.5%

P9B


temperature, with nickel content

2.5~3.5%

P11


temperature, with nickel content 9%

P21Aluminum and aluminum-manganese

alloys

L1, L2, L3, L4, L5, L6, LF21

P22Aluminum-magnesium alloys with

magnesium content less than 4%

LF2, LF3

P25Aluminum-magnesium alloys with

magnesium content more than 4%

LF4, LF5, LF6, LF11

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P31 Red copper T1, T2, T3, TP1, TP2

P32 Brass H62, H68,Hfe59-1-1

P41 Nickel 99.0Ni series

P42 Nickel alloys Ni-Cr series

P43 Nickel alloys Ni-Cr-Fe series GH3030, GH3039

P45 Nickel alloys Ni-Fe-Cr series GB1140

P51 Titanium TA1, TA2, TA3

4.2.4 When the welding method is changed, welding procedure qualification should be made again.

4.2.5 When several welding methods are used in a same welding joint, welding procedure qualification can be

made for each kind of welding method, or make integrated welding procedure qualification, and after integrated

welding procedure qualified, each welding method can be applied to the weldment separately, however, the

thickness of the weld metal should comply with the regulations in sub-clause 4.2.9 of this code.

4.2.6 Welding procedure factor includes major factor, added major factor and minor factor. Major factor refers

to the welding procedure factors that can affect the tensile strength and bending property of the welding joints;

added major factor refers to the welding procedure factors that can affect the impact property of the welding

joints; minor factor refers to the welding procedure factors that have no significant effect on the measured

mechanical properties.

When any of the major factors is changed, welding procedure qualification must be made again; if impact

property is required in design, when adding or changing any of the added major factors, impact property

samples should be welded to test according to the added or changed added major factors; when changing minor

factors, welding procedure qualification does not have to be made again, but welding guide book must be

re-worked out.

The major factors and added major factors of the welding procedure qualification are determined according to

table 4.2.6.

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Major factors and added major factors

Major factors

Category Welding Condition

Oxyacetylene

welding

Manualarcwelding

Submerged

arc

welding

Consumable

electrodeargonarc

welding

Carbon

dioxide

welding

Argon-shielded

tungsten

arc

welding

Oxyacetylene

welding

Manualarcwelding

1. Welding rod designation (except the third

number in the designation of steel welding rod)

2. When only the third number in the designation

of steel welding rod is changed, use non-hydrogen

coated welding rod to take stead of low hydrogen

coated welding rod.

3. The diameter of the welding rod is changed to

more than 6mm.

4. Steel grade of the welding wire

5. Welding flux designation; the mixing ratio of

the mixed welding flux.

6. Add or cancel the additional filling metal: the

additional filling metal amount

7. Change virtually-cored wire to flux-cored wire,

or the opposite.

8. Add or cancel the initial filling metal: the

chemical composition range of the initial filling

metal

Fillingmaterial

9. Add or cancel filling metal

Welding

Position

Change the welding in the position qualified to

upward vertical welding.

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Major factors and added major factors


Major factors Added major factors

Welding Condition

Oxyacetylene

welding

Manual

arc

welding

Submergedarc

welding

Consumable

electrodeargon

arcwelding

Carbondioxide

weldin

Argon-shielded

tungsten

arc

welding

Oxyacetylene

weldin

Manual

arc

welding

Submergedarc

welding

Consumable

electrodeargon

arcwelding

Carbondioxide

. The pre-heating temperature is 50 lower

han the qualified value.

2. The highest interlayer temperature is 50

higher than the qualified value.

. The proportion of the mixing protective gas

2. Change the single protective gas to mixingprotective gas, or cancel the protective gas.

. Kind or polarity of the current

2.Increase line energy or the unit deposit metal

volume exceeds the qualified value (If the heat

reatment after welding has thinned the crystal

grain, line energy or deposit metal volume does

not have to be measured.)

. The amplitude and frequency of the swing of

he welding wire and retention time at both sides

2. Change single pass welding on each face to

multi pass welding, on each face or the opposite.

3. Change single welding wire to multi welding

wire.

4. The amplitude and frequency of the swing of

he electrode (tungsten electrode) and retention

ime at both sides

Note: Items marked with are major factors or added major factors of that welding method.

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4.2.7 The recognition scope of the parent metals used in the qualified welding procedure should comply with

the regulations in table 4.2.7.

The Recognition Scope of The Parent Metals Used In The Qualified Welding Procedure Table 4.2.7

The Parent Metals of the qualification sample Recognition scope

One category number + the same category

number

Form welding joint with the same qualification test piece of the

same category number.

One category number + another category

number

Form welding joint with the same qualification test piece of

two category numbers.

P3+P3 P3 forms welding joint with P3, P2A, P2B or P1.

P4+P4 P4 forms welding joint with P4, P3, P2A, P2B or P1.

P5A+P5A P5 forms welding joint with P5A, P4, P3, P2A, P2B or P1.

P5A, P4 or P3 + another lower category

number

P5A, P4 or P3 form welding joint with lower category number

Form welding joint with the same qualification test piece of the

same category number or P1

Form welding joint with the same qualification test piece of

two category numbers.

P(2A-2) forms welding joint with P(2A-2) or P(2A-1)

In P2A category number:

One category number + the same category

number

One category number + another category

number

P(2A-2)+P(2A-2)

P(2A-3)+P(2A-3)

P(2A-3) forms welding joint with P(2A-2), P(2A-2) or P(2A-1)

Note: + in the table means to weld with.

4.2.8 When changing heat treatment kind after welding, welding procedure qualification should be made again.

4.2.9 The recognition scope of the thickness of the parent metals and of the weld metal used in the qualified

welding procedure should comply with the regulations in table 4.2.9.

Recognition Scope Of The Parent Metals Used In The Qualified Welding Procedure Table 4.2.9

The recognition scope for the thickness

of the Parent Metal of the weldment

The recognition scope for the

thickness of wedd metal

The thickness of the Parent Metal

of the qualification test piece(T)Max. Min. Max.

1.5T


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thickness of the Parent Metal for weld rewelding that applied in the qualified welding procedure is not limited.

4.2.11 Qualified welding procedure can be applied in butt weldment with unequal thickness, however the

thickness of the Parent Metal at the both sides of the weldment should be within the recognition scope.

4.2.12 When the qualified welding procedure is applied in fillet weld, the thickness of the parent metals for

fillet weld are not limited.

4.3 Test and Qualification

4.3.1 The inspection and test items of the qualification test piece should be appearance inspection, radiographic

test and mechanical test.

4.3.2 In appearance inspection and radiographic test, the weld quality should not be lower than the class

standard in table 11.3.2 of this code.

4.3.3 The mechanical test to qualification test piece with heat treatment requirements should be made after heat

treatment.

4.3.4 Mechanical test should be tensile test and bending test, whose sample kind and number should comply

with the regulations in table 4.3.4. For parent metals without requirements to bending property, such as casting

bend pipe, bending test does not have to be made to its test piece.

Kind And Amount of The Sample Used In Tensile And Bending Test Table

4.3.4

Kind And Amount of The Sample (Piece)

Tensile Test Bending Test

The Thickness of The

Parent Metal of

Qualification Test Piece T

(mm)Tensile Sample

Face Bending

Sample

Back Bending

Sample

Side Bending

Sample

1.5T


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4.3.5 When impact test is required to be made according to the design documents and relevant standards, select

three impact samples separately at the weld and the heat affected zone; for weld with different parent metals at

both sides, select three impact sample at each side of the heat affect zone.

4.3.6 For sampling of test piece, machine cutting is preferred. Conduct cold aligning before cutting. When

flame cutting is adopted for sampling, machining allowance should be reserved. The sequence and position of

sampling should comply with the regulations in Fig. 4.3.6-1 and Fig. 4.3.6- 2

(c) When sampling vertical bending sample

Fig. 4.3.6-1 Sampling Position of Plate Test Piece

14

discard

Backup

Re ect Re ect

Tensile sample

Back bending

Face bending

Use

Tensile

Impact

discard

Impact

discard

Backup Use

Tensile

Side bending

Re ectRe ect

sample

sample

sample

sample

sample

sample

sample

sample

sample

sample

sample

sample

sample

Back bending

Face bending Side bending

Side bending

Side bending

Tensile

(a) When side bending sample sampling is not needed (b) When sampling side bending sample

Vertical

face

bending

Vertical

back

bending

Vertical

face

bending

Vertical

back

bending

Reject

Reject

sam

le

sam

le

sam

le

Tensile

Tensile

Im

ac

discard


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(c) When impact test is required

Fig. 4..3.6-2 The Sampling Position of Pipe Test Piece

1Tensile sample 2Face bending sample 3Back bending sampling 4Side bending sample

5- Impact sample (3),(6),(9) and (12) are the positioning marks for horizontal fixed position

4.3.7 For tensile sample, machining work should be used to remove high allowance of the weld, and the sample

should comply with the following regulations:

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(a) The position of the bending sample when the tensile sample is homogeneous pipe

(b) When impact test is not required


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4.3.7.1 For test piece with thickness less than or equal to 30mm, total thick sample should be used.

4.3.7.2 For test piece with thickness more than 300mm, total thick sample can be used according to the

condition of the testing machine, it is also ok to cut the total thick sample into sub-samples with the same

thickness and minimum amount by mechanical cutting. All qualified sub-samples can take stead of a qualified

total thick sample.

4.3.7.4 For plate test piece and pipe test piece with external diameter of more than 76mm, plate tensile sample

with shoulder should be used. The shape and size should comply with the regulations in Fig.4.3.7-2 .

Fig. 4.3.7-1 Tensile Sample of Plate Test Piece And Pipe Test Piece With External Diameter More Than 76mm

T- Thickness of the test piece; t- Thickness of the sample; W- The width of the sample tensile face is more than

or equal to 25mm; HK-The widest width of the weld h- gripping part length, based on the requirement of the

clamp of the testing machine; L- Sample length; R- corner radius

Fig.4.3.7-2 Tensile Sample of Pipe Test Piece With External Diameter Less Than Or Equal To 76mm

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Plate Pipe


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4.3.7.5 For pipe test piece with external diameter less than or equal to 76mm, total cross section tensile sample

can also be adopted. The shape and size of sleeve total cross section tensile sample should comply with the

regulations in Fig.4.3-7-3

Fig. 4.3.7-3 Sleeve Total Cross Section Tensile Sample

4.3.8 For bending sample, remove the height allowance of weld by mechanical machining. As to the stretch

face of face bending and back bending sample, at least one side of the original surface of the Parent Metal

should be withheld, and the machining incision should be parallel to the longitudinal axis. The shape and size

of the bending sample should comply with the following regulations:

4.3.8.1 Horizontal face bending and back bending sample should comply with the regulations in Fig. 4.3.8-1

and table 4.3.8. When the thickness of the test piece is over 10mm, remove surplus thickness from the

compression face of the sample.Size of Bending Sample Table 4.3.8

Thickness of The Test Piece T Thickness of The Sample t

1.5T


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4.3.8.2 Horizontal side bending sample should comply with the regulations in Fig. 4.3.8-2. When the thickness

of the test piece is less than 40mm, total thick side bending sample should be used with the thickness equal to

the thickness of the test piece, and when the thickness of the test piece is more than or equal to 40mm,

multi-samples with equivalent width 20~30mm can be cut in the direction of the thickness of the test piece to

take stead of a total thick sample.

4.3.8.3 Vertical bending sample should comply with the regulations in Fig 4.3.8-8-3. The vertical axis of the

sample should be parallel to the weld.

Fig. 4.3.8-2 Horizontal Side Bending Sample

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Plate Pipe

(a) Pipe and plate face bending

Plate Pipe

(b) Pipe and plate back bending

Fig. 4.3.8-1 Horizontal Face Bending And Back Bending Samples


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Fig. 4.3.8-3 Vertical Bending Sample

Note: B is the width of the sample, width of the plate test piece B=30mm;

Width of sample of the pipe test piece B=t+(/20)mm, and 10B38mm

(whose- external diameter of the pipe, t- thickness of the sample)

4.3.9 Mechanical machining should be applied to impact sample, whose shape and size should comply with

current national standard Impact Test Method For Welding Joint. The sample should be vertical to the weld

axis, the gap axis should be vertical to the Parent Metal surface, the gap axis of the sample in weld zone should

be in the center line of the weld, and the gap axis of the sample in heat affected zone should meet the axis of the

sample within heat affected zone (See Fig. 4.3.9).

Fig. 4.3.9 Cutting Position of The Impact Sample

1- Weld metal; 2- Heat affected zone; 3- Impact sample; 4- Center line of the sample

t1-The distance between the sample and the edge of the parent material, t11mm;

t2- The distance between the center line of the sample and the edge of the Parent Metal

19

Face bending Back Bending

(a) Heat affected zone

(b) Weld metal


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4.3.10 Mechanical test method should comply with the following regulations:

4.3.10.1 Tensile test method should comply with current national standard Metal Tensile Test Method.

4.3.10.2 Bending test should comply with current national standard Metal Bending Test Method GB232, and

the diameter of the bent axle of various parent metals used in bending test should comply with the regulations

in table 4.3.10. For the welding joint of different parent metals, the bent axle with larger diameter should be

adopted.

Diameter of the bent axle Table 4.3.10

Parent Metal categoryThickness of the

sample

Diameter of the bent

axle

Distance between the

abutments

All the Parent Metals Except

Category 25 and 51

t 4t 6t+3

Category 25 T 6 2/3t 8 2/3t+3

Category 51 t 8t 10t+3

4.3.10.3 Impact test method should comply with the current national standard Metal Charpy Indentation

Resilience Test Method (for V Type Notch) GB2106 or Metal Charpy Indentation Resilience Test

Method at Low Temperature GB 4159.

4.3.11 The qualified index in mechanical test should comply with the following regulations:

4.3.11.1 When the parent metals of the sample in the tensile test are the same kind of material, the tensile

strength of each sample should not be lower than the lower limit of the standard value of parent materials

tensile strength. When the sample has two kinds of parent metals, the tensile strength of the sample should not

be lower than the lower limit of the standard value of tensile strength of the Parent Metal with lower tensile

strength; Sample that breaks on the Parent Metal outside of the weld or weld junction, whose tensile strength is

no lower than the lower limit of the standard value of parent materials tensile strength, can be judged qualified.

4.3.11.2 In bending test, the bending angle is 180. When the bending axle of the sample bends to the specified

angle, its stretching plane must not have over 3mm long cracks in any direction without counting the cracks t

the edges and corners of the sample, however, the cracks at the edges and corners caused by slag

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inclusions or other internal defects should be counted. When making bending test, the weld center on the

sample should be aligned with the axis of the bending axle, and all the weld and heat affected zone should be

within the bending scope of the sample.

4.3.11.3 The qualified index of impact test should comply with the regulations in the design documents.

4.3.12 In mechanical test, when a sample fails to be qualified, double sampling should be made from the

original test piece and test again, and if still fails, this welding procedure should be judged disqualified, and the

welding procedure needs to be modified to make welding procedure qualification again.

4.3.13 When the design documents has test requirements to the welding joint such as metallurgical phase,

erosion resistance and hardness etc., test items should be added in the welding procedure qualification

according to the requirements. The test method and qualified index should comply with the regulations in the

design documents.

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5. Examination of Welders


5.1.1 All the welders that work within the scope of this code should be examined following the regulations in

this chapter.

5.1.2 Company welder exam committee is responsible for organizing and implementing the welder exam,

which can be entrusted to authorized welder exam committee to organize.

5.1.3 Company welder exam committee is made up of welding engineers, radiography inspectors and welding

technicians.

5.1.4 Company welder exam committee should have corresponding welding equipment, place, test piece and

sample processing equipment, test and detection method.

5.1.5 Welder exam committee is responsible for reviewing the exam qualification of the welder, defining exam

content, providing welding guide book, supervision exam, assessing exam result, signing certificate,

establishing welder archive and examining and approving welder exam exemption qualification.

5.1.6 Welders that apply to participate in the exam should have junior high school degree or above, have taken

professional training, have the ability to assume welding work independently, and can participate in the exam

after approved by welder exam committee.

5.1.7 Welder exam includes two parts: basic knowledge and operation skills. The welder cannot participate in

the operation skill exam until they have qualified in the basic knowledge exam.

5.1.8 Basic knowledge exam should contain the following content:

5.1.8.1 Using and maintenance of the welding equipment and tools, and relevant safety protection skills

5.1.8.2 General knowledge about metal materials and welding materials and service regulations

5.8.1.3 Welding operation procedure, including welding method and characteristics, procedure parameters, line

energy, flow of slag, the effect of protective gas, operation method, welding sequence, pre-heating and

post-heating etc.

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5.1.8.4 General knowledge about the type of detection, avoiding and elimination and prevention and dealing of

welding deformation

5.1.8.5 Necessary preparation of field welding, welding symbols in operating region and recognition

5.1.8.6 Safe operation knowledge

5.1.9 When welders with certificate take additional exam to the same welding method, basic knowledge exam

is not required. When changing welding method, basic knowledge of corresponding method should be

examined. After the welding procedure is qualified, welders that participate in the welding of test piece could

be exempted from participating in corresponding basic knowledge and operation skills exams.

5.1.10 In the welder operation skills exam, the welding procedure must comply with the requirements in the

design documents.

5.1.11 Welder who failed in the basic knowledge exam or operation skills exam will still has one chance to

makeup, and if failed again, he has to be trained for a period of time to take the exam.

5.1.12 The effective period of the qualified items is three years, and the following regulations should be met:

5.1.12.1 If one of the following regulations is meet, welder who has stopped welding for six months can resume

welding in his original qualified items.

(1) Take operation skills exam of that item and qualified.

(2) Weld plate butt weld with minimum 300mm in length to the corresponding item on spot, or weld pipe butt

weld with at least one weld junction and perimeter no less than 360mm to the corresponding item on spot,

and all qualified in radiographic test.

5.1.12.2 Within the effective period of the qualified item, if one pass rate of the welding is above 90%

according to the statistics of the negative films of radiographic test, or is above 99% according to the statistics

of weld extended meter of ultrasonic test, the three years effective period of that qualified item can be

prolonged.

5.1.12.3 For welder whose field welding quality is bad as put forward by the company quality inspection

department, after approved by company welder exam committee, his certificate of approval can be revoked, and

the welder cannot take the exam again until he has studied and has been trained.

5.1.13 After approved by welder exam committee, welders who have passed the exam based on other exam

rules can engage in the welding work within the scope of application of this code, and his accepted item should

comply with the regulations in this chapter.

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5.1.14 Welder exam record, welder exam result registration form and welder certificate of approval shall adopt

the from the annex B of this code.

The items in welder exam result registration from and welder certificate of approval can be expressed using

code. The express method of code is as follows:

X1X2X3X4X5

Where:

X1 Class number of welding method, and the class number of combined welding method can be

expressed as X1/X2;

X2 Test piece category and position class number;

X3 Class number of parent material, the category number of steels of different kinds can be expressed

as X3/X3;

X4Class number of welding material;

X5 Additional code, welding joint with underlay in the back or double face welding joint can be

expressed as D, and the code of single face butt welding joint or all through fillet welding joint

can be omitted.

5.2 Content And Method of Operation Skills Exam

5.2.1 The welding method of the exam should be classified according to the regulations in table 5.2.1. The

exams to various welding methods cannot take place of each other. For exam to combined welding method, it is

all right to weld a test piece according to the combined welding method, and it is also ok to weld test pieces

separately according to each welding method with the thickness of the test piece complying with the

regulations in sub-clause 5.2.5 of this code.

Welding Method Classification Table 5.2.1

Welding Method Classification Code

Covered Arc Welding D

Oxyacetylene Welding Q

Argon-Shielded Tungsten Arc Welding Ws

Consumable Electrode Argon Arc Welding Rz

Carbon Dioxide Welding RB

Submerged Arc Welding M


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24

Test Piece And Weld Category And Position Class Code Table 5.2.2

Test piece and weld category Code Position classification Code

Plate test piece P Flat welding F

Pipe test piece T Vertical welding V

Pipe and plate test piece TPHorizontal welding or vertical fixed

overhead welding

H

O

Bevel weld G Pipe horizontally fixed A

Fillet weld F Pipe fixed with 45inclination Ai

Pipe rotates horizontally Fr

5.2.2.1 Test piece of exam includes: plate test piece with bevel butt weld, plate test piece with fillet weld, pipe

test piece with bevel butt weld, pipe test piece with fillet weld, pipe test piece with fillet weld plus pipe test

piece with all through fillet weld.

5.2.2.2 Plate test piece with bevel butt weld and plate test piece with fillet weld has four positions, i.e. flat

welding position, vertical welding, horizontal welding and overhead welding (see Fig. 5.2.2-1 and Fig. 5.2.2-2).

Pipe test piece with bevel butt weld has four positions, i.e. horizontal rotate, vertically fixed, horizontally fixed

and 45inclination (see Fig. 5.2.2-3). Pipe plate test piece with fillet weld and pipe plate test piece with all

through fillet weld has three positions, i.e. horizontal welding, horizontally fixed and overhead welding (see Fig.

5.2.2-4, Fig. 5.2.2-5 and Fig. 5.2.2-6).

(a) Flat welding F (b) Vertical welding V (c) Horizontal welding H (d) Overhead welding O

Fig. 5.2.2-1 Plat test piece with bevel butt weld (PG)


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(a) Horizontal welding H (b) Horizontally Fixed A (c) Overhead welding O

Fig. 5.2.2-4 Pipe test piece with fillet weld (TF)

26

(a) Flat welding F (b) Horizontal welding H (c) Vertical welding V (d) Overhead welding O

Fig. 5.2.2-2 Plat test piece with fillet weld (PF)

(a) Horizontal rotate F (b) Vertically fixed H (c) Horizontally fixed A (d) All 45Ai

Fig. 5.2.2-3 Pipe test piece with groove butt weld (TG)


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Fig. 5.2.2-6 Pipe plate test piece with all through fillet weld (TPG)

5.2.3 Following the regulations in Fig. 5.2.3 to check horizontally fixed welding and vertically fixed welding

on the same pipe test piece. The joint position of the two positions should be included in the exam, and if the

joint position fails to pass the check, both the two positions will be judged disqualified.

Fig 5.2.3 Check horizontally fixed welding and vertically fixed welding on the same pipe

5.2.4 Test piece and Approval Range of position for the exam should comply with the regulations in table

27

Examination position of

vertically fixed welding

Examination position of

horizontally fixed welding


Fig. 5.2.2-5 Weld test pieces of tube plate angle


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Test Piece And Approval Range of Position For The Exam Table 5.2.4

Test piece and position for the

exam

Approval Range

Bevel butt weld Fillet weld

Category

of test

piece

(code)

Position (code)

Plate

Pipe with

outside

diameter

600mm

Pipe with

outside

diameter

600mm

Plate

Pipe or

pipe

plate

(not all

through)

Pipe or pipe plate (all

through)

Flat welding (F) F Fr F

Horizontal

welding (H)H, F H, Fr H, F

Vertical welding

(V)V, F Fr V, F

Overhead welding

(O)O, F Fr O, F

Vertical welding +

overhead welding

(V + O)

F, V, O A F, V, O

Plate test

piece with

bevel butt

weld (PG)

Horizontal

welding + vertical

welding +

overhead welding

(H + V + O)

All

positions

All

positions

All

positions

Flat welding (F) F

Horizontal

welding (H) H, F

Vertical welding

(V) V< F

Plate test

piece with

fillet weld

(PF)

Overhead welding

(O) O, F


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Test piece and position for the

examApproval Range

Bevel butt weld Fillet weld

Category

of test

piece

(code)

Position (code)Plate

Pipe with

outside

diameter

600mm

Pipe with

outside

diameter

600mm

PlatePipe or pipe plate

(not all through)

Pipe or pipe plate

(all through)

Horizontal rotate

(Fr)F Fr Fr Fr Fr

Vertically fixed

(H)H, F H, Fr H, Fr H, Fr H, Fr

Horizontally fixed

(A)F, V, O A, Fr A, Fr A, Fr A, Fr

45inclination

(Ai)

All

positions

All

positions

All

positions All positions All positions

Pipe test

piece with

bevel butt

weld (TG)

Horizontally fixed

+ vertically fixed

(A + F)

All

positions

All

positions

All

positions All positions All positions

Horizontal

welding (H)

H, Fr

Horizontally fixed

(A) All positions

Pipe test

piece withfillet weld

(TF) and

pipe plate

test piece

with fillet

weld (TPF)

(not all

through)

Overhead welding

(O) O, Fr, H

Horizontal

welding (H) H, Fr H, Fr

Horizontally fixed

(A) All positions All positions

Pipe plate

test piece

with fillet

weld

(TPG) (not

all through)

Overhead welding

(O) O, Fr, H O, Fr, H

Note: (a) Welder who has passed the exam to the test piece with obstruction does not have to take exam to the

test piece without obstruction in the corresponding position.

(d)In vertical welding exam, if the welding direction is changed, the exam should be restarted.


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5.2.5 The Approval Range of the thickness of test piece for exam should comply with the following regulations:

5.2.5.1 The Approval Range of the thickness of plate and pipe bevel butt weld should comply with the

regulations in table 5.2.5. When the thickness of the test piece meets the requirements of sub-coat, filling and

finishing layer deposit welding, the upper limit of the thickness is not limited.

5.2.5.2 The Approval Range of the thickness of fillet weld test piece is not limited.

The Approval Range of The Thickness of Test Piece With Bevel Butt Weld (mm) Table 5.2.5

The thickness of test piece for exam T Approval Range

10 2T

10~20 5~2T

20 5

5.2.6 The Approval Range of the outside diameter of the pipe test piece should comply with the regulations in

table 5.2.6.

The Approval Range of The Outside Diameter of Pipe Test Piece (mm) Table 5.2.6

The outside diameter of test piece for exam D Approval Range

25 D

25~7625

76 76

5.2.7 The classification and Approval Range of the Parent Metal of test piece for exam should comply with the

following regulations:

5.2.7.1 The classification to the Parent Metal of test piece for exam should comply with the regulations in

sub-clause 4.2.3 of this code, with its Approval Range complying with the regulations in table 5.2.7-1. For

parent metals that cannot be classified according to sub-clause 4.2.3 of this code, exams should be held

separately.

The Approval Range of The Parent Metal of Test Piece For Exam Table 5.2.7-1

Category number the Parent Metal of test piece for

exam DApproval Range

P1~P7

Parent metals with category number P1~P7, parent

metals with lower category number or joints of

different kinds made by Parent Metal with category

number P1~P7 and Parent Metal with lower

category number.

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Table 5.2.7-1 continued

Category number the Parent Metal of test piece for

exam DApproval Range

P9A, P9B, P11

Parent metals with category number P9A, P9B, P11,

parent metals with lower category number or jointsof different kinds made by Parent Metal with

category number P9A, P9B, P11 and Parent Metal

with lower category number.

P22, P25

Parent metals with category number P22, P25,

parent metals with lower category number or joints

of different kinds made by Parent Metal with

category number P9A, P9B, P11 and Parent Metal

with lower category number.

P8, P21, P31, P32, P51Parent Metal with category number P8, P21, P31,

P32, P51

P41~P43, P45Parent Metal whose category number is one of

P41~P43 and P45.

5.7.2.2 When no bending property and other additional properties of test piece for exam is required, the

substitution of the Parent Metal of test piece for exam should follow the regulations in table 5.2.7-2, however,

the welding material must match the former parent material.Substitution of Parent Metal of Test Piece For Exam Table 5.2.7-2

Original regulated Parent Metal of test piece Substituted Parent Metal of test piece

Low alloys steel Carbon steel

Cr-Mo series refractory steel Carbon steel or low alloys steel

Austenitic stainless steel Carbon steel or low alloys steel

Aluminum magnesium alloys Commercial purity aluminum

Nickel and nickel-based alloys Austenitic stainless steel

5.2.8 Classification and Approval Range of welding materials should comply with the following regulations:

5.2.8.1 Classification and recognition of flux coated welding rod should comply with the regulations in table

5.2.8.2 When changing welding wire type, welding flux, protective gas and tungsten electrode kind, exams do

not have to be held separately.

5.2.8.3 When special welding rod or special welding wire such as special sub-coat welding rod, upward

welding rod of vertical welding and flux-cored wire is adopted, exams should be held separately.

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Classification And Approval Range of Flux Coated Welding Rod Table 5.2.8

Category code Name Type Approval Range

F1

Welding rods except E

15 and E16

F1

F2

Carbon steel welding rod

and other alloys steel

welding rod except

austenitic stainless steel

welding rod E15, E16 F1, F2

F3 E16 F3

F4


welding rodE15 F3, F4

F5Nickel and nickel alloys

welding rod F3, F4, F5

5.2.9 Once the one side welding without backing to the test piece for exam is qualified, qualifications of one

side welding with backing and double face welding can be achieved. Exam qualifications of one side welding

with backing and double face welding admit reciprocally.

5.2.10 The shape and size of test piece for exam should comply with the regulations in table 5.2.10. The shape

and size of bevel should also comply with relevant regulations.

Shape And Size of Test Piece For Exam (mm) Table 5.2.10

Category of

test pieceWelding method L B H

Submerged arc welding, consumable electrode

argon arc welding, carbon dioxide welding500 250

Plate test

piece with

bevel buttweld

Others 300 250

Submerged arc welding, consumable electrode

argon arc welding, carbon dioxide welding500 100 100Plate test

piece with

fillet weld Others 300 100 100

Pipe test

piece with

Bevel butt

weld

200

Pipe test

piece with

fillet weld

200 2D

Pipe plate

test piece

with fillet

weld

60

Note: The meanings of the L, B and H in the table are the same to those in Fig. 5.2.2-1~6.


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5.3.4.3 Besides the two clauses mentioned above, commercially pure titanium test piece still has to comply

with the regulations in table 11.3.3.

5.3.5 When bending property inspection is required, sample amount should comply with table 5.3.5, and

sampling of test piece should comply with the regulations in sub clauses 4.3.6 and 4.3.8 of this code. The test

method and qualified indexes should comply with the regulations in sub clauses 4.3.10 and 4.3.11 of this code.

Sample amount in bending test Table 5.3.5

Bending sample amount (piece)Thickness of Parent Metal T

(mm) Face bending Back bending Side bending

1.5T


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6 Welding of Carbon Steel And Alloys Steel


6.1.1 This chapter applies to covered arc welding, argon arc welding, carbon dioxide welding, submerged arc

welding and oxyacetylene welding for field carbon steel with carbon content less than or equal to 0.30%, low

alloys structured steel, low temperature steel, refractory steel, stainless steel and refractory and anticorrosion

high alloys steel welding equipment and pipe.

6.1.2 To make it convenient for welding and heat treatment, the weld should be kept away from stress raiser,

and the following regulations should be met:

6.1.2 When grouping steel plate reel pipe or equipment, shell ring and shell ring of vessel, shell ring and end

plate, the distance between two consecutive vertical welds should be more than 3 times of wall thickness and

no less than 100mm, and the distance between two consecutive vertical welds on a same shell ring should not

be less than 200mm.

6.1.2.2 The distance between the welder center of the pipe on the heating surface of the heating furnace and the

curvature point of pipe, outer wall of collecting box, bracket, hanger should not be less than 70mm, and the

distance between two butt welds on a same straight pipe should not be less than 150mm.

6.1.2.3 The distance between the butt weld center of other pipes except welding pipes and molding pipes and

the curvature point of pipe should not be less than the outside diameter of the pipes, and no less than 100mm.

The distance between the butt weld of pipe and bracket and hanger edge should not be less than 50mm. For the

distance between central planes of two butt welds: when the nominal diameter is more than or equal to 1500,

the distance should not be less than 150mm, and when the nominal diameter isles than 150mm, the distance

should not be less than the outside diameter of the pipe.

6.1.2.4 It is inappropriate to bore on the welds and their edge, if unavoidable, the regulations in sub clause

11.3.9 of this code should be met.

6.1.3 The shape and size of weld bevel should comply with the regulations in the design documents and

welding guide book. When no regulation is available, the type and size of the bevel of submerged arc welding

weld should comply with current national standard Basic Type and size of the bevel of Submerged Arc

Welding Weld GB986, and the type and size of the bevel of other welds should comply with the regulations in

sub clause C.0.1 in annex C.

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6.2 Preparations Before Welding

6.2.1 For weldment cutting and bevel processing, it is appropriate to adopt mechanical methods, and it is also

all right to adopt hot working methods such as plasma arc and oxyacetylene flame. If hot working methods are

adopted, the oxide skin on the bevel surface, slag and surface layer that affect the joint quality must be removed,

and the surface should be finished.

6.2.2 Before grouping weldments, oil, painting, encrustation, rust, burr and galvanizing coat should be cleared

from the bevel and its internal and external surface within no less than 10mm scope, and no defects such as

crack and interlay are allowed.

6.2.3 Except pipes that requires cold drawing and cold compress as regulated in design, the weldments should

not be grouped forcibly.

6.2.4 When grouping butt welds of pipes or pipe fittings, the inner wall should be aligned, with stagger amount

no more than 10% of the wall thickness, and no more than 2mm.

6.2.5 When grouping butt welds of equipment and vessels, the stagger amount should comply with the

regulations in table 6.2.5 and the following regulations.

Stagger amount when grouping butt welds of equipment and vessels (mm) Table 6.2.5

Stagger amount

Thickness of Parent Metal Vertical weld Circumferential weld

12 1/4 1/4

1220 3 1/4

2040 3 5

4050 3 1/8

50

1/16,

and not greater 10

1/8

and not greater 10

Note: in the table refers to the thickness of Parent Metal for work piece

6.2.5.1 Only stagger from vertical and circumferential weld of one side welding is allowed, with maximum

stagger amount 2mm.


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6.2.5.2 When grouping clad steel plate, cladding surface should be made the benchmark, with stagger amount

no more than 50% of the thickness of the steel plate cladding, and no more than 1mm.

6.2.6 When grouping butt weldment with unequal thickness, end face of thin weldment should be within the

end face of thick weldment. When the stagger amount of inner wall exceeds the amount regulated in sub clause

6.2.4 and sub clause 6.2.5 of this code or the stagger amount of outer wall is more than 3mm, the weldment

should be processed (Fig. 6.2.6).

(a)

(b)

Fig. 6.2.6 Processing to bevel of butt weldment with unequal thickness

Note: In consideration of length limit as applied to pipes, the 15in Fig (a), (b) and (c) is allowed to

change to 30.

37

a)Unequal inner wall size

b)Unequal outer wall size

(c) Unequal inner and outer

wall size(d) Whittling down when inner

wall size is unequal


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6.2.7 When grouping weldments, they should be leveled securely, and measures should be taken to prevent

from the additional stress and deformation caused in welding and heat treatment process.

6.2.8 When semi automatic or automatic welding is adopted, run on plate and quench plate of the same kind of

material as the Parent Metal or of the same category number should be installed on both ends of vertical weld.

6.2.9 Before welding, measures should be taken to prevent welding splash from contaminating the surface of

the weldment within 100mm area on both sides of the bevel of stainless steel weldment.

6.2.10 Welding rod and welding wire must be dried before put into use, and kept dry when using. The oil stain

and rust etc. on the surface of welding wire must be cleared before it is used.

6.3 Welding Procedure Requirements

6.3.1 The selection of welding rod and welding wire is determined after considering the factors such as

chemical composition and mechanical properties of the parent material, crack resistance of the welding joint,

pre-heating before welding, heat treatment after welding, service conditions and construction conditions etc.

and complying the following regulations:

6.3.1.1 Good properties of welding processing.

6.3.1.2 When welding the same kind of steels, the properties and chemical compositions of the weld metal

should be comparable with that of the parent material.

(1) For low temperature steel, welding material suitable for the using temperature of the Parent Metal should

be selected.

(2) For refractory and anti corrosion high alloys steel, nickel-based welding material can be selected.

6.3.1.3 Selection of welding rod when welding steels of different kind.

(1) When the parent metals at both sides are all non-austenitic steel or austenitic steel, the welding material can

be selected according to the Parent Metal at the side with lower alloys content or with medium alloys

content.

(2) When the Parent Metal at any of the two sides is austenitic steel, 25Cr-13Ni welding material or welding

materials with more nickel content should be selected.

6.3.1.4 When welding clad steel plate, corresponding welding materials should be selected for bed layer and

cladding, and intermediate layer welding material should be selected for the welding at the intermediate of bed

layer and cladding.

6.3.1.5 Selection of carbon steel and alloys steel welding material should comply with the regulations in sub

clause D.0.1 and D.0.2 in Annex D of this code.

6.3.2 For submerged arc welding, the welding flux selected should match the Parent Metal and the welding

wire.

6.3.3 Tack weld should comply with the following regulations:

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6.3.3.1 When welding tack weld, which should be welded by qualified welder, welding material and welding

procedures that are the same to that of the root pass should be adopted.

6.3.3.2 The length, thickness and interval of the tact weld should be enough to ensure that the weld will not

crack under normal use.

6.3.3.4 Before welding root pass, check the tact weld first, and clear the defects if any before welding.

6.3.3.4 The material of clamp apparatus that welded with the Parent Metal should be of the same kind as the

Parent Metal or of the same category number. When removing clamp apparatus, the Parent Metal should not be

damaged. After removed, the remaining burr should be polished.

6.3.4 Arc strike and current test is strictly prohibited on the surface of the Parent Metal outside of the bevel, and

measures should be taken to prevent the electrical arc from damaging the surface of the parent material.

6.3.5 For weldment with nickel content more than or equal to 3% or total alloys elements content more than 5%,

in argon arc bottoming welding, argon gas or other protective gas should be filled at the inside of the weld, or

take other measures to prevent the inside weld metal from being oxidized.

6.3.6 Adopt reasonable welding method and welding sequence in welding.

6.3.7 Ensure the quality at arc starting and arc stopping place in welding. Fill up the arc crater when stopping

the arc. The interlayer joints of multi-layer welding should be staggered.

6.3.8 When welding pipe, prevent draught in the pipe.

6.3.9 Each weld should be welded in one time, unless required by procedure or inspection to interrupt. When

welding is interrupted for some reason, measures such as heat preservation or post heating etc. should be taken

to prevent crack from being generated according to procedure requirements. Before rewelding, check the

surface of weld pass, and continue to weld after confirmed that there is no crack.

6.3.10 For pipe weld that requires prestretching and precompression, The clamp apparatus used in grouping

should not be removed until overall weld welding and heat treatment is completed and qualified after

inspection.

6.3.11 Welding to low temperature steel, austenitic stainless steel, refractory and anti corrosion alloys steel,

austenitic and non-austenitic steel joints of different kinds should comply with the following regulations:

6.3.11.1 Within the scope regulated in the welding guide book, procedures such as low current, short electrical

arc, fast welding and multiplayer and multi pass welding should be adopted under the condition that through

welding and good fusion is guaranteed. Also, the interlayer temperature should be controlled.

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6.3.11.2 For both sides welding with high anti corrosion property requirements, weld the layer which contact

the corrosive medium at last.

6.3.11.3 After low temperature steel welding has completed, it is suggested annealing treatment to the surface

of welding pass be conducted.

6.3.12 Clad steel welding should comply with the following regulations:

6.3.12.1 It is strictly prohibited to weld cladding using welding rod for bed layer and intermediate layer.

6.3.12.2 When welding intermediate layer, it is advisable to select small welding line energy.

6.3.12.3 Before welding cladding, clean the splash on the surface of the cladding bevel.

6.3.13 Conduct acid cleaning and passivating treatment to austenitic stainless steel weld and the surface around

it according to design regulations.

6.4 Pre-heating before welding and heat treatment after welding

6.4.1 Pre-heating before welding and heat treatment after welding should be conducted after the factors such as

hardening capacity of the steel, weldment thickness, structure rigidity, welding method and service conditions

etc. have been considered.

6.4.2 The interlayer temperature of weldment that requires pre-heating before welding should be within the

regulated pre-heating temperature.

6.4.3 When the weldment temperature is below 0, all the steel weld should be pre-heated to over 15

within 100mm area around the starting welding point.

6.4.5 For weld with stress corrosion, heat treatment after welding should be conducted.

6.4.5 When welding of non-austenitic steel different kinds, pre-heating temperature before welding and heat

treatment temperature after welding should be selected according to the steel at the side with worse weldability,

with the heat treatment temperature after welding no higher than the critical temperature AC1of the other side of

steel.

6.4.6 The heat treatment temperature after welding of quenched and tempered steel should be lower than its

tempering temperature.

6.4.7 The heating perimeter of pre-heating before welding should make the weld center as the benchmark, with

the thickness of each side no less than 3 times of the weldment thickness. The heating perimeter of heat

treatment after welding is defined with the thickness of each side no less than 3 times of the weldment width.

Conduct heat preservation at places beyond heating zone.

6.4.8 During pre-heating before welding and heat treatment after welding, the temperature of the inner wall and

outer wall of the weldment should be uniform.

6.4.9 During pre-heating before welding and heat treatment after welding, the temperature should be measured

and recorded, temperature measurement point and amount should be reasonable, and temperature measurement

meter should qualified in metrological verification.

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6.4.10 Heat treatment after welding should be conducted in time to steels that are easy to generate welding

delay cracks, if cannot, uniformly heat the steels to 200~300 immediately after welding, and conduct heat

preservation and slow cooling with the requirements to heating perimeter the same to that of heat treatment

after welding.

6.4.11 The temperature of preheating before welding and heat treatment after welding should comply with the

regulations in the design documents and welding guide book. If no regulations are available, the temperature of

preheating before welding and heat treatment after welding to normal pipe welding should comply with the

regulations in table 6.4.11, and the temperature of preheating before welding and heat treatment after welding

to equipment and vessel welding should comply with the relevant regulations in current national standard

Steel Pressure Vessel GB150.

Procedure Conditions For Pre-Heating Before Welding And Heat Treatment

After Welding To Normal Pipes Table 6.4.11

Pre-Heating Before Welding Heat Treatment After Welding

Steel Type Wall Thickness

(mm)

Temperature ()Wall Thickness

(mm)

Temperature ()

C 26 100~200 30

CMn

600~650

MnV 560~590

C0.5Mo 600~650

0.5Cr0.5Mo

15 150~200 20

1Cr0.5Mo 10 150~250 10

650~700

1Cr0.5MoV

1.5Cr1MoV

2.25Cr1Mo

200~300 6

5Cr1Mo

700~750

9Cr1Mo

2Cr0.5Mo

WV

6

250~350 Not limited

750~780


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3Cr1MoVTi

12Cr1MoV

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6.4.12 When argon-shielded tungsten arc welding is adopted for bottoming, the lower limit of the pre-heating

temperature before welding can be reduced to 50 according to the regulations in table 6.4.11.

6.4.13 The heating rate, constant temperature time and cooling rate of heat treatment after welding should

comply with the following regulations:

6.4.13.1 When temperature rises to over 400, the heating rate should not exceed (20525/)/h and not

exceed 330/h.

6.4.13.2 The constant temperature time of heat treatment after welding should be regulated as constant in 1h for

each 25mm thick wall, and no lower than 15min, and during constant temperature period, the difference

between the highest temperature and the lowest temperature should not be less than 65.

6.4.13.3 After constant temperature period, the cooling rate should not be less than (6525/)/h, and no

lower than 260. Natural cooling is all right when the temperature is below 400.

6.4.14 For welds that undergone repairs after heat treatment or welds whose hardness exceeds the regulated

value as found during inspection, heat treatment should be conducted again.


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7. Welding of Aluminum And Aluminum Alloys


7.1.1 This chapter applies to manual argon-shielded tungsten arc welding and consumable argon arc welding

for field commercial purity aluminum and aluminum alloys welding equipment and pipe.

7.2 Preparation before welding

7.2.1 The selection of welding wire is determined after considering the factors such as chemical composition

and mechanical properties of the Parent Metal and service conditions etc. and complying the following

regulations:

7.2.1.1 For pure aluminum welding, welding wire with purity close to that of the Parent Metal should be

selected.

7.2.1.2 For aluminum magnesium alloys welding, welding wire with magnesium content equal to or slightly

higher than that of Parent Metal should be selected.

7.2.1.3 For aluminum manganese alloys welding, welding wire with composition close to that of the Parent

Metal or aluminum silicon alloys welding wire should be selected.

7.2.1.4 For welding of aluminum alloys of different kinds, welding wire with tensile strength close to that of the

Parent Metal of the side with higher tensile strength should be selected.

7.2.1.5 For aluminum and aluminum alloys welding, parent sliver can also work as filler metal.

7.2.1.6 Selection of aluminum and aluminum alloys welding wire should comply with the regulations in sub

clause C.0.2 in annex C of this code.

7.2.2 Weldment bevel preparation should comply with the following regulations:

7.2.2.1 The shape and size of bevel should comply with the regulations in the design documents and welding

guide book. When no regulation is available, the type and size of the bevel should comply with the regulations

in sub clause C.0.2 in annex C.

7.2.2.2 Mechanical methods or plasma arc cutting should be adopted in bevel processing. Clean the bevel

surface after cutting to make it flat and smooth, without burr and fash.

7.2.3 Cleaning before welding should comply with the following regulations:

7.2.3.1 Clean the weldment bevel, backing plate and welding wire before welding. The cleaning method is as

follows:

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First, use organic solvent such as acetone or carbon tetrachloride to remove the oil stain on the surface, with the

cleaning range on both sides of the bevel no less than 50mm. Then, file, scratch and mill the bevel and the

surface around it or using stainless steel wire brush until metallic luster is appeared. The steel wire brush should

undergone degrease treatment periodically.

7.2.3.2 After the oil stain is removed, adopt chemical method to remove the oxide film, for which NaOH

solvent with density 5%~10% can be used. Soak the welding wire in the solvent for 30~60s under 70 , then

use water to clean it, after that, soak it in HNO3with density around 15% for 2 min under normal temperature,

then, use warm water to clean it and keep it dry.

7.2.3.3 After cleaning, the welding wire should not have water stain, alkali stain or been stained.

7.2.4 Weldment grouping should comply with the following regulations:

7.2.4.1 When welding tact weld, welding wire and welding procedure for formal welding should be adopted,

and qualified welder is responsible for the welding.

7.2.4.2 The length, interval and height of the tact weld for equipment and vessel should comply with the

regulations in table 7.2.4-1, and the size of pipe tact weld should comply with the regulations in table 7.2.4-2.

Size of Tact Weld For Equipment And Vessel (mm) Table 7.2.4-2

LengthPlate Thickness Interval Weld Height

Vertical Weld Circumferential weld

1~3 20~60 1~3 5~15 10~20

2~8 60~180 3~4 15~25 20~30

8~14 180~250 3~6 20~30 30~40

14 250~350 4~6 30~50 40~70

Size of Pipe Tact Weld (mm) Table 7.2.4-2

Nominal Diameter Position And Amount Weld Height Length

50 Two symmetric points 5~10

50~150Rectangular

distributed 2~3 points5~10

150~200Rectangular

distributed 3~4 points

Determined based on

the thickness of the

weldment

10~20


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7.2.4.3 Check the tact weld before formal welding, and deal with the defect found in time. The oxide film on

the surface of tact weld should be cleaned, and finish its both sides to gentle slope.

7.2.4.3 When removing the positioning board, the Parent Metal should not be damaged, and the remaining

burrs should be finished to level with the Parent Metal surface.

7.2.5 When permanent backing plate is required to be added on the back of weld, the material of backing plate

should comply with the design regulations. If no regulations are available, the backing should have grooves on

it to accommodate weld root. When temporary backing plate is required to be added on the back of weld, the

material of backing plate should not have bad influence on weld quality.

7.2.6 The inner wall of pipe butt weld should be flat, with the stagger amount complying with the following

regulations:

7.2.6.1 When the wall thickness is less than or equal to 5mm, the stagger amount of inner wall should not be

more than 0.5mm.

7.2.6.2 When the wall thickness is more than 5mm, the stagger amount of inner wall should not be more

than 0.1mm, and no more than 2mm.

7.2.7 The stagger amount of butt weld for equipment and vessel should comply with the regulations in table

7.2.7.

Stagger Amount of Butt Weld For Equipment And Vessel Table 7.2.7

Stagger amount

Parent Metal thickness

Vertical weld Circumferential weld

5 0.5

5 0.1, and 2

0.2, and 5

7.2.8 When grouping butt weldment with unequal thickness, end face of thin weldment should be within the

end face of thick weldment. When the stagger amount of surface exceeds 3mm or the stagger amount of inner

wall exceeds 2mm, the weldment should be processed according to the regulations in sub clause 6.2.6 of this

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7.3 Welding Procedure Requirements

7.3.1 AC power supply should be adopted in manual argon-shielded tungsten arc welding, and DC power

supply should be adopted in consumable electrode argon arc welding with the welding wire connecting the

anode.7.3.2 Keep the weldment surface dry, and if no special requirements, pre-heating is not necessary.

7.3.3 Conduct test welding on the test coupons before welding, and do not begin formal welding until no gas

cavity is found.

7.3.4 It is suggested strong current fast welding method be adopted, however, the horizontal swing of the

welding wire should not exceed 3 times of its diameter.

7.3.5 Arc strike should be conducted on the run on plate, and arc quenching for vertical weld should be

conducted on quenching plate. The material of run on plate and quenching plate should be the same to the

parent material.

7.3.6 The end of welding wire for manual argon-shielded tungsten arc welding should not leave the argon

shield zone. It is suggested the included angle between the welding wire and the weld surface be 15 and the

included angle between the welding torch and the weld surface be 80~90.

7.3.7 In multi-layer welding, it is advisable to decrease welding layers and cool the interlayer temperature to

room temperature and no more than 65. The interlayer inclusions such as aluminum oxide should be cleared

by using mechanical method.

7.3.8 For vertical weld with thickness over 5mm, it is suggested two welders both faces synchronous welding

procedure be adopted.

7.3.9 When the front end of the tu

gb50236-98 welding code for construction and inspection of field equipment and industrial piping

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