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GB/T 37577-2019Welded large diameter steel pipes for low-temperature-service piping (English PDF)

低温管道用大直径焊接钢管

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

June 4, 2019

Implementation date

May 1, 2020

Scope

GB/T 37577-2019 is the English-translated version of 低温管道用大直径焊接钢管.

GB/T 37577-2019 is the Chinese standard "Welded large diameter steel pipes for low temperature service piping".

Its scope clause reads: This Standard specifies the ordering content, dimensions, shape, weight, technical requirements, test methods, inspection rules, packing, marking, and quality certification of welded large diameter steel pipes for low-temperature-service piping.

This Standard is applicable to welded large diameter steel pipes (hereinafter referred to as steel pipes) for low-temperature-service piping with a -20°C level ~ -196°C level and an outer diameter of not less than 114.3 mm.

Its clauses include ordering content; dimensions, shape, and weight; technical requirements; test methods; inspection rules; packing, marking, and quality certification.

It was issued by the State Administration for Market Regulation on JUNE 04, 2019 and took effect on MAY 01, 2020.

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Document preview — GB/T 37577-2019

National Standard of the People's Republic of China

ICS: 77.140.75
Classification: H 48

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

Foreword3
1 Scope4
2 Normative references4
3 Ordering content7
4 Dimensions, shape, and weight7
5 Technical requirements10
6 Test methods21
7 Inspection rules22
8 Packing, marking, and quality certification23
Appendix A (Informative) Common outer diameter and wall thickness24
Appendix B (Normative) Treatment methods of defects25

1 Scope

This Standard specifies the ordering content, dimensions, shape, weight, technical requirements, test methods, inspection rules, packing, marking, and quality certification of welded large diameter steel pipes for low-temperature-service piping.

2 Normative references

The following documents are indispensable for the application of this document.

For the dated references, only the editions with the dates indicated are applicable to this document. For the undated references, the latest edition (including all the amendments) are applicable to this document.

GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products

GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method

GB/T 223.9 Iron, steel and alloy - Determination of aluminium content - Chrome azurol S photometric method

GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium carbonate separation-diphenyl carbazide photometric method for the determination of chromium content

GB/T 223.14 Methods for Chemical Analysis of Iron, Steel and Alloy - The N- Benzoy-N-Phenylhydroxylamine Extraction Photometric Method for the Determination of Vanadium Content

GB/T 223.18 Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium Thiosulfate Separation Iodimetric Method for the Determination of Copper Content

GB/T 223.23 Iron, Steel and Alloy - Determination of Nickel Content - The Dimethylglyoxime Spectrophotometric Method

GB/T 223.25 Methods for chemical analysis of iron, steel and alloy - The dimethylglyoxime gravimetric method for the determination of nickel content

GB/T 223.26 Iron, Steel and Alloy - Determination of Molybdenum Content - The Thiocyanate Spectrophotometric Method

GB/T 223.40 Iron, Steel and Alloy - Determination of Niobium Content by the Sulphochlorophenol S Spectrophotometric Method

GB/T 223.58 Methods for chemical analysis of iron, steel and alloy - The sodium arsenite-sodium nitrite titrimetric method for the determination of manganese content

GB/T 223.62 Methods for chemical analysis of iron, steel and alloy - The butyl acetate extraction photometric method for the determination of phosphorus content

GB/T 223.68 Methods for Chemical Analysis of Iron, Steel and Alloy - The Potassium Iodate Titration Method after Combustion in the Pipe Furnace for the Determination of Sulfur Content

GB/T 223.84 Steel and iron - Determination of titanium content - Diantipyrylmethane spectrophotometric method

GB/T 223.86 Steel and iron - Determination of total carbon content - Infrared absorption method after combustion in an induction furnace

GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature

GB/T 229 Metallic Materials - Charpy Pendulum Impact Test Method

GB/T 241 Metal materials - Tube - Hydrostatic pressure test

GB/T 246 Metal materials - Tube - Flattening test

GB/T 2102 Acceptance, packing, marking and quality certification of steel pipe

GB/T 2650 Impact test methods on welded joints

GB/T 2651 Tensile test method on welded joints

GB/T 2653 Bend test methods on welded joints

GB/T 2975 Steel and Steel Products - Location and Preparation of Test Pieces for Mechanical Testing

GB/T 3531 Steel plates for low temperature pressure vessels

GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)

GB/T 19293 Method of X-ray radioscopy for butt-weld

GB/T 20066 Steel and Iron - Sampling and Preparation of Samples for the Determination of Chemical Composition

GB/T 20123 Steel and iron - Determination of total carbon and sulfur content - Infrared absorption method after combustion in an induction furnace (routine method)

GB/T 20125 Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method

GB/T 21835 Dimensions and masses per unit length of welded steel pipes

GB/T 26955 Destructive tests on welds in metallic materials - Macroscopic and microscopic examination of welds

NB/T 47014 Welding procedure qualification for pressure equipment

SY/T 6423.1 Petroleum and natural gas industries - Non-destructive testing (NDT) methods of steel tubes - Part 1: Radiographic testing of weld seam of welded steel tubes for detection of imperfections

SY/T 6423.2 Petroleum and natural gas industries - Non-destructive testing (NDT) methods of steel tubes - Part 2: Automated ultrasonic testing of the weld seam of welded steel tubes for the detection of longitudinal and/or transverse imperfections

SY/T 6423.4 Petroleum and natural gas industries - Non-destructive testing (NDT) methods of steel tubes - Part 4: Automated ultrasonic testing of seamless and welded steel tubes for the detection of laminar imperfections

SY/T 6423.5 Petroleum and natural gas industries - Non-destructive testing (NDT) methods of steel tubes - Part 5: Digital radiographic testing of the weld seam of welded steel tubes for the detection of imperfections

a) When the outer diameter is greater than 1422 mm, the shearing oblique shall not exceed 2.4 mm;

b) The shearing oblique of the remaining steel pipes shall not exceed 1.6 mm.

4 Dimensions, shape, and weight

4.6.2 Both end faces of the steel pipe shall be flat (not machined with groove).

According to the requirements of the purchaser, both end faces of the steel pipe may be machined with the groove. The groove size shall be indicated in the contract.

4.7 Weight

4.7.1 Steel pipes are delivered at actual weight and may also be delivered at theoretical weight. The theoretical weight of the steel pipe is calculated according to formula (1).

Where:

W - The weight per unit length, in kilograms per meter (kg/m); t - Nominal wall thickness, in millimeters (mm); D - Nominal outer diameter, in millimeters (mm).

4.7.2 The tolerance of the actual weight of the steel pipe from the theoretical weight is %-3+7.

5 Technical requirements

5.2.2.2 Before welding, the base metal may be preheated. Unless otherwise stipulated in the contract, the preheating temperature and the base metal range shall be determined by the manufacturer according to the base metal's delivery state, chemical composition, mechanical properties, welding properties, weldment thickness, degree of restraint of welded joint, welding method, etc., if necessary, determined by a test.

5.1 Designation and chemical composition of steel

5.1.1 The designation and chemical composition (heat analysis) of the steel shall comply with the requirements of Table 3. According to the requirements of the purchaser, through negotiation between the supplier and the purchaser, steel pipes of designations other than those specified in Table 3 may be supplied.

5.1.2 The permissible tolerances for chemical composition of the product shall comply with the provisions of GB/T 222. The permissible tolerances for chemical analysis of P and S in 08Ni3DR and 06Ni9DR steel products are:

P+0.003%, S+0.002%. welding with filler metal (GTAW), and a combination of processes between them.

5.2.3 Double-seam steel pipe

According to the requirements of the purchaser, through negotiation between the supplier and the purchaser, and indicated in the contract, for the steel pipe with an outer diameter of not less than 914 mm, double-seam steel pipe may be supplied. The weld seams of double-seam steel pipe shall be approximately 180° apart.

5.2.4 Steel pipe butt

Through negotiation between the supplier and the purchaser, and indicated in the contract, butt pipes may be supplied. The butt pipes shall comply with the following regulations:

a) The length of the short pipe used for butting shall not be less than 1500 mm;

b) On the circumferential weld seam of butt pipe, the circumferential spacing between the straight weld seams shall not be less than 50 mm;

c) The bending degree of the butt pipe shall comply with the provisions of 4.4.

5.3 Delivery state

Unless otherwise stipulated in the contract, the steel pipe shall be delivered in the state of welding or whole-pipe stress relief heat treatment. The recommended heat treatment system for steel pipes is shown in Table 4.

c) No cracks exceeding 3.2 mm in length or cracks and fractures exceeding 12.5% of the nominal wall thickness in depth shall be found on the base metal, heat-affected zone, or fusion line;

d) During the test, cracks appearing at the edge of the sample and having a length of less than 6.4 mm shall not be used as a basis for rejection.

5.7 Surface quality

5.7.1 Surface defects

The inner and outer surfaces of the steel pipe shall be free of folds, cracks, delamination, electric arc burns, and other defects whose depth exceeds the lower tolerance of the wall thickness. These defects shall be completely removed. The remaining wall thickness at the clearing shall be no less than the minimum allowable wall thickness.

5.7.2 Crater

There shall be no craters with a depth of more than 6.4 mm on the wall of the steel pipe. The crater length, in any direction, shall not exceed 0.5D. When the concave part is sharply scratched, the crater depth shall not exceed 3.2 mm.

When the concave part is sharply scratched, the sharp scratch shall be ground.

The depth and length of the concavity after grinding shall conform to the provisions of this subclause. The remaining wall thickness at the grinding location shall meet the corresponding requirements.

Note: The crater depth is the distance between the lowest point of the concavity and the original contour extension of the steel pipe.

5.7.3 Undercut

5.7.3.1 Any length of weld undercut with a depth of no more than 0.4 mm is allowed.

5.7.3.2 For a single undercut with a depth greater than 0.4 mm but not greater than 0.8 mm and not exceeding 0.1t and a length not exceeding 0.5t, and the undercut is no more than 2 over any 300 mm weld seam length, it shall be disposed of in accordance with B.1.2 a) in Appendix B.

5.7.3.3 Undercuts exceeding those specified in 5.7.3.2 shall be considered defects and shall be disposed of in accordance with B.1.2 b).

5.7.4 Surplus height and burr of weld seam

5.7.4.1 The outer burr of the weld seam of high-frequency welded steel pipe shall be removed to be flush with the base metal. The inner burr shall be fusion welded steel pipe shall not exceed 3 mm. The offset shall be verified by macroscopic examination method. The supplier shall take a weld seam cross-section sample from each lot of steel pipes for macrostructure topography examination.

5.9 Non-destructive testing

5.9.1 Radiographic testing of weld seam

5.9.1.1 The weld seam of electric fusion welded steel pipe shall be subjected to 100% radiographic testing. Radiographic testing shall adopt radiographic shooting testing, radiographic digital imaging testing, or industrial television real-time imaging testing.

5.9.1.2 The radiographic testing of weld seam shall comply with the following regulations:

a) Radiographic film photography shall comply with the requirements of SY/T 6423.1. The image quality level shall be level AB;

b) Radiographic digital imaging testing shall comply with the requirements of SY/T 6423.5. The static image quality level shall be level A;

c) The radiographic industrial television real-time imaging testing shall meet the requirements of GB/T 19293. The dynamic testing sensitivity shall be better than 4%. The testing speed shall be no more than 4.5 m/min or in accordance with the agreement between the supplier and the purchaser;

d) It shall keep the radiographic shooting testing film, or radiographic testing digital image, or industrial television real-time imaging testing image.

5.9.1.3 Unless otherwise stipulated in the contract, radiographic testing acceptance shall be in accordance with SY/T 6423.1.

5.9.2 Ultrasonic testing of weld seam

5.9.2.1 According to the requirements of the purchaser, through negotiation between the supplier and the purchaser, and indicated in the contract, the weld seam of electric fusion welded steel pipe may be longitudinally and transversely ultrasonically tested. The acceptance level shall meet the requirements of U3 or U3H in SY/T 6423.2.

5.9.2.2 The weld seam of high-frequency welded pipe shall be subjected to full-length ultrasonic testing. The acceptance level shall comply with the provisions of U3 or U3H in SY/T 6423.2.

5.9.3 Non-destructive testing of pipe end

The 25 mm width area of each steel pipe end shall be examined for delamination. The testing area shall have no delamination defects with a hoop size greater than 6.0 mm.

5.10 Treatment of defects

5.10.1 The weld seams of high-frequency welded steel pipe and the defects of the base metal shall not be repaired by welding.

5.10.2 The defects of base metal of electric fusion welded steel pipe shall not be repaired by welding. The weld seam may be repaired by welding. The defect treatment method shall comply with the provisions of Appendix B.

6 Test methods

6.1 Sampling for chemical composition analysis of steel pipes shall be carried out in accordance with the rules of GB/T 20066. Chemical composition analysis is usually carried out according to GB/T 4336, GB/T 20123, GB/T 20125, or other common methods. For arbitration, it shall be in accordance with GB/T 223.5, GB/T 223.9, GB/T 223.12, GB/T 223.14, GB/T 223.18, GB/T 223.23,

GB/T 223.25, GB/T 223.26, GB/T 223.40, GB/T 223.58, GB/T 223.62, GB/T 223.68, GB/T 223.84, GB/T 223.86, and GB/T 20125.

6.2 The dimensions and shape of the steel pipe shall be measured one by one using measuring tools or instruments such as a diameter tape measure, a caliper, an optical measuring instrument, etc., which meet the accuracy requirements. The outer diameter of the steel pipe shall be measured at least 50 mm away from the pipe end.

6.3 The inner and outer surfaces of the steel pipe shall be inspected visually or inspected by instrument one by one.

6.4 When the outer diameter of the steel pipe is less than 219.1 mm, for the tensile test of the pipe body, take a longitudinal sample. When the outer diameter of the steel pipe is not less than 219.1 mm, for the tensile test of the pipe body, take a transverse sample.

6.5 Samples for welded joint tensile, welded joint impact, weld seam guided bend, and macroscopic and metallographic examinations may be taken from welding test pieces of the same designation, the same heat number, the same specification, the same welding process, and the same heat treatment system.

6.6 The sampling methods and test methods for other inspection items of steel pipes shall comply with the requirements of Table 8.

7 Inspection rules

7.2 Lot grouping rules

Steel pipes shall be inspected and accepted in lots. Each lot shall consist of steel pipes of the same designation, the same heat number, the same specification, the same welding process, and the same heat treatment system.

When the outer diameter of steel pipe is not more than 219.1 mm, the number of steel pipes per lot shall not exceed 200. When the outer diameter of steel pipe is greater than 219.1 mm, the number of steel pipes per lot shall not exceed 50.

7.3 Sampling quantities

The sampling quantities for each test per lot of steel pipes shall be in accordance with Table 8.

7.4 Re-inspection and decision rules

The re-inspection and decision rules of steel pipes shall comply with the provisions of GB/T 2102.

8 Packing, marking, and quality certification

The packing, marking, and quality certification of steel pipes shall comply with the provisions of GB/T 2102. […]

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 25 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 223.58 · GB/T 3531 · GB/T 19293 · SY/T 6423.1 · SY/T 6423.2

Similar standards

GB/T 13793-2026|GB/T 18984-2026|GB/T 30584-2026|GB/T 3094-2026|GB/T 47090-2026|GB/T 47605-2026

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