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GB/T 12771-2019 (GB/T12771-2019)

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GB/T 12771-2019: PDF in English (GBT 12771-2019)
GB/T 12771-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.75
H 48
Replacing GB/T 12771-2008
Welded Stainless Steel Pipes for Fluid Transport
ISSUED ON: OCTOBER 18, 2019
IMPLEMENTED ON: SEPTEMBER 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative References ... 5 
3 Classification and Code ... 7 
4 Order Content ... 8 
5 Dimensions, Appearance and Weight ... 8 
6 Technical Requirements ... 12 
7 Test Methods ... 20 
8 Inspection Rules ... 21 
9 Packaging, Marking and Quality Certificate ... 22 
Welded Stainless Steel Pipes for Fluid Transport
1 Scope
This Standard stipulates the classification, code, order content, dimensions,
appearance and weight, technical requirements, test methods, inspection rules,
packaging, marking and quality certificate of welded stainless steel pipes for fluid
transport.
This Standard is applicable to welded stainless steel pipes for fluid transport
(hereinafter referred to as steel pipes).
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products;
GB/T 223.9 Iron, Steel and Alloy - Determination of Aluminum Content - Chrome Azurol
S Photometric Method;
GB/T 223.11 Iron, Steel and Alloy - Determination of Chromium Content - Visual
Titration or Potentiometric Titration Method;
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 223.19 Methods for Chemical Analysis of Iron, Steel and Alloy - The Neocuproine
Chloroform Extraction Photometric 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 223.28 Methods for Chemical Analysis of Iron, Steel and Alloy - The -
benzoinoxime Gravimetric Method for the Determination of Molybdenum Content;
GB/T 223.36 Methods for Chemical Analysis of Iron, Steel and Alloy - The Neutral
Titration Method for the Determination of Nitrogen Content after Distillation Separation;
GB/T 223.37 Methods for Chemical Analysis of Iron, Steel and Alloy - The Indophenol
Blue Photometric Method for the Determination of Nitrogen Content after Distillation
Separation;
GB/T 223.40 Iron, Steel and Alloy - Determination of Niobium Content by the
Sulphochlorophenol S Spectrophotometric Method;
GB/T 223.59 Iron, Steel and Alloy - Determination of Phosphorus Content - Bismuth
Phosphomolybdate Blue Spectrophotometric Method and Antimony
Phosphomolybdate Blue Spectrophotometric Method;
GB/T 223.60 Methods for Chemical Analysis of Iron, Steel and Alloy - The Perchloric
Acid Dehydration Gravimetric Method for the Determination of Silicon Content;
GB/T 223.63 Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium
(potassium) Periodate Photometric Method for the Determination of Manganese
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 223.69 Iron, Steel and Alloy - Determination of Carbon Contents - Gas-volumetric
Method after Combustion in the Pipe Furnace;
GB/T 223.84 Steel and Iron - Determination of Titanium Content - Diantipyrylmethane
Spectrophotometric Method;
GB/T 223.85 Steel and Iron - Determination of Sulfur Content - Infrared Absorption
Method after Combustion in an Induction Furnace;
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 241 Metal Materials - Tubes - Hydrostatic Pressure Test;
GB/T 245 Metallic Materials -Tube - Flanging Test;
GB/T 246 Metallic Materials -Tube - Flattening Test;
GB/T 2102 Acceptance, Packing, Marking and Quality Certification of Steel Pipe;
welding; welding seam receives 100% full-length radiographic inspection;
c) III---steel pipes are manufactured through the method of double-sided automatic
welding; welding seam receives partial radiographic inspection;
d) IV---steel pipes are manufactured through the method of single-sided automatic
welding; welding seam receives partial radiographic inspection;
e) V---steel pipes are manufactured through the method of double-sided automatic
welding; welding seam does not receive radiographic inspection;
f) VI---steel pipes are manufactured through the method of single-sided automatic
welding; welding seam does not receive radiographic inspection.
3.2 In accordance with delivery status, the classification and code of steel pipes are as
follows:
a) Status of welding +H;
b) Status of thermal treatment +T;
c) Status of grinding (polishing) +SP.
4 Order Content
Contract or order form that purchase steel pipes in accordance with this Standard shall
include the following content:
a) Serial No. of this Standard;
b) Product name;
c) Steel designation;
d) Dimensions and specifications (external diameter  wall thickness, expressed
in millimeter);
e) Quantity ordered (total weight or total length);
f) Delivery status;
g) Special requirements.
5 Dimensions, Appearance and Weight
5.1 External Diameter and Wall Thickness
with the stipulations in Table 4. However, in arbitration, longitudinal tensile test shall be
subject to.
6.4.2 Tensile test of welded joints
Steel pipes whose external diameter is not less than 168 mm shall receive horizontal
tensile test on welded joints. Samples shall be horizontally taken along the steel pipes,
or, be cut out from test pieces of welding. The test pieces of welding shall be under the
same designation, the same furnace No., the same welding process and the same
thermal treatment system as the steel pipes. Welding seam shall be in the center of
the sample and vertical to the axes of the sample. The tensile strength of welded joints
shall comply with the stipulations of tensile strength of base metals in Table 4.
6.5 Process Performance
6.5.1 Flattening
Steel pipes whose external diameter is not more than 168 mm shall receive flattening
test. During the test, welding seam shall be located in a location that is 90 of the force-
bearing direction. In terms of steel pipes which receive thermal treatment, samples
shall be flattened to 1/3 of the external diameter of steel pipes. In terms of steel pipes
which do not receive thermal treatment, samples shall be flattened to 2/3 of the
external diameter of steel pipes. After flattening, samples shall not manifest any cracks
or breakages.
6.5.2 Horizontal bending test of welding seam
Steel pipes whose external diameter is more than 168 mm shall receive horizontal
bending test of welding seam. Samples for the bending test shall be cut out from steel
pipes or test pieces of welding. The test pieces of welding shall be under the same
designation, the same furnace No., the same welding process and the same thermal
treatment system as the steel pipes. A group of bending tests shall include: one positive
bending test and one negative bending test (namely, the external welding seam and
the internal welding seam of steel pipes are respectively located on the maximum
curved surface). In terms of steel pipes whose wall thickness is more than 10 mm, two
side bending samples may be used to replace positive bending and negative bending
samples. In bending test, the diameter of bent indenter shall be 4 times of the thickness
of the samples; bending angle shall be 180. After bending, the welding seam area of
the samples shall not manifest any cracks or breakages.
6.6 Intergranular Corrosion
Except from designations ,
the remaining Austenitic stainless steel pipes shall receive intergranular corrosion test
in accordance with the stipulations of Method E in GB/T 4334-2008. After the test,
samples shall not manifest tendency of intergranular corrosion. In accordance with the
demand-side’s demands, through the negotiation between the demand-side and the
pipes under the designations
may receive grain size test; the average grain size shall be Level-7 or coarser.
6.9 Nondestructive Testing
6.9.1 In accordance with the demand-side’s demands, through the negotiation
between the demand-side and the supply-side, and statement in the contract, steel
pipes may receive full-length or partial radiographic inspection of welding seam. When
it is stipulated in the contract that partial radiographic inspection shall be conducted,
the proportion and the location (it shall at least include two pipe ends) of the inspection
shall be indicated.
6.9.2 Radiographic inspection may be conducted and determined through the method
of photographic film or real-time imaging as stipulated in GB/T 3323, NB/T 47013.2 or
NB/T 47013.11. The grade of radiographic testing technology shall comply with the
stipulations of Grade-AB in NB/T 47013.2 or NB/T 47013.11, or the stipulations of
Grade-A in GB/T 3323. The result evaluation and quality grade of 100% radiographic
inspection and partial radiographic inspection shall comply with the stipulations in GB/T
3323 or Grade-II in NB/T 47013.2.
6.9.3 Through the negotiation between the demand-side and the supply-side, and
statement in the contract, other inspection technology grades and/or quality grades
may also be stipulated.
6.9.4 Radiographic inspection may be conducted before thermal treatment.
6.10 Surface Quality
6.10.1 The internal and external surface of steel pipes shall be smooth; there shall be
no defects of stratification, crack, unthorough welding, unthorough fusion, folding,
double skin, twisting, over-pickling and other defects that would affect the usage. The
above-mentioned defects shall be completely eliminated. The actual wall thickness of
the elimination area shall be not less than the allowable minimum value of nominal wall
thickness. The surface of steel pipes may allow the existence of partial scratches and
indentations, but the depth shall not exceed 50% of the lower deviation of wall
thickness; those that exceed this value may allowed to be polished, and the actual wall
thickness of the polishing area shall be not less than the allowable minimum value of
nominal wall thickness.
6.10.2 In terms of steel pipes which are manufactured through the method of double-
sided automatic welding, the internal and external welding seam shall be flush with the
base metals, or, have a uniform surplus height of less than 3 mm.
6.10.3 In terms of steel pipes which are manufactured through the method of single-
sided automatic welding, the external welding seam shall be flush with the base metals,
or, have a uniform surplus height of less than 3 mm; the surplus height of the internal
welding seam shall comply with the following stipulations:
The inspection and acceptance inspection of steel pipes shall be conducted by the
supply-side’s quality and technology supervision department.
8.2 Batch Rules
The chemical composition of steel pipes may be inspected and accepted in
accordance with furnace. The remaining inspection items of steel pipes shall be
inspected and accepted in accordance with batch. Each batch shall be constituted of
steel pipes of the same designation, the same furnace No., the same dimensions, the
same welding process and the same thermal treatment system. The quantity of each
batch of steel pipes shall not exceed the following stipulations:
a) External diameter is not more than 57 mm: 400 PCS;
b) External diameter is more than 57 mm, but not more than 219 mm: 200 PCS;
c) External diameter is more than 219 mm: 100 PCS.
8.3 Sampling Quantity
The sampling quantity of steel pipes for each inspection item shall comply with the
stipulations in Table 5.
8.4 Re-inspection and Determination Rules
Re-inspection and determination rules of steel pipes shall comply with the stipulations
in GB/T 2102.
9 Packaging, Marking and Quality Certificate
9.1 The marking of steel pipes shall include the code, which is classified in accordance
with manufacturing method and radiographic testing. The remaining requirements shall
comply with the stipulations in GB/T 2102. Example 1 and Example 2 provide marking
examples of steel pipes.
Example 1: nominal external diameter 508 mm; wall thickness 8.0 mm; length 6,000 mm;
designation 06Cr19Ni10; manufacturing method Type-I steel pipes, shall be
marked as:
Example 2: nominal external diameter 159 mm; wall thickness 3.0 mm; length 6,000 mm;
designation 07Cr18Ni11Nb; manufacturing method Type-IV steel pipes, have
received stabilized thermal treatment, shall be marked as:
......
 
(Above excerpt was released on 2019-11-16, modified on 2021-06-07, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT12771-2019