GB/T12770-2002 Mechanical Structural Stainless Steel Welded Pipe
This national standard GB/T12770-2002 Mechanical Structural Stainless Steel Welded Pipe is presented by the Standardization Administration of the PRC and the China Metallurgical Industry Association.
This standard supersedes the GB/T12770-1991 mechanical structural stainless steel welded pipe. Compared with the old standard, the main technical changes are that the requirements are put on the pipeline core and the surface, and the mechanical performance indexes are more detailed and perfect.
This standard specifies the size, shape, weight and allowable deviation, technical requirements, test methods, inspection rules and marks, packaging, transportation and storage of mechanical structural stainless steel welded pipes. This standard is applicable to the mechanical structural stainless steel welded pipes whose nominal outer diameter is not more than 114 mm and whose wall thickness is not more than 6 mm.
This national standard refers to the use of relevant national standards and ISO standards. This national standard and the norms of relevant national standards and ISO should be consistent.
The products tested and manufactured by this standard should be in accordance with the rules and regulations of the Peoples Republic of China for measuring and regulating the production process.
Table of Content
1 Scope
2 Normative References
3 Order Content
4 Size, Shape, Weight and Allowable Deviation
5 Technical Requirements
6 Test Methods
7 Inspection Rules
8 Marking, Packaging, Transportation and Storage
1 Scope
This standard specifies the requirements of mechanical structural stainless steel welded pipes (hereinafter referred to as welded pipes) used in construction, industrial and other fields, describes its size, shape, weight and allowable deviation, technical requirements, test method, inspection rules and marking, packaging, transportation and storage.
This standard is applicable to mechanical structural stainless steel welded pipes whose nominal diameter is not more than 114mm and wall thickness is not more than 6mm.
2 Normative References
This standard references the following national standards and international standards:
GB/T222-1984 Permissible Tolerance for Chemical Composition of Steel Products;
GB/T223-1997 Methods for Chemical Analysis of Iron, Steel and Alloy;
GB/T228.1-2003 Metallic Material Tensile Testing Method - Part 1: Room Temperature Test;
GB/T246-1997 Deformation Test Methods of Metallic Materials;
GB/T1184-1993 Lever Arc Welding and Tungsten Arc Welding;
GB/T14981-1994 Methods for Ultrasonic Inspection of Metal Pipe and Fittings;
GB/T14976-2002 Stainless Steel Seamless Steel Pipes;
GB/T12770-1991 Technical Requirements for Welded Pipes of Mechanical Structural Stainless Steel Used for High Pressure Technologies;
GB/T13296-1992 Methods for Sampling Investment Castings;
JB/T4880.1-1999 Welded Steel Fittings Butt Welding End Faces - Part 1: Style A;
JB/T4880.2-1999 Welded Steel Fittings Butt Welding End Faces - Part 2: Style B;
JB/T4736-1995 Inspection of Welded Joints of Steel Structure;
ISO4144-2001 Pipe Threads where Pressure-tight Joints are Made on the Threads.
3 Order Content
In addition to the contents specified in this national standard when placing an order, the page shall include the following items:
a) Name of product, standard number;
b) Steel grade, steel pipe size, wall thickness and length;
c) Application conditions such as manufacturing process, delivery status and products delivery;
d) Delivery time and place;
e) Purpose, use and performance requirements;
f) Relevant requirements of special agreements.
4 Size, Shape, Weight and Allowable Deviation
4.1 Size and shape
The size and shape of the steel pipe should be in accordance with Table 1. The size and shape of stainless steel welded pipes should meet the requirements of drawings and static models.
4.2 The weight and allowable deviation of steel pipes
The weight of steel pipes should be calculated according to the size and shape of steel pipes and the unit stainless steel density of 7.93 g/cm^3. The allowable deviation of the steel pipe weight should meet the requirements of Table 2.
Table 1 Size and Shape of Stainless Steel Welded Pipes
Nominal outer diameter
(mm) 模数
25 3/8
32 1/2
38 3/4
45 1
52 1 1/4
57 1 1/2
63 2
75 2 1/2
88 3
102 4
114 5
Table 2 Allowable Deviation of Pipeline Weight
Nominal outer diameter (mm) Allowable deviation of Weight (%)
25-45 ≤ 10
52-114 ≤ 8
5 Technical Requirements
5.1 Steel grade
The steel grades of stainless steel welded steel pipe should meet the relevant requirements of the Peoples Republic of China gb13296-91 and the requirements of the scope of application of this standard.
5.2 Chemical composition
The chemical composition of stainless steel welded steel pipe should meet the requirements of Table 3.
Table 3 Chemical Composition Requirements of Stainless Steel Welded Pipes
Chemical Component C (≤) Si (≤) Mn P (≤) S (≤)
0Cr19Ni9 0.08 1.00 0.035 0.030
1Cr18Ni9Ti 0.07 1.00 0.035 0.030
0Cr18Ni10Ti 0.08 1.00 0.035 0.030
Test method refers to GB/T223-1997.
5.3 Mechanical properties
The mechanical properties of stainless steel welded pipe should meet the requirements of Table 4.
Table 4 Requirements for Mechanical Properties of Stainless Steel Welded Pipes
Steel grade Tensile Test Region Yield Strength (≥) Tensile Strength (≥) Elongation (%)
0Cr19Ni9 Cold drawing 235 380-540 > 25
Hot rolling 265 410-580 >20
1Cr18Ni9Ti Cold drawing 240 410-550 >25
Hot rolling 280 480-620 >20
0Cr18Ni10Ti Cold drawing 235 380-540 >25
Hot rolling 265 410-580 >20
Test method refers to GB/T228.1-2003.
5.4 Non metallic inclusion
The non-metallic inclusion of stainless steel welded pipe should meet the requirements of Table 5.
Table 5 Non-Metallic Inclusion Requirements of Stainless Steel Welded Pipes
Steel Grade Shape Sizes Contents (%)
0Cr19Ni9
Ampoule shape > 0.8
Flat head shape > 0.6
1Cr18Ni9Ti
Ampoule shape > 1.0
Flat-head shape > 0.8
0Cr18Ni10Ti
Ampoule shape > 0.8
Flat head shape > 0.6
Note:1) The shape of non-metallic inclusions should be characterized mainly by excluding their contents.
2) The determination of non-metallic inclusions shall be performed in accordance with GB/T1184-1993.
5.5 Surface quality
The surface of stainless steel welded pipe should meet the requirements of Table 6.
Table 6 Requirements for Surface Quality of Stainless Steel Welded Pipes
Quality Grade Visual Quality Provisional Adhesive Index
1 No visible depancanization, chapping, cratering, cracks, and other defects, no rust and dirt, partial welding droplets of not more than 1 mm in absolute value, the height shall not exceed 0.2 mm.
2 No visible depression, chapping, cratering, cracks, rust and dirt, less than 5 welding droplets more than 1 mm in absolute value, the height shall not exceed 0.2 mm.
Test method refers to GB/T13296-1992.
5.6 End shape
The end shape of stainless steel welded pipe should meet the requirements of JB/T
