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GB/T 21833.2-2020 English PDF (GBT21833.2-2020)

GB/T 21833.2-2020 English PDF (GBT21833.2-2020)

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GB/T 21833.2-2020: Seamless austenitic-ferritic (duplex) stainless steel tubes and pipes -- Part 2: Pipes for fluid service

This Part of GB/T 21833 specifies the order content, dimensions, shapes, masses, technical requirements, test methods, inspection rules, packing, marking, and quality certification of seamless austenitic-ferritic (duplex) stainless steel tubes and pipes for fluid service.
GB/T 21833.2-2020
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.75
H 48
Partially replacing GB/T 21833-2008
Seamless austenitic-ferritic (duplex) stainless steel
tubes and pipes - Part 2: Pipes for fluid service
ISSUED ON: APRIL 28, 2020
IMPLEMENTED ON: NOVEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Order content ... 7
4 Dimensions, shapes, and masses ... 8
5 Technical requirements ... 10
6 Test methods ... 16
7 Inspection rules ... 17
8 Packing, marking, and quality certification ... 18
Appendix A (Informative) High-temperature mechanical properties of some designations ... 19
Seamless austenitic-ferritic (duplex) stainless steel
tubes and pipes - Part 2: Pipes for fluid service
1 Scope
This Part of GB/T 21833 specifies the order content, dimensions, shapes, masses, technical requirements, test methods, inspection rules, packing, marking, and quality certification of seamless austenitic-ferritic (duplex) stainless steel tubes and pipes for fluid service.
This Part applies to seamless austenitic-ferritic (duplex) stainless steel tubes and pipes for fluid service (hereinafter referred to as steel pipes).
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 223.11 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 iodometric 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 223.25 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 ??- benzoin oxime gravimetric method for the determination of molybdenum
content
GB/T 4334-2020 Corrosion of metals and alloys - Test methods for
intergranular corrosion of austenitic and ferritic-austenitic (duplex) stainless steels
GB/T 5777-2019 Automated full peripheral ultrasonic testing of seamless and welded (except submerged arc-welded) steel tubes for the detection of
longitudinal and/or transverse imperfections
GB/T 7735-2016 Automated eddy current testing of seamless and welded
(except submerged arc-welded) steel tubes for detection of imperfections GB/T 11170 Stainless steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (Routine method)
GB/T 13305 Micrographic method for determining area content of the ??-
phases in stainless steels
GB/T 17395 Dimensions, shapes, masses and tolerances of seamless steel
tubes
GB/T 17897 Corrosion of metals and alloys - Corrosion test for pitting
corrosion resistance of stainless steels in the ferric chloride solution 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 20124 Steel and iron - Determination of nitrogen content - Thermal conductimetric method after fusion in a current of inert gas (routine method) 3 Order content
The contract or order for ordering in accordance with this Part shall include the following:
a) Number of this Part;
b) Product name;
c) Steel designation;
d) Dimensions and specifications (outer diameter and wall thickness);
e) Quantity ordered (total mass or total length);
4.2 Length
4.2.1 Normal length
The normal length of the steel pipes is 3000 mm~12000 mm. According to the requirements of the purchaser, through negotiation between the supplier and the purchaser, and indicated in the contract, steel pipes of other lengths can be supplied.
4.2.2 Fixed length and multiple length
According to the requirements of the purchaser, through negotiation between the supplier and the purchaser, and indicated in the contract, steel pipes with fixed length, multiple length, or other specific length requirements can be supplied. The total fixed length and multiple length shall be within the normal length range. The tolerance of the total length is mm. For steel pipes
delivered in multiple lengths, the cut margin shall be 5 mm~10 mm for each cut. 4.3 Bending
The bending of each meter of the steel pipe shall meet the following
requirements:
a) When S???15 mm, it is not more than 1.5 mm/m;
b) When S>15 mm, it is not more than 2.0 mm/m.
4.4 Out-of-roundness and uneven wall thickness
The out-of-roundness and uneven wall thickness of the steel pipes shall not exceed 80% of the tolerances of the outer diameter and wall thickness,
respectively.
4.5 End shape
The end faces of both ends of the steel pipe shall be perpendicular to the axis of the steel pipe. It shall remove the cut burrs.
4.6 Masses
Steel pipes are delivered according to actual mass; can also be delivered according to theoretical mass. The theoretical mass of the steel pipe per meter is calculated according to formula (1).
Where:
5.2 Manufacturing method
5.2.1 Smelting method of steel
Steel shall be smelted by electric arc furnace plus external refining or converter plus external refining or electroslag remelting process. Through negotiation between the supplier and the purchaser, and indicated in the contract, other smelting methods can also be used.
5.2.2 Manufacturing method of steel pipe
The steel pipes shall be manufactured by hot-rolling (hot-extrusion) or cold- drawing (rolling) seamless production process.
5.3 Delivery state
5.3.1 Steel pipes shall be delivered after heat treatment and pickling. Steel pipes, which have been heat-treated in a protective atmosphere or ground (polished) as a whole, can be delivered without pickling.
5.3.2 See Table 3 for the recommended heat treatment system for steel pipes. Through negotiation between the supplier and the purchaser, and indicated in the contract, heat treatment systems other than Table 3 can be used for steel pipes.
5.4 Mechanical properties
5.4.1 The longitudinal mechanical properties of steel pipes delivered in heat- treated state shall comply with the requirements of Table 3.
5.4.2 Steel pipes with a wall thickness of not less than 1.7 mm shall be tested for Brinell or Rockwell hardness. Their values shall comply with the
requirements of Table 3.
5.4.3 According to the requirements of the purchaser, through negotiation between the supplier and the purchaser, and indicated in the contract, the steel pipes can be subjected to an impact test. The test temperature and impact absorbed energy are negotiated between the supplier and the purchaser.
5.5 Hydrostatic pressure
5.5.1 Steel pipes shall be subjected to hydrostatic pressure test one by one. The test pressure is calculated according to formula (2). The maximum test pressure is 20 MPa. Under the test pressure, the pressure stabilization time shall be no less than 10 s. The steel pipe shall not leak.
Where:
P - Test pressure, in megapascals (MPa);
S - The nominal wall thickness of the steel pipe, in millimeters (mm);
R - Allowable stress. It is 50% of the minimum Rp0.2 value specified in Table 3, in megapascals (MPa);
D - The nominal outer diameter of the steel pipe, in millimeters (mm).
5.5.2 The supplier can replace the hydrostatic pressure test with eddy current testing. During eddy current testing, the artificial defects of the comparative sample pipe shall comply with the provisions of the acceptance level E4H or E4 in GB/T 7735-2016.
5.6 Flattening
Steel pipes with a wall thickness not greater than 10 mm shall be subjected to flattening test. After flattening, the spacing H between two parallel pressing plates is calculated according to formula (3). After the sample is flattened, there shall be no cracks or gaps.
Where:
H - The distance between parallel pressing plates after flattening, in millimeters (mm);
?? - Deformation coefficient per unit length, 0.07;
S - The nominal wall thickness of the steel pipe, in millimeters (mm);
D - The nominal outer diameter of the steel pipe, in millimeters (mm).
5.7 Drift-expending
There shall be no cracks, folds, rolled folds, delamination, and scars on the inner and outer surfaces of the steel pipe. These defects shall be completely removed. The removal depth shall not exceed the lower tolerance of the
nominal wall thickness. The actual wall thickness at the removal location shall not be less than the allowable minimum wall thickness. Other local defects not exceeding the lower tolerance of wall thickness are allowed.
5.13 Special requirements
When the purchaser has the following special requirements, the supplier and the purchaser shall negotiate and indicate in the contract:
a) Adjust the chemical composition range specified in Table 2;
b) Provide modulus of elasticity and thermal expansion coefficient data; c) Test of harmful precipitating phase;
d) Provide the measured data of high-temperature mechanical properties. For recommended high-temperature mechanical property values of some
designations, see Appendix A;
e) Specify the content of austenite or ferrite different from the requirements of 5.8;
f) Other requirements.
6 Test methods
6.1 Sampling for chemical composition analysis of steel pipes shall be carried out according to the rules of GB/T 20066. The chemical composition analysis is usually carried out according to GB/T 11170, GB/T 20123, GB/T 20124, or other general methods. During arbitration, it shall be carried out according to the provisions of GB/T 223.11, GB/T 223.18, GB/T 223.19, GB/T 223.25, GB/T
223.26, GB/T 223.28, GB/T 223.36, GB/T 223.43, GB/T 223.59, GB/T 223.60, GB/T 223.84, GB/T 223.85, and GB/T 223.86.
6.2 The dimensions and shapes of the steel pipes shall be measured one by one using a measuring tool, which meets the accuracy requirements.
6.3 The inner and outer surfaces of the steel pipes shall be visually inspected one by one under sufficient lighting conditions.
6.4 The sampling methods and test methods for other inspection items of steel pipes shall comply with the provisions of Table 5.

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