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GB/T 14975-2012 English PDF (GBT14975-2012)

GB/T 14975-2012 English PDF (GBT14975-2012)

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GB/T 14975-2012: Seamless stainless steel tubes for structure

This Standard specifies the classification and code, order content, size, shape, weight, technical requirements, test methods, inspection rules, packaging, marks and quality certificate for seamless stainless steel tubes for structure. This Standard is applicable to seamless stainless steel tubes for general structure or mechanical structure
GB/T 14975-2012
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.75
H 48
Replacing GB/T 14975-2002
Seamless stainless steel tubes for structure
ISSUED ON: NOVEMBER 05, 2012
IMPLEMENTED ON: MAY 01, 2013
Issued by: General Administration of Quality Supervision, Inspection and Quarantine;
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 Size, shape and weight ... 8
6 Technical requirements ... 12
7 Test methods ... 22
8 Inspection rules ... 23
9 Packaging, marks and quality certificate ... 24
Annex A (informative) Comparison on stainless steel designation ... 25 Seamless stainless steel tubes for structure
1 Scope
This Standard specifies the classification and code, order content, size, shape, weight, technical requirements, test methods, inspection rules, packaging, marks and quality certificate for seamless stainless steel tubes for structure. This Standard is applicable to seamless stainless steel tubes for general structure or mechanical structure (hereinafter referred to as steel tubes). 2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 222, Permissible tolerances for chemical composition of steel products GB/T 223.9, Iron steel and alloy - Determination of aluminium 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 223.16, Methods for Chemical Analysis of Iron, Steel and Alloy - The Chromotropic Acid Photometric Method for the Determination of Titanium
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 223.28, Methods for chemical analysis of iron, steel and alloy - The ??- benzoin oxime gravimetric method for the determination of molybdenum
GB/T 246, Metallic materials ?€? Tube - Flattening test
GB/T 2102, Acceptance packing marking and quality certification of steel pipe
GB/T 2975, Steel and Steel Products - Location and Preparation of Test
Pieces for Mechanical Testing
GB/T 4334-2008, Corrosion of metals and alloys - Test methods for
intergranular corrosion of stainless steels
GB/T 4340.1, Metallic materials - Vickers hardness test - Part 1: Test method GB/T 5777-2008, Seamless Steel Pipe and Tubing Methods for Ultrasonic
Testing
GB/T 7735-2004, Steel tubes - The Inspection Method on Eddy Current Test GB/T 11170, Stainless steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (Routine method)
GB/T 17395, Dimensions, shapes, masses and tolerances of seamless steel tubes
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
GB/T 20878-2007, Stainless and heat-resisting steels - Designation and
chemical composition
3 Classification and code
3.1 Steel tubes are divided into two categories according to product processing methods. The category and code name are:
- Hot rolled (extruded, expanded) steel tubes W-H;
- Cold drawn (rolled) steel tubes W-C.
3.2 Steel tubes are divided into two levels according to the dimensional 6.1.2 When the purchaser requires finished product analysis, it shall be indicated in the contract. The allowable deviation of the chemical composition of the finished steel tubes shall meet the requirements of GB/T 222.
6.2 Manufacturing method
6.2.1 Steel smelting method
Steel shall be smelted with crude molten steel through external refining method. Agreed by the supplier and the purchaser, other smelting methods may be used. 6.2.2 Manufacturing method of steel tubes
Steel tubes shall be manufactured by hot rolled (extruded, expanded) or cold drawn (rolled) seamless method. Hot-expanded steel tubes shall refer to a larger diameter steel tubes formed by expansion and deformation of the blank steel tubes after being heated as a whole. When the purchaser specifies a certain manufacturing method, it shall be indicated in the contract.
6.3 Delivery status
6.3.1 Steel tubes shall be delivered in a heat-treated and pickled state. All steel tubes that have been integrally ground, bored or heat-treated in a protective atmosphere can be delivered without pickling. Refer to Table 4 for the
recommended heat treatment system for finished steel tubes.
6.3.2 For austenitic hot extruded steel tubes, if the heat treatment temperature range specified in Table 4 is followed by direct water cooling or other rapid cooling, it shall be considered that the heat treatment requirements of steel tubes have been met.
6.3.3 Required by the purchaser, agreed by the supplier and the purchaser and indicated in the contract, austenitic cold drawn (rolled) steel tubes can also be delivered in cold working condition. The curvature, mechanical properties, flattening test shall be negotiated between the supplier and the purchaser. 6.3.4 Agreed by the supplier and the purchaser and indicated in the contract, steel tubes can use other heat treatment systems other than those specified in Table 4.
6.4 Mechanical properties
6.4.1 The longitudinal mechanical properties (tensile strength Rm and
elongation after fracture A) of the heat-treated steel tubes shall meet the requirements of Table 4.
6.4.2 Required by the purchaser, agreed by the supplier and the purchaser and P - The test pressure, in megapascals (MPa), rounded off to the nearest 0.5MPa; S - The nominal wall thickness of steel tubes, in millimeters (mm);
D - The nominal outer diameter of steel tubes, in millimeters (mm);
R - The allowable stress, 60% of the minimum plastic elongation strength specified in Table 4, in megapascals (MPa).
Under the test pressure, the voltage stabilization time shall be no less than 5s, and leakage of the steel tubes is not allowed.
6.6.2 Required by the purchaser, agreed by the supplier and the purchaser and indicated in the contract, other test pressures can be used for hydraulic test. 6.6.3 The supplier can replace the hydraulic test with ultrasonic test or eddy current test. When ultrasonic flaw detection is used, the artificial defects of the comparison sample tube shall meet the requirements of the acceptance level L3 in GB/T 5777-2008. When using eddy current flaw detection, the artificial defect of the control sample tube shall meet the requirements of the acceptance level A in GB/T 7735-2004.
6.7 Intergranular corrosion test
Required by the purchaser, agreed by the supplier and the purchaser and indicated in the contract, austenitic steel tubes can be tested for intergranular corrosion. The intergranular corrosion test method shall meet the requirements of Method E in GB/T 4334-2008. After the test, the specimen is not allowed to show the tendency of intergranular corrosion. Agreed by the supplier and the purchaser and indicated in the contract, other intergranular corrosion test methods can be used.
6.8 Surface quality
6.8.1 The inner and outer surfaces of steel tubes are not allowed to have cracks, folds, folds, delamination and scars. The above defects shall be completely removed. The removal depth shall not exceed 10% of the wall thickness. The actual wall thickness at the place where the defect is removed shall not be less than the minimum allowable wall thickness.
6.8.2 The allowable depth of the straight line on the inner and outer surfaces of the steel tube shall meet the following requirements:
- Hot rolled (extruded, expanded) steel tubes: for steel tubes with a diameter of not more than 5% of the nominal wall thickness and a diameter of not more than 140mm, its maximum allowable depth is 0.5mm; for steel tubes
with a diameter greater than 140mm, the maximum allowable depth is

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