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This standard is developed according to the rules given in GB/T 1.1-2009.
This standard partially replaces GB/T 12459-2005 Steel Butt-welding Seamless Pipe Fittings and GB/T 13401-2005 Steel Plate Butt-welding Pipe Fittings and the following technical changes have been made with respect to GB/T 13401-2005:
——The standard name is modified;
——Contents on relevant technical requirements in GB/T 12459-2005 and GB/T 13401-2005 are incorporated into this standard;
——Material, manufacturing, heat treatment, inspection and test, surface protection and package, product quality certificate and other contents are modified;
——Variety, code, size, tolerance and design verification test and other contents are deleted and are incorporated into GB/T 12459-2017 Steel Buttwelding Pipe Fittings - Types and Parameter;
——Provisions related to order contents, material grade, welding repair and selective additional requirements are added.
This standard was proposed by the China Machinery Industry Federation.
This standard is under the jurisdiction of the National Technical Committee on Pipe Fittings of Standardization Administration of China (SAC/TC 237).
The previous editions of the standard replaced by this standard are as follows:
GB/T 12459-1990, GB/T 12459-2005;
GB/T 13401-1992, GB/T 13401-2005.
Steel Buttwelding Pipe Fittings - Technical Specification
1 Scope
This standard specifies order contents, material, manufacturing, heat treatment, inspections and tests, welding repair, surface protection and package, product quality certificate and other technical requirements of steel butt-welding pipe fittings (hereinafter referred to as pipe fittings).
This standard is applicable to pipe fittings specified in GB/T 12459 and it also can be taken as reference to other pipe fittings.
2 Normative References
The following documents for the application of this standard are essential. For dated references, only the editions cited apply. For undated references, their latest editions (including any amendments) apply.
GB 150.4-2011 Pressure Vessels - Part 4: Fabrication, Inspection and Testing, and Acceptance
GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products
GB/T 223(All Parts) Methods for Chemical Analysis of Iron, Steel and Alloy
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 2975 Steel and Steel Products-Location and Preparation of Test Pieces for Mechanical Testing
GB/T 4334 Corrosion of Metals and Alloys-Test Methods for Intergranular Corrosion of Stainless Steels
GB/T 4336 Standard Test Method for Spark Discharge Atomic Emission Spectrometric Analysis of Carbon and Low-alloy Steel (Routine Method)
GB/T 4338 Metallic Materials- Tensile Testing at Elevated Temperature
GB/T 6394 Metal - Methods for Estimating the Average Grain Size
GB/T 9452 Testing Method for Working Zone of Heat Treatment Furnace
GB/T 10561 Steel - Determination of Content of Nonmetallic Inclusions - Micrographic Method Using Standards Diagrams
GB/T 11170 Stainless Steel - Determination of Multi-element Contents - Spark Discharge Atomic Emission Spectrometric Method (Routine Method)
GB/T 12459-2017 Steel Buttwelding Pipe Fittings - Types and Parameter
GB/T 13305 Micrographic Method for Determining Area Content of the α-phases in Stainless Steels
GB/T 18253-2000 Steel and Steel Products - Types of Inspection Documents
GB/T 20801.2 Pressure Piping Code - Industrial Piping - Part 2: Materials
NB/T 47013.2 Nondestructive Testing of Pressure Equipments - Part 2: Radiographic Testing
NB/T 47013.3 Nondestructive Testing of Pressure Equipments - Part 3: Ultrasonic Testing
NB/T 47013.4 Nondestructive Testing of Pressure Equipments - Part 4:Magnetic Particle Testing
NB/T 47013.5 Nondestructive Testing of Pressure Equipments - Part 5: Penetrant Testing
NB/T 47014 Welding Procedure Qualification for Pressure Equipment
NB/T 47015 Welding Specification for Pressure Vessels
TSG Z6002 Examination Rules for Welding Operators of Special Equipment
TSG Z8001 Examination Rules for Special Equipment Non-destructive Testing Inspectors
3 Order Contents
The purchaser shall provide the following information required for pipe fittings to be purchased in orders:
a) Variety or code;
b) Material grade (see 4.2);
c) Nominal size (standard or designated; "-II" shall be marked where series II outside diameter in GB/T 12459 is selected) and nominal wall thickness (see 4.2.2, GB/T 12459-2017);
d) Structure (seamless or welded; if not specified, either one shall be selected by the pipe fitting manufacturer);
e) Product standard No.: GB/T 12459 and GB/T 13401 (including version No.);
f) Number of pieces;
g) Necessary additional requirements (see Annex A) or supplementary provisions.
4 Materials
4.1 Materials for manufacturing pipe fittings include seamless pipe, longitudinal electrofusion welded pipe, plates, bars and forgings and their chemical composition shall meet the requirements of Table 1. They shall be also subjected to chemical composition analysis one per smelting furnace No. in method meeting the requirements of GB/T 223 or GB/T 4336 and GB/T 11170 to ensure their compliance with the requirements of Table 1. Besides, permissible deviation of chemical composition shall meet the requirements of GB/T 222 during such product analysis.
4.2 Grade code for pipe fitting materials stands for:
a) CF is the abbreviation of carbon steel fitting; the following numbers are the minimum tensile strength of the pipe fittings; the suffix letter K represents that this grade shall pass 20℃ impact test.
b) AF is the abbreviation of alloy steel fitting; the following numbers adopt familiar characteristic number in the industry; the suffix letter G represents this grade has higher tensile property.
c) LF is the abbreviation of low temperature steel fitting; the following numbers represent the minimum tensile strength of the pipe fittings; the suffix letters K1, K2, K3 and K4 represent the minimum service temperature of -20℃, -46℃, -100℃ and -196℃ respectively.
d) SF is the abbreviation of stainless steel fitting; the following numbers adopt familiar characteristic number in the industry; the suffix letters L and H represent lower and higher carbon element content.
4.3 See Annex B for common materials for manufacturing pipe fittings. Although raw materials other than those in Annex B are not restricted for use, the materials used shall meet the requirements of GB/T 20801.2 or relevant specifications and structural steel pipes shall not be used for manufacturing pipe fittings.
4.4 The welding materials adopted by welded pipe fittings manufactured with plates shall be selected according to NB/T 47015 or relevant specifications. For stainless steel welded pipe fittings, their weld metal shall be subjected to chemical composition analysis once per welding materials batch No.
4.5 Austenitic stainless steel fittings may be ordered and/or supplied according to two-symbol material grade in SF304/SF304L, SF304/SF304H, SF316/SF316L, SF316/SF316H, SF321/SF321H and SF347H. Under such cases, pipe fittings shall meet the requirements of chemical composition and mechanical properties for each material grade.
5 Manufacture
5.1 Pipe fittings may be manufactured by one or combination of such methods as extrusion, pushing, mould pressing, pull-out, forging, welding or cutting processing
5.2 Hollow cylindrical pipe fittings less than or equal to DN100 may be directly machined with bars and their axial direction shall be approximately parallel with metal fiber direction of relevant materials; elbow, tee and cross shall not be directly subjected to cutting processing with bars.
5.3 Welded pipe fittings welded and manufactured by pipe fitting manufacturer shall meet the following conditions:
a) Welding procedure qualification is conducted according to NB/T 47014 or relevant specification;
b) Welding procedure specification is formulated according to NB/T 47015 or relevant specifications;
c) All welding works are completed by welder passing the examination and acquiring corresponding welding qualification according to TSG Z6002 or relevant specifications according to welding procedure specification;
Foreword i
1 Scope
2 Normative References
3 Order Contents
4 Materials
5 Manufacture
6 Heat Treatment
7 Inspections and Tests
7.1 Mechanical Properties
7.1.1 Mechanical Property Specimen
7.1.2 Tensile Test
7.1.3 Impact Test
7.1.4 Hardness Test
7.1.5 Repeated Heat Treatment
7.2 Shape, Size and Appearance
7.3 Nondestructive Testing
7.4 Metallographic Inspection
7.5 Hydrostatic Test
7.6 Summary of Inspections and Tests
8 Welding Repair
9 Surface Protection and Package
10 Product Quality Certificate
Annex A (Normative) Additional Requirements
Annex B (Informative) Raw Materials for Pipe Fittings