GB/T 12228-2025 General purpose industrial valves - Technical specification for carbon steel forgings English, Anglais, Englisch, Inglés, えいご
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ICS 13.220.10
CCS H 57
National Standard of the People's Republic of China
GB/T 12228-2025
Replaces GB/T 12228-2006
General purpose industrial valves - Technical specification for carbon steel forgings
通用阀门 碳素钢锻件技术规范
Issue date: 2025-10-31 Implementation date: 2026-05-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Technical Requirements
4.1 General Requirements
4.2 Forging
4.3 Heat Treatment
4.4 Chemical Composition
4.5 Mechanical Properties
4.6 Quality Requirements
4.7 Forging Grade
4.8 Metallographic Examination
4.9 Non-destructive Testing
5 Test Methods
5.1 Chemical Analysis
5.2 Tensile Test
5.3 Hardness Test
5.4 Impact Test
5.5 Metallographic Examination
5.6 Non-destructive Testing
6 Inspection Rules
7 Order Requirements
8 Marking and Quality Certificate
Table 1 Heat Treatment Methods and Temperatures
Table 2 Chemical Composition
Table 3 Mechanical Properties
Table 4 Standard Size Specimen (10 mm × 10 mm) Charpy V-notch Impact Energy Requirements
Table 5 Forging Inspection Items
1 Scope
This document specifies the technical requirements, test methods, inspection rules, order requirements, and marks and quality certificates for carbon steel forging used in general valves. This document is applicable to the design, production, and inspection of pressure-bearing carbon steel forgings for general valves. Other carbon steel forgings may refer to this document.
2 Normative Referenced Documents
The following documents contain provisions that form an integral part of this document. For documents with a publication date, only the version published on that date is applicable. For documents without a publication date, the latest version (including all amendments) is applicable.
3 Terms and Definitions
This document does not require the definition of terms and definitions.
4 Technical Requirements
4.1 General Requirements
Carbon steel forgings (hereinafter referred to as "forgings") may use materials of grades 20, 25, 35, A105, LF2, and LF6.
4.2 Forging
4.2.1 The steel used for forging should be made by electric furnace or oxygen converter steelmaking and refined outside the furnace to obtain killed steel.
4.2.2 The ingot should have sufficient head to prevent shrinkage cavities, segregation, folding, and other harmful defects.
4.2.3 Forging should meet the full deformation of the forging to meet the drawing and technical requirements.
4.2.4 During forging, the forging should be slowly cooled through the phase transformation temperature range.
4.2.5 After the forging is finally shaped, it should be cooled to below 500°C before undergoing the specified heat treatment.
4.2.6 When forging with ingots, billets, or continuous casting billets, the forging ratio of the main cross-sectional part of the forging should not be less than 3. When forging with rolled material, the forging ratio of the main cross-sectional part of the forging should not be less than 1.6.
4.3 Heat Treatment
4.3.1 The forging should undergo heat treatment.
4.3.2 The heat treatment method for the forging shall be in accordance with Table 1. The heat treatment status code is: N— annealing, Q— quenching, T— tempering. If the forging has been quenched and tempered, the letters "QT" should be printed after the material code of the forging.
4.3.3 The heat treatment temperature for the forging can refer to Table 1.
4.5.3 Room temperature mechanical property test samples should be taken from the finished forging or representative forging billet, but the forging billet should use approximately the same processing technology as the product and undergo heat treatment together with the forging.
4.5.4 The method of taking mechanical property test blocks should comply with the provisions of NB/T 47008, and the sampling positions are as follows:
a) Directly on the part;
b) On the extended part of the forging;
c) Making billets of the same cross-sectional shape.
4.6 Quality Requirements
4.6.1 The shape and dimensions of the forging should meet the requirements of the order drawing.
4.6.2 The surface quality of the forging should be good, with no visible cracks, folds, pits, inclusions, and other harmful defects to the naked eye.
4.6.3 Defects in the forging that extend to the limit size of the forging are harmful defects and should be scrapped.
4.6.4 Defects in the forging that do not extend to the limit size of the forging and can be removed by mechanical processing or grinding are non-harmful defects and can be handled as follows:
a) Folds with a depth not exceeding 5% of the limit size or 1.5 mm (whichever is smaller) do not need to be removed. If the defect needs to be removed, mechanical processing or grinding should be used.
4.8 Microstructure Examination
According to the requirements of the supply and demand contract, the forging can undergo microstructure examination. The inspection items (grain size, non-metallic inclusions, microstructure, etc.) and the qualified grade of the forging are determined by negotiation between the supply and demand parties.
4.9 Non-destructive Testing
4.9.1 According to the forging grade required by the supply and demand contract, the forging should be subjected to ultrasonic testing in accordance with Table 5.
4.9.2 According to the requirements of the supply and demand contract, the surface of the forging can be inspected using methods such as magnetic particle or liquid penetrant testing.
5 Test Methods
5.1 Chemical Analysis
Chemical analysis shall be carried out in accordance with GB/T 223 (all parts), GB/T 4336, and GB/T 20123.
5.2 Tensile Test
5.2.1 Each batch of heat-treated forgings should undergo one tensile test. If the batch of heat-treated forgings includes two or more material melting furnace numbers, a tensile test should be conducted for each melting furnace number.
5.2.2 The room temperature tensile test method shall be carried out in accordance with GB/T 228.1.
5.2.3 If the forging is too small to take the minimum test block for tensile testing or cannot cut a test block parallel to the main deformation direction, or cannot forge a test block on the equipment, then 1% or 10 pieces (whichever is smaller) of the batch can be taken for hardness testing.
5.3 Hardness Test
The hardness test of the forging shall be carried out in accordance with GB/T 231.1.
