GB/T 46656-2025 Valves for cryogenic vessels
Warning: This document does not purport to address all of the safety issues, if any, associated with the production and application of valves for cryogenic vessels. Before using this document, users are responsible for establishing appropriate safety, health and protection practices, clarifying its scope of application, and ensuring compliance with relevant national laws, regulations, and mandatory national standards.
1 Scope
This document specifies the technical requirements, tests, cleanliness and marking of valves for cryogenic vessels (hereinafter referred to as "valves").
It applies to valves with a rated minimum temperature not higher than -40°C, including the design, manufacture, and inspection of vacuum jacketed cryogenic valves with nominal sizes not greater than DN200. It may be used as a reference for other valves.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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 12220 Industrial valves - Marking (GB/T 12220-2015, ISO 5209-1977, MOD)
GB/T 12224 General requirements for industrial steel valves
GB/T 13927 Industrial valves - Pressure testing (GB/T 13927-2022, ISO 5208:2015, MOD)
GB/T 17213.1 Industrial-process control valves - Part 1: Control valve terminology and general considerations (GB/T 17213.1-2015, IEC 60534-1:2005, IDT)
GB/T 21465 Terminology of valves
GB/T 26479 Fire test for soft-seated quarter-turn valves (GB/T 26479-2011, ISO 10497:2010, MOD)
GB/T 28776 Steel gate, globe and check valve for the petroleum and natural gas industries (for sizes DN100 and smaller) (GB/T 28776-2012, ISO 15761:2002, MOD)
GB/T 31481 Guidance for gas/materials compatibility of cryogenic vessels (GB/T 31481-2015, ISO 21010:2014, IDT)
ISO 11114-1 Gas cylinders - Compatibility of cylinder and valve materials with gas contents - Part 1: Metallic materials
ISO 11114-2 Gas cylinders - Compatibility of cylinder and valve materials with gas contents - Part 2: Non-metallic materials
ISO 21028-1 Cryogenic vessels - Toughness requirements for materials at cryogenic temperature - Part 1: Temperatures below -80°C
ISO 21028-2 Cryogenic vessels - Toughness requirements for materials at cryogenic temperature - Part 2: Temperatures between -80°C and -20°C
ISO 23208 Cryogenic vessels - Cleanliness for cryogenic service
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 21465 and GB/T 17213.1 as well as the following apply.
3.1
maximum allowable working pressure
maximum pressure that the pressure retaining parts of a valve can withstand at a working temperature of 20°C
Note 1: It is the minimum value among the maximum allowable working pressures of all pressure retaining parts of the valve.
Note 2: Vacuum jacketed valves need to take into account the impact of the pressure difference caused by vacuum on the maximum allowable working pressure.
3.2
rated minimum temperature
minimum service temperature of the valve determined by the valve manufacturer
3.3
valve category A
valve type which passed the durability test for 2,000 cycles
3.4
valve category B
valve type which passed the durability test for 100 cycles
4 Technical requirements
4.1 Materials
4.1.1 General
Materials shall be in conformance with the requirements of relevant international standard and industry standard, and compatible with the fluid. Galling, frictional heating and galvanic corrosion shall be considered in the selection of materials. The compatibility of materials with oxygen shall meet the requirements of 4.1.5.1.
Metallic materials that comply with other foreign standards shall be controlled by the manufacturer of the valve by a specification ensuring control of chemical content and physical properties, and ensuring quality at least equivalent to relevant national and industry standards. A test certificate providing the chemical content and physical property test results shall be provided with the valve by the manufacturer of the valve.
4.1.2 Metallic materials
The materials of metallic parts of valves exposed to cryogenic temperature in normal service shall meet the toughness requirements at the rated minimum temperature specified in ISO 21028-1 or ISO 21028-2.
Metallic materials which do not exhibit ductile/brittle transition and non ferrous materials which can be shown to have no ductile/brittle transition do not require cryogenic impact tests.
When the rated minimum temperature is higher than the ductile/brittle transition range temperatures of the material, the parts made of this material need not be cryogenic impact tested if they meet the following conditions:
——Forged, rolled, wrought and fabricated valve parts;
——Casting parts meet the non-destructive testing requirements for forgings, bars, plates or pipes specified in GB/T 12224.
When an impact test is required, at least one randomly selected valve body material (including bonnet, if applicable) from each production-lot casting shall be impact tested at the rated minimum temperature.
4.1.3 Non-metallic materials
Contents
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements
5 Tests
6 Cleanliness
7 Marking
Annex A (Informative) Comparison of clause/subclause numbers
Annex B (Informative) Thermal shock test for valves used in LNG service
Annex C (Informative) Non-toxic gases, refrigerated liquid
Annex D (Informative) Recommended methods for tightness test of cryogenic valves
