GB/T 45027-2024Valves for liquid hydrogen - General specification (English PDF)

1 Scope

GB/T 45027-2024 is the Chinese general specification for liquid hydrogen valves. At minus 253 degrees Celsius almost nothing behaves as it does at room temperature: elastomers are useless, most steels are brittle, the metal contracts enough to change every clearance, and hydrogen itself is small enough to leak through what would stop any other gas. A liquid hydrogen valve is therefore a distinct engineering object, not a cryogenic valve with a different label. The standard sets the classification and designation, the requirements on the materials at cryogenic temperature, the design and structural requirements including the extended bonnet and the vacuum jacket, the requirements on the seat and stem sealing and on leak tightness in both directions, the pressure and temperature ratings, the flow characteristics, the cleanliness requirements for hydrogen service, the operating torque and endurance, the test methods including the cryogenic and helium leak tests, the inspection rules and the marking, packaging, transport and storage. For a valve maker, a hydrogen plant builder or an operator in China, this is the acceptance text.

This document specifies the technical requirements, test methods, inspection rules, marking, packaging, storage and transportation requirements for valves for liquid hydrogen (hereinafter referred to as "valves"). This document is applicable to globe valves, check valves, ball valves, pneumatic control valves and fusible cut-off emergency shut-off valves for liquid hydrogen with nominal pressure not exceeding PN160, pressure grade not exceeding Class900, insulated by vacuum jacket and connected by welding.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document.

GB/T 150.4, Pressure vessels - Part

3 Terms and definitions

Terms and definitions determined by GB/T 21465 and the following ones are applicable to this document.

3.1 maximum allowable working pressure The maximum pressure that the valve pressure-bearing parts are allowed to withstand when the medium temperature is -20 °C ~ 38 °C.

Note. The maximum allowable working pressure is the lowest value among the maximum allowable working pressures of all pressure-bearing parts of the valve.

3.2 rated minimum temperature The minimum operating temperature of the valve.

3.3 body extension The valve body structure that is appropriately lengthened between the connection end of the valve body and the valve cover.

5 Test methods

Warning When conducting pressure tests, it is necessary to evaluate the safety of the test gas or liquid pressure and the emission of hydrogen; when conducting low-temperature performance tests, it is necessary to evaluate the safety of the test medium, test system, test environment, and the safety protection of the test operators.

6 Inspection rules

6.1 Factory inspection Valves shall be inspected one by one before leaving the factory and can only leave the factory after passing the inspection. Factory inspection items shall comply with the requirements of Table 11.

7 Marking

7.1 General requirements Valves shall be marked in accordance with the provisions of GB/T 12220 and shall comply with the provisions of this document. The valve nameplate material shall be austenitic stainless steel.

7.2 Markings on the valve body The valve body shall include at least the following.

7.3 Markings on the plate The valve plate shall include at least the following.

8 Packaging, storage and transportation

8.1 Except for the drive unit, the inner and outer surfaces of the valve shall not be painted or sprayed with any anti-rust layer.

8.2 After the inspection and test, the inside of the valve shall be kept free of oil, debris and dry. The entire valve shall be sealed and packed, and nitrogen protection should be used.

8.4 The packaging site shall be clean and dry. Appropriate protective measures shall be taken during packaging. Valves shall not come into contact with bare hands or unclean objects, and shall be prevented from iron ion contamination.