Chinese Cryogenic & Fire-Safe Valve Standards: GB/T 24925, GB/T 26479 vs BS 6364, API 607

Cryogenic Valves: GB/T 24925

For LNG, air separation and other low-temperature services, the governing Chinese standard is GB/T 24925, "Cryogenic valves - Technical specifications" (低温阀门 技术条件). Its scope is media temperatures from -196 deg C to -29 deg C, nominal pressures PN16 to PN400 (and Class 150 to 2500), and nominal sizes DN15 to DN1200 (NPS 1/2 to 48). It covers gate, globe, check, ball and butterfly valves.

Internationally, the closest counterparts are BS 6364 (UK, long the de-facto LNG industry reference) and ISO 28921 (isolating valves for low-temperature applications). GB/T 24925 sits in the same technical family: extended bonnet, low-temperature material selection, and cryogenic performance testing.

Extended Bonnet: 200 mm vs 250 mm

Both standards mandate an extended (long-neck) bonnet so the packing stays near ambient temperature and does not freeze or lose seal force. The minimum lengths differ:

• GB/T 24925: minimum extended-bonnet length 200 mm
• BS 6364: minimum 250 mm (non-cold-box applications)

This 50 mm difference matters when insulation thickness is specified. A Chinese cryogenic valve built to GB/T 24925 may have a shorter neck than a BS 6364 valve, and the packing may sit closer to the cold zone once insulation is applied. Verify the as-built bonnet length against your insulation detail rather than assuming interchangeability.

Cryogenic Treatment and Fugitive Emissions

The 2019 revision of GB/T 24925 added two requirements that international buyers should check for:

1. Mandatory cryogenic treatment for austenitic stainless steel valves used below -100 deg C. This stabilises the microstructure (preventing martensitic transformation and the associated sealing-surface deformation) before finish machining.
2. Fugitive emission limits of 100 ppmv for stem and body-bonnet joints, reflecting tightening global emissions expectations.

Material selection follows the usual低温 logic: -46 deg C duties use low-temperature carbon steel; -101 deg C and below use 300-series austenitic stainless (06Cr19Ni10 / CF8). The Chinese valve material grade cross-reference maps these grades to ASTM equivalents.

Fire-Safe Testing: GB/T 26479 and GB/T 26482

For fire-safe performance, China uses a family of standards rather than a single one:

GB/T 26479 is a modified adoption of API 607 / ISO 10497. The test exposes the closed valve to a flame for 30 minutes at 750-1000 deg C, measures internal and external leakage during the fire and after cooling, and confirms the valve can still be operated. For check valves, GB/T 26482 is the equivalent of API 6FD.

The GB/T 26480 Confusion

A common error in supplier literature is to cite GB/T 26480 as the fire-test standard. It is not. GB/T 26480 is the Chinese pressure-test and inspection standard (the API 598 / ISO 5208 equivalent, paralleled by JB/T 9092). Fire testing is covered by GB/T 26479 (quarter-turn) and GB/T 26482 (check), not by GB/T 26480. If a quote lists GB/T 26480 for fire safety, the supplier has confused pressure testing with fire testing — push back and ask for the actual GB/T 26479 or API 607 certificate.

What to Demand on a Quote

1. For cryogenic duty: name GB/T 24925, state the design temperature, and confirm the extended-bonnet length against your insulation.
2. For the 2019 edition requirements: confirm cryogenic treatment (below -100 deg C) and the fugitive-emission figure if emissions matter to the project.
3. For fire-safe duty: require GB/T 26479 (or API 607 / ISO 10497) for quarter-turn valves and GB/T 26482 (or API 6FD) for checks, with the test house named.
4. Do not accept "GB/T 26480" as a fire-safe certificate — it is a pressure-test standard.
5. Remember that China has no single national fire-test standard replacing API 607 / 6FA; exports are normally tested directly to API 607 / ISO 10497, so the certificate should name that standard explicitly.

The PN vs ASME Class conversion guide explains why a PN16 cryogenic valve and a Class 150 valve are not the same pressure envelope, and the ValveSpecs Pro database records the standards each manufacturer's cryogenic and fire-safe products are built and tested to, so a quoted GB/T 24925 or GB/T 26479 claim can be checked against the listed compliance.