Draft page. The factory document pack for this page is still under review. Values marked “To be confirmed” have not been verified yet.
Cryogenic ball valves
Low-temperature service · BS 6364
A cryogenic ball valve is built for fluids such as LNG, liquid nitrogen and liquid oxygen. It uses an extended bonnet that keeps the stem packing warm, low-temperature body materials, and a way to relieve pressure from liquid trapped in the ball cavity. BS 6364 sets design requirements and a cryogenic type test.
Who makes this valve
We publish one number per API specification, never a factory-by-factory row: a row with its licence set and expiry year would point at a single registry entry. One RFQ is quoted by several panel factories, and each quotation names the manufacturer, its API licence number and where to verify it, so you can check the source before you order. How we check licences
How it compares
| Feature | Standard ball valve | Cryogenic ball valve |
|---|---|---|
| Bonnet | Standard height | Extended bonnet: a gas column keeps the packing well above fluid temperature |
| Cavity pressure | Often bidirectional seats | Cavity relief: vented ball or self-relieving seat, which can make the valve unidirectional |
| Body materials | Carbon or stainless steel | Austenitic stainless steel such as CF8M or F316 for very low temperature |
| Type test | Ambient shell and seat test | Additional low-temperature test, for example BS 6364 or ISO 28921-1 |
Specification range
Grades listed are common ASTM designations for cryogenic service. The range offered by the partner factory and any type-test report are confirmed before this page goes live.
| ASTM grade | Form | Sizes (NPS) | Pressure classes | End connections | Partner factory supplies |
|---|---|---|---|---|---|
| ASTM A351 CF8M | Cast 316 stainless steel | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A182 F316 | Forged 316 stainless steel | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A351 CF8 | Cast 304 stainless steel | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A182 F304 | Forged 304 stainless steel | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
Pressure–temperature rating
The shell rating follows ASME B16.34 for the body material group; austenitic and duplex stainless steels are in different groups with their own values, so confirm the rating for the exact grade. For reference, the table shows group 1.1 Standard Class values at −29 °C to 38 °C. The minimum design temperature and the rating of the partner factory valve are to be confirmed.
| Pressure class | Max. working pressure (bar) | (psi) |
|---|---|---|
| Class 150 | 19.6 | 285 |
| Class 300 | 51.1 | 740 |
| Class 600 | 102.1 | 1,480 |
| Class 900 | 153.2 | 2,220 |
| Class 1500 | 255.3 | 3,705 |
| Class 2500 | 425.5 | 6,170 |
Partner factory P-T curve for this valve: To be confirmed
Why cryogenic valves have long stems
The extended bonnet places the stem packing far from the cold fluid. Vapour forms in the bonnet and insulates it, so the packing stays warm enough to seal and the operator does not freeze. Valves with an extended bonnet are normally installed with the stem within a set angle of vertical.
BS 6364 and ISO 28921-1 set design requirements for low-temperature valves, so the bonnet length and the installation angle should be stated in the purchase order.
Cavity vent and cavity relief
Liquid trapped in the ball cavity of a closed valve can warm up and expand into gas, raising pressure well above line pressure. A vent hole on the upstream side of the ball, or seats that relieve automatically, prevent this. A vented ball makes the valve unidirectional, so the flow arrow must be respected.
Materials at low temperature
Low-temperature service is limited by toughness, not only by strength. Austenitic stainless steel grades such as CF8M and F316 keep their toughness at LNG temperature; ASTM A351 covers the cast grades and ASTM A182 the forged grades.
Carbon steel can be used at moderately low temperature when it is impact tested, for example ASTM A350 LF2 forgings. ASME B16.34 lists the minimum temperature and impact-test requirements for each material group, so the design temperature in the datasheet decides which group is acceptable.
BS 6364 and ISO 28921-1
BS 6364 covers design requirements for cryogenic valves and a low-temperature type test, typically at about −196 °C with a gas such as helium as the test medium. ISO 28921-1 covers design, manufacturing and production testing for low-temperature isolating valves and is the ISO route to the same evidence.
A type test applies to a design, so ask which size, class and seat design the report covers, and whether the test was witnessed. No partner factory report has been received; no low-temperature test result is claimed on this page until a report has been reviewed.
Tests and documents to request
API 6D and API 598 shell and seat tests are carried out at ambient temperature; on their own they do not prove low-temperature performance. That evidence comes from the separate type test to BS 6364 or ISO 28921-1.
Ask for the pressure-test record for each serial number, EN 10204 3.1 material certificates with the impact-test results, and the low-temperature type-test report. Check that the report covers the size, class and seat design you are buying.
Datasheet and drawings
Datasheet: To be confirmed
A datasheet, dimension drawing and STEP file will be published here, without factory branding, after the panel factory authorises them. Until then, ask for them in your RFQ.
Prices, lead times and minimum order quantities are quoted per enquiry against the datasheet you send; they are not listed on this page.
Frequently asked questions
- What is a cryogenic ball valve?
- It is a ball valve designed for liquefied gases far below 0 °C. Key features are an extended bonnet, low-temperature materials, cavity relief and a low-temperature type test.
- Why do cryogenic valves have long stems?
- The long stem and extended bonnet keep the packing away from the cold fluid. A gas column forms in the bonnet and insulates the packing, so it keeps sealing and the handwheel or actuator does not ice up.
- What is the purpose of a vented ball valve?
- A vent hole in the ball releases pressure from the body cavity to the upstream side. In cryogenic service this stops trapped liquid from building up pressure as it warms. It makes the valve unidirectional.
- What is the ASME B16.34 standard?
- ASME B16.34 covers steel and alloy valves with flanged, threaded and welding ends. It sets pressure–temperature ratings by material group and pressure class, minimum wall thickness and testing.
- What is the difference between BS 6364 and ISO 28921-1?
- BS 6364 is the British standard for cryogenic valves: design requirements plus a low-temperature type test. ISO 28921-1 is the ISO standard for low-temperature isolating valves, covering design, manufacturing and production testing. A project may name either; check the edition, the test temperature and the size and class the report covers.
- Who are the manufacturers of cryogenic ball valves?
- Global valve groups and many Chinese factories make them. The useful check is evidence, not origin: a type-test report that covers the size and class you need, and an API licence you can look up in the API Composite List.
Standards cited
- BS 6364: Valves for cryogenic service: design requirements and a low-temperature type test. Edition quoted to: BS 6364:1984 (withdrawn by BSI in 2021 but still named in many LNG specifications).
- ISO 28921-1: Isolating valves for low-temperature applications: design, manufacturing and production testing. Edition quoted to: ISO 28921-1:2022 (BS EN ISO 28921-1:2022).
- ASTM A351: Austenitic stainless steel castings for pressure-containing parts; grades CF8 and CF8M are common for valve bodies.
- ASTM A182: Forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service.
- ASTM A350: Carbon and low-alloy steel forgings that require notch toughness testing for low-temperature service.
- ASME B16.34: Valves with flanged, threaded and welding ends: pressure–temperature ratings by material group and pressure class. Edition quoted to: ASME B16.34-2025.
- API Spec 6D: Pipeline and piping valves: design, manufacture, testing and documentation of ball, gate, plug and check valves.
- API Std 598: Valve inspection and pressure testing (shell, backseat and seat).
- EN 10204: Types of inspection documents, including the 3.1 and 3.2 certificates.