For isolating valves in low-temperature and cryogenic service, the current international standards are ISO 28921-1 (design, manufacturing and production testing) and ISO 28921-2 (type testing). Both cover design temperatures from −50 °C down to −196 °C. BS 6364, the British specification for cryogenic valves published in 1984, is listed by BSI as withdrawn since July 2021.
This page sets out what each document covers and what to write into a purchase specification. It does not tell you which standard a particular valve meets: ask the supplier for the test records.
ISO 28921-1:2022
Full title: Industrial valves – Isolating valves for low-temperature applications – Part 1: Design, manufacturing and production testing. According to the listing of the adopted European edition (EVS-EN ISO 28921-1:2022), it:
- Covers gate, globe, ball or plug, and butterfly valves used as isolation and check valves
- Covers design temperatures from −50 °C down to −196 °C
- Applies to valves whose body, bonnet, extension or cover is metallic
- Covers nominal sizes DN 10 to DN 1800 (NPS ⅜ to 72), PN 16 to PN 400 and Class 150 to Class 2500, though not every size and type in every rating
- Does not apply to safety valves or control valves
- Does not apply to valves for cryogenic service designed to ISO 21011 for use with cryogenic vessels
- Takes precedence where it differs from the valve product standards
ISO 28921-2:2015
Full title: Industrial valves – Isolating valves for low-temperature applications – Part 2: Type testing. According to the Swedish Institute for Standards listing, where it is shown as in force, it:
- Sets requirements for type testing isolating valves to verify their performance at low temperature, from −50 °C down to −196 °C
- Does not evaluate actuators unless they are an integral part of the valve; valves may be operated by hand or by an actuator during the test
- Does not apply to valves designed to ISO 21011 for use with cryogenic vessels
BS 6364:1984
BS 6364, Specification for valves for cryogenic service, was published by BSI in 1984. BSI Knowledge lists it as withdrawn on 23 July 2021 and names no replacement.
Some purchaser specifications still refer to it. If yours does, decide whether to keep the reference, move to ISO 28921, or name both, and say which tests and acceptance criteria apply. A reference to a withdrawn standard with no edition or test details leaves the supplier to guess.
Production tests and type tests
Production testing (Part 1) is done on the valves being made for your order. A type test (Part 2) checks a valve design at low temperature, so that the design is proven before it is supplied.
Ask whether the offer includes a type test record for the design, production tests on each valve, or both, and whether the records will be supplied with the valves.
What to write into the specification
- The standard and its edition for design and production testing, for example ISO 28921-1:2022
- Whether a type test to ISO 28921-2 is required for this order, or an existing type test record for the same design is acceptable
- Any project requirements for test temperature, test medium and acceptable leakage, in addition to the standard
- Which valves are tested: every valve, a sample, or the design only
- Hold and witness points, and who attends
- The test records to be supplied with the valves
Valves outside ISO 28921
Safety valves, control valves and valves for cryogenic vessels designed to ISO 21011 are outside the scope of ISO 28921-1. Your project specification has to name the standard and the tests that apply to them separately. For a control valve or a regulator, see control valve or pressure regulating valve.
Questions
- Is BS 6364 still current?
- No. BSI lists BS 6364:1984 as withdrawn since 23 July 2021, with no replacement named.
- Does ISO 28921-1 cover control valves?
- No. It does not apply to safety valves or control valves. Name the standard for those separately in your specification.
- What temperatures do ISO 28921-1 and ISO 28921-2 cover?
- Design temperatures from −50 °C down to −196 °C.
Sources
Published by EVOSNT Trading FZCO (EVO LNG Supply). General guidance for engineers and buyers; the purchaser's specification and the applicable standards govern the design and testing of any valve. See our valve range.
