Overview
EN ISO 28921-2:2017 (ISO 28921-2:2015) specifies type testing requirements for isolating valves for low‑temperature applications to verify valve performance from −50 °C down to −196 °C. It defines selection, test conditions and procedural requirements used to demonstrate that a representative valve design family meets low‑temperature operational, leakage and mechanical performance expectations. The standard complements EN/ISO 28921‑1, which covers design, manufacture and production testing.
Key topics and technical requirements
- Scope of testing: Type testing of isolating valves at temperatures between −50 °C and −196 °C; excludes valves designed for cryogenic vessels according to ISO 21011.
- Valve selection: A randomly selected production valve from the design family; mid‑range sizes (DN/NPS) are used to qualify the family and lower pressure classes.
- Operational cycles: 200 cycles for on‑off valves; 3 cycles for check valves.
- Actuator considerations: Actuators are not evaluated unless integral to the valve. Tests may be manual or actuated; effects of cold gas vapours on mounted actuators must be considered.
- Test elements: Cooling procedures, test gas selection, safety provisions, test equipment, and instrument calibration are addressed to ensure repeatable and safe low‑temperature testing.
- Sealing and materials: Selection and qualification of sealing elements and pressure‑retaining components are included; performance at low temperature is assessed.
- Documentation: Information to be supplied by the purchaser, and standardized test records and procedures are provided in annexes (Annex A - test procedure; Annex B - purchaser information; Annex C - test record).
Applications and users
EN ISO 28921‑2 is intended for:
- Valve manufacturers validating low‑temperature valve designs.
- Third‑party test laboratories performing type tests and issuing test evidence.
- Specifiers, purchasers and quality managers writing procurement and acceptance criteria for low‑temperature service.
- Design and inspection engineers involved in piping systems for low‑temperature process plants (industrial gases, LNG handling and similar low‑temperature services - excluding cryogenic vessels designed per ISO 21011).
Practical benefits include verified leak tightness, mechanical reliability and documented performance of valves intended for cold‑service applications.
Related standards
- EN/ISO 28921‑1 - Design, manufacture and production testing for low‑temperature isolating valves
- ISO 21011 - Valves for cryogenic vessels (exclusion noted)
- ISO 5208 - Pressure testing of metallic valves (referenced)
- ASME B31.3 and EN 13480‑2 - Relevant piping/materials guidance
Keywords: EN ISO 28921-2:2017, isolating valves, low-temperature applications, type testing, valve testing, ISO 28921-2, cryogenic exclusion, valve manufacturers.
