Overview
ISO 20602:2019 - Ships and marine technology - specifies design, manufacturing and testing requirements for cryogenic check valves intended for very low temperature environments (−50 °C to −196 °C). The standard targets valves used in marine and shipboard systems handling liquefied gases (e.g., LNG, natural gas, liquid nitrogen) and establishes requirements to ensure leakage stability and reliable operation under cryogenic conditions.
Key topics and technical requirements
- Scope and temperature range: Covers check valves for low-temperature service between −50 °C and −196 °C.
- Pressure–temperature rating: Defines working pressure and design-temperature considerations; valve class and maximum working pressure follow ASME B16.34 classing (manufacturers and purchasers can agree when class exceeds 900).
- Materials and components: Requirements for body, cover/bonnet, disc, seat, gaskets, hinges, bolts/nuts and their materials suitable for cryogenic service.
- Design features: Guidance on general check valve structures and selection of disc/seat types for reliable sealing at low temperatures.
- Manufacturing processes: Surface treatment, welding and heat treatment requirements to maintain material integrity in cryogenic conditions.
- Testing and inspection:
- Material tests and non-destructive inspection (NDE) including radiographic testing (RT), penetrant testing (PT), and ultrasonic testing (UT).
- Pressure tests, visual and dimensional inspections, heat treatment verification.
- Cryogenic tests and fire safety tests where applicable; procedures and reporting requirements for test results.
- Marking and documentation: Identification and marking requirements to support traceability and compliance.
- Informative annex: Examples of cryogenic check valve designs.
Practical applications and users
ISO 20602:2019 is applicable to:
- Valve manufacturers designing and certifying cryogenic check valves for marine and offshore use.
- Shipbuilders, naval architects and offshore engineers specifying valves for LNG carriers, FPSOs, gas-fuelled ships and cryogenic piping systems.
- Classification societies, inspection bodies and purchasers requiring standardized acceptance criteria for leakage performance and testing.
- Maintenance and QA teams ensuring in-service valves meet cryogenic performance expectations.
Typical systems: LNG bunkering and transfer lines, cryogenic cargo piping, fuel gas supply systems on ships, and nitrogen systems.
Related standards
Standards referenced include ISO 28921-1, ASME B16.34, API 594, API 598, BS 6364, and relevant ASTM/ASME material and NDE standards. These provide complementary guidance on dimensions, testing methods and material specifications.
Keywords: ISO 20602:2019, cryogenic check valves, low temperature applications, ships and marine technology, design and testing requirements, LNG valves, leakage stability, pressure–temperature rating, non-destructive testing.
Open preview (PDF)Ships and marine technology — Check valves for use in low temperature applications — Design and testing requirements
