What material should a safety & relief valve for LNG / Cryogenic Natural Gas be?

SS 304L (Excellent): Toughness improves at cryogenic temperature - standard LNG valve material. 9% Nickel steel (Excellent): Standard for LNG storage tanks and large valves at -162°C. PTFE (Excellent): Seals and seats maintain flexibility at cryogenic temperatures. Aluminium alloy (Excellent): Used in some LNG service - excellent toughness at -196°C. ASTM A352 LCB (low-temp carbon steel) (Good): Impact-tested to -46°C. Not suitable for liquid LNG at -162°C. ASTM A350 LF2 Class 1 (Good): Forged, impact-tested. Used for cryogenic fittings to -45°C.

LNG / Cryogenic Natural Gas service

Service Selection

Safety & Relief Valves for LNG / Cryogenic Natural Gas Service

Which safety & relief valves configuration suits LNG / Cryogenic Natural Gas, in which material, to which standard — from real service data, with the pitfalls flagged.

Which safety & relief valves for LNG / Cryogenic Natural Gas?

Safety relief valve (ASME Section VIII) - Critical - all LNG vessels require SRV to prevent overpressure Typical service window: 0.1–100 bar (atmospheric storage to HP pumped systems), -162°C to ambient.

Recommended Configurations

Safety relief valve (ASME Section VIII)

Critical - all LNG vessels require SRV to prevent overpressure

Body Material for LNG / Cryogenic Natural Gas

Rated from real compatibility data - click any material for the full decision page.

SS 304LToughness improves at cryogenic temperature - standard LNG valve material.Excellent 9% Nickel steelStandard for LNG storage tanks and large valves at -162°C.Excellent PTFESeals and seats maintain flexibility at cryogenic temperatures.Excellent Aluminium alloyUsed in some LNG service - excellent toughness at -196°C.Excellent ASTM A352 LCB (low-temp carbon steel)Impact-tested to -46°C. Not suitable for liquid LNG at -162°C.Good ASTM A350 LF2 Class 1Forged, impact-tested. Used for cryogenic fittings to -45°C.Good Carbon SteelBrittle fracture risk below -29°C. Never use for cryogenic service.Not Recommended

Governing Standards for LNG / Cryogenic Natural Gas Service

BS 6364 - Cryogenic valve specificationISO 21011 - Cryogenic ball valvesEN 1626 - Cryogenic valvesASME B31.3 Low Temperature Annex MNFPA 59A - LNG facilities

What to Avoid in LNG / Cryogenic Natural Gas Service

Any non-impact-tested carbon steel valve
Valves without extended bonnet in submerged or contact cryogenic service
Elastomer-seated valves (most elastomers embrittle at -162°C)

Service Considerations

Extended bonnet: minimum 150mm to protect stem packing from cryogenic temperature
Thermal cycling test required per BS 6364
Vacuum-insulated pipework may be used for long runs
Blowdown of liquid trapped in valve body - thermal expansion relief essential
All materials must have full material traceability (3.1 certs minimum)