Cryogenic Globe Valve
Valves / Globe ValveA cryogenic globe valve is a globe valve designed for extremely low-temperature service (below -46°C to -196°C), handling liquefied gases such as LNG, liquid nitrogen, and liquid oxygen with an extended bonnet that protects packing and operating components from cryogenic exposure.
Working Principle
The operating principle mirrors a standard globe valve — a disc lifts off or lowers onto a seat to control flow. The critical difference is the extended bonnet, which creates a vapor column that allows the cryogenic fluid to warm gradually as it rises up the stem. By the time the stem reaches the packing gland, the temperature has risen above the frost point, keeping the packing pliable and the handwheel operable. The body and internal components use austenitic stainless steel (304, 316, 316L) that retains ductility at cryogenic temperatures. Seat materials use PCTFE (Kel-F) or PTFE compounds that maintain sealing elasticity at -196°C.
Key Components
Austenitic stainless steel body, extended bonnet with vapor column, disc (stainless or PCTFE-faced), seat ring, stem, PTFE/PCTFE packing, handwheel or actuator.
Types & Variants
| Type | Key Feature | Typical Use |
|---|---|---|
| Cryogenic throttling globe | Extended bonnet + contoured disc | LNG plant flow regulation |
| Cryogenic isolation globe | Extended bonnet + flat disc | LOX/LN2 storage isolation |
| Cryogenic forged globe | Small-bore forged body, Class 800+ | Instrument connections in cryo service |
| Cryogenic Y-pattern globe | 45° bonnet + extended | Low pressure drop cryo throttling |
Common Materials
ASTM A351 CF8 (304 SS) or CF8M (316 SS) castings. ASTM A182 F304/F316/F316L forgings. Extended bonnet in same material. Seat inserts: PCTFE for temperatures below -150°C, PTFE for temperatures above -150°C. Stem packing: PCTFE or graphite (if bonnet extension is sufficient to keep packing above -29°C).
Applicable Standards
- BS 6364 (cryogenic valves)
- API 602 (forged globe valves, reference)
- ASME B16.34 (pressure ratings)
- MSS SP-134 (cryogenic valve requirements)
- EN 1626 (cryogenic valves for LNG)
Industrial Applications
- LNG liquefaction and regasification terminals
- Liquid nitrogen/oxygen/argon distribution
- Air separation cryogenic columns
- Cryogenic ethylene processing
- Space program propellant handling
Advantages & Disadvantages
Advantages
- Excellent throttling capability at cryogenic temperatures
- Extended bonnet protects packing from freeze-up
- Metal-to-metal seating available for fire-safe requirement
- Austenitic stainless steel retains toughness at -196°C
Disadvantages
- Extended bonnet increases overall valve height significantly
- Higher cost than standard globe valves
- Cryogenic testing (helium leak at temperature) is expensive
- PCTFE seats have limited pressure/temperature capability compared to metal seats
Selection Guide
- Specify the exact minimum service temperature to determine bonnet extension length and seat material
- For temperatures below -150°C, PCTFE seats outperform PTFE (PTFE cold-flows excessively at these temperatures)
- Demand cold leak testing per BS 6364 at the rated temperature, not just ambient
- Ensure the bonnet extension is long enough to keep packing above -29°C — calculate based on the actual fluid temperature, not just the class rating
Practical Tips
- A cryogenic globe valve that passes ambient testing can still leak at -196°C — differential thermal contraction between the disc and seat can open a gap that did not exist at room temperature
- In LNG service, the valve must be cooled down slowly (typically 1-2°C per minute) to avoid thermal shock cracking the seat inserts
FAQ
What testing is required for a cryogenic globe valve?
BS 6364 requires helium leak testing at the rated cryogenic temperature. The valve is cooled in a liquid nitrogen bath and tested with helium at 0.1 MPa to verify seat and shell leakage rates below the specified limits.
Can a cryogenic globe valve be used for throttling?
Yes. Globe valves inherently provide excellent throttling capability, and this advantage carries over to cryogenic service. Contoured (parabolic) discs provide the best flow characteristic for regulation duty.