Category
Valves
Subcategory
Specialty Valve
Applicable standards
4
Issuing bodies
4
Description
Extended-bonnet cryogenic valve qualified for LNG, ethylene, LIN/LOX/LAR, etc.
Applicable Standards (4)
API — 1 standard
API 598
Valve Inspection and Testing
Inspection, examination, supplementary examinations and pressure-test requirements for valves.
Key requirements (5)
- Valve inspection and testing — covers the test requirements referenced by other valve standards.
- Tests: shell (high-pressure water), backseat (where applicable), low-pressure pneumatic seat, high-pressure hydrostatic seat, optional high-pressure pneumatic seat.
- Allowable leakage: zero for resilient-seated; small allowable rate for metal-seated (Table 6).
- Test duration: minimum hold times by valve size.
- Visual examination during pressurization.
ASME — 1 standard
ASME B16.34
Valves — Flanged, Threaded, and Welding End
Pressure-temperature ratings, dimensions, materials, NDE, marking and testing for valves.
Key requirements (7)
- Pressure–temperature ratings for valves (steel).
- Pressure classes: 150, 300, 400, 600, 900, 1500, 2500, 4500.
- Body wall thickness: t = (P·d)/(2·S·E − 1.2·P) + c, plus tabulated minimums.
- Hydrotest: shell at 1.5 × Class 100 °F rating; seat at 1.1 × Class 100 °F rating.
- Special class allows 25% above standard rating with stricter NDE (radiography + hardness).
- Materials per ASME II Part D allowable stress.
- End connections: threaded, flanged, butt-weld, socket-weld.
ISO — 1 standard
ISO 21011
Cryogenic vessels — Valves for cryogenic service
Cryogenic valve qualification (ISO).
BSI — 1 standard
BS 6364
Specification for valves for cryogenic service
Cryogenic valves — extended bonnet, low-temperature testing.
Key requirements (5)
- Valves for cryogenic service — gate, globe, ball, butterfly, check.
- Extended bonnet design — gas column above stuffing box prevents stem packing freezing.
- Cryogenic test: cool to LIN (−196 °C), cycle, measure leakage.
- Allowable seat leakage at cryo: small allowance (typically a few cc/min for gas).
- Materials: austenitic SS, bronze, Monel; charpy tested at min temp.