Category
Valves
Subcategory
Quarter-Turn
Applicable standards
4
Issuing bodies
3
Description
Wafer / lugged butterfly valve — concentric, double-offset or triple-offset.
Applicable Standards (4)
API — 2 standards
API 609
Butterfly Valves: Double-Flanged, Lug- and Wafer-Type
Butterfly valves Class 150 through 600, lug, wafer and double-flanged designs.
Key requirements (6)
- Butterfly valves — Category A (concentric soft-seated, ANSI Class 125/150) and Category B (high-performance double or triple offset).
- Cat A: utility / general service; rubber-lined or PTFE-lined.
- Cat B (double-offset): metal- or soft-seated; bidirectional zero-leakage.
- Cat B triple-offset: torque-seated, fire-safe, high-temp.
- Hydrotest per API 598.
- Wafer or lugged body styles.
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 17292
Metal ball valves for petroleum, petrochemical and allied industries
Floating and trunnion-mounted metal ball valves; international counterpart to API 608.