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- API 594 — Check Valves — Wafer, Wafer-Lug and Double Flanged Types
- API 594 — Check Valves — Wafer, Wafer-Lug and Double Flanged Types
API 594 — Check Valves — Wafer, Wafer-Lug and Double Flanged Types
The dimensional and construction standard for compact check valves. If your enquiry says "dual plate check valve to API 594", this is the page that tells you what that actually fixes.
API 594 covers swing check and dual plate check valves in wafer, wafer-lug and double flanged execution, in Class 150 to 2500. Its main contribution is a face-to-face and wafer-dimension table that lets a dual plate check replace a flanged swing check in a line without re-piping.
The standard also defines the spring-loaded plate geometry, the seat and stop arrangements, and the testing that demonstrates crack-open behaviour and reverse leakage. Because a dual plate check closes before reverse flow fully develops, its slam behaviour and its pressure drop are both different from a swing check — and both are worth checking against the actual line.
We supply API 594 dual plate check valves in ductile iron, WCB, CF8M, WC6, duplex and super duplex, with RTFE, PTFE, EPDM or metal seats, and swing check valves in double flanged execution.
Coverage
- Swing and dual plate check valves
- Wafer, wafer-lug and double flanged ends
- Class 150 – 2500
- NPS ½ – NPS 60 typical
- Retainerless options for fugitive-emission service
- Seat and shell testing to API 594 / API 598
Related standards
Send the piping class, not the part number
We check the dimensions, the material and the standard before we price — which is the part that decides whether the valve actually fits. RFQ answered within one working day.