Dual plate wafer check valve with cast stainless CF8M half-discs in a coated metallic body, for clamping between pipe flanges. The two spring-loaded plates close as forward flow decays, before the column can reverse.
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Two half-discs are hinged on a central pin and held closed by torsion springs. Forward flow folds them open into the bore; as the flow decays the springs shut them, so the valve closes on falling flow rather than on reverse flow. The face-to-face length is a fraction of a flanged swing check of the same bore, which is why the wafer pattern is used where pipe runs are tight or valve weight matters.
On the unit photographed the plates, hinge pin, stop pin and springs are stainless: both plates are cast CF8M, the ASTM A351 grade equivalent to AISI 316. The body is a painted casting and carries no material mark, so the body metal — cast iron, ductile iron or carbon steel — must be stated on the order rather than assumed from the photograph. Where the body is cast iron, the governing European standard is EN 16767, metallic check valves, which replaced the withdrawn EN 12334 in 2016; for cast iron flanged and wafer bodies it covers PN 2,5 to PN 25 and Class 125 and Class 250.
Order by nominal size, body material, seat material and — because the valve is clamped between two flanges — the flange standard and rating. ASME B16.5 Class 150/300 and EN 1092-1 PN 10/16/25/40 are drilled differently and will not substitute for one another.
| Valve Type | Dual plate (twin half-disc) spring-assisted check valve |
|---|---|
| Plate (Disc) Material | Cast stainless steel, both plates cast 'CF8M' — ASTM A351 grade CF8M, the cast equivalent of AISI 316 |
| Body Material | No legible material mark on the photographed unit — the body is a painted casting and the one cast mark on it is obscured by the paint. Specify cast iron, ductile iron or carbon steel on the order. |
| Body Style | Wafer — centred on the flange bolts and clamped between two flange faces |
| Internals | Stainless steel hinge pin, stop pin and torsion springs |
| Design Standard for the Type | API 594 — Check Valves: Flanged, Lug, Wafer, and Butt-welding — Type A, short face-to-face, wafer body, dual plate |
| Standard if the Body is Cast Iron | EN 16767:2020 — Industrial valves. Metallic check valves — is the current European standard for this type; it replaced EN 12334 (cast iron check valves), which was withdrawn in 2016. For cast iron flanged and wafer bodies EN 16767 covers PN 2,5; PN 6; PN 10; PN 16 and PN 25, and Class 125 and Class 250. Conformity is not marked on this stock. |
| Flange Compatibility | ASME B16.5 (Class 150/300) and EN 1092-1 (PN 10/16/25/40) are drilled differently and are not interchangeable — state the flange standard and rating on the order |
