Wafer check valves, also known as dual-plate check valves, have two spring loaded half-moon shaped discs that rotate about their shaft. The disc plates are kept shut by a torsion spring. When fluid flows in a forward direction, the pressure of the fluid causes the disc plates to swing open, allowing flow. The check valve is closed by the spring as soon as flow ceases, before any reverse flow can occur.

Normative reference

API 6D Pipeline Valves

API 594 Check Valves: Flanged, Lug, Wafer and Butt-Welding

ASME B16.34 Valves Flanged, Threaded and Welding Ends

ASME B16.5 Pipe Flanges and Flanged Fittings: NPS 1/2 through 24

ASME B16.47 Series A Large Diameter Steel Flanges: NPS 26 Through NPS 60 Metric/Inch Standard

ASME B16.25 Buttwelding Ends

ASME B16.10 Face to Face and End to End Dimensions of Valves

MSS SP-25 Standard Marking System for Valves, Fittings, Flanges and Unions

Size available

NPS 2 to NPS 24 (DN50 to DN600)

Pressure rating available

Class 150 to Class 900