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

Class 150

Standard Material Specification Part Name Material Body A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M Disc A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M Pin A182 F6a, A182 F22, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L Spring AISI 9260, AISI 6150, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L Dimensions and Weights Size mm 50 65 80 100 125 150 200 250 300 350 400 450 500 600 in 2 2 ½ 3 4 5 6 8 10 12 14 16 18 20 24 L (mm) 60 67 73 73 86 98 127 146 181 184 191 203 219 222 H (mm) 103 122 135 173 196 222 279 339 409 450 514 549 606 717 Weight (kg) 2 3.2 4 6 9 12 22 38 54 80 118 210 240 410

Class 300

Standard Material Specification Part Name Material Body A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M Disc A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M Pin A182 F6a, A182 F22, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L Spring AISI 9260, AISI 6150, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L Dimensions and Weights Size mm 50 65 80 100 125 150 200 250 300 350 400 in 2 2 ½ 3 4 5 6 8 10 12 14 16 L (mm) 60 67 73 73 86 98 127 146 181 222 232 H (mm) 110 129 148 180 215 250 307 361 422 485 539 Weight (kg) 3.5 5 7 10 18.5 19 33 54 88 128 169

Part Name	Material
Body	A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M
Disc	A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M
Pin	A182 F6a, A182 F22, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L
Spring	AISI 9260, AISI 6150, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L

Size	mm	50	65	80	100	125	150	200	250	300	350	400
	in	2	2 ½	3	4	5	6	8	10	12	14	16
L (mm)		60	67	73	79	105	136	165	213	229	273	305
H (mm)		110	129	148	192	240	265	319	399	456	489	562
Weight (kg)		3.5	5	7	12	22.5	35	45	77	110	135	163

Part Name	Material
Body	A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M
Disc	A216 WCB, A352 LCB, A351 CF8, A351 CF8M, A351 CF8C, A351 CF3, A351 CF3M
Pin	A182 F6a, A182 F22, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L
Spring	AISI 9260, AISI 6150, A182 F304, A182 F316, A182 F321, A182 F304L, A182 F316L

Size	mm	50	65	80	100	150	200
	in	2	2 ½	3	4	6	8
L (mm)		70	83	83	102	159	206
H (mm)		142	164	167	205	288	358
Weight (kg)		6.5	9	14	24	43	56