Wafer Check vs Lug Check Valve

Wafer and lug are two body styles for dual plate (double-disc) check valves per API 594. Both fit between pipe flanges, but they differ in how they mount and whether they support dead-end service or one-sided disassembly.

Comparison Table

Feature	Wafer Check Valve	Lug Check Valve
Body design	Thin disc, no bolt holes	Body with threaded lug holes
Mounting method	Sandwiched between flanges by through-bolts	Bolted to each flange independently
Dead-end service	Not suitable	Suitable (one flange can be removed)
One-sided disassembly	Not possible	Possible (remove downstream flange)
Weight	Lighter	Slightly heavier (lugs add material)
Cost	Lower	~10-15% more than wafer
Standard	API 594, Type I	API 594, Type II
Pressure rating	ASME B16.34 Class 150-2500	ASME B16.34 Class 150-2500
Size range	2” to 48”	2” to 48”
Flange compatibility	ASME B16.5, B16.47	ASME B16.5, B16.47
Piping support	Flanges support valve	Valve self-supporting on one side

Key Differences

Mounting mechanism. A wafer check valve has no holes in the body. It is held in place solely by the compression of two flanges bolted together with long through-bolts. A lug check valve has threaded holes (lugs) around its circumference. Each pipe flange is bolted to the valve body with separate, shorter bolts.

Dead-end service. This is the primary functional difference. In dead-end service, one side of the valve has no piping connected (e.g., at the end of a header before future expansion). A wafer valve cannot be used because there is no downstream flange to clamp against. A lug valve can serve as a dead-end because it bolts independently to the upstream flange.

One-sided disassembly. Lug check valves allow removal of downstream piping without disturbing the valve or upstream connection. This is valuable for maintenance access. Wafer valves require both flanges to remain bolted to keep the valve in place.

Internal design. Both wafer and lug check valves use the same dual plate (double-disc) internal mechanism with torsion springs on a central hinge pin. The difference is exclusively in the body exterior and mounting arrangement.

Pro Tip

Default to lug-type check valves at header terminations, tie-in points for future expansion, and any location where one-sided disassembly may be needed during maintenance. The small cost premium over wafer style is easily justified by the installation flexibility.

For a detailed comparison of swing check vs dual plate designs, see the guide to check valve types.

Read the full guide to valve types