A wafer check valve is a type of check valve used in pipelines to prevent the backflow of fluid. It is called a "wafer" check valve because of its wafer-like, thin de​sign, which allows it to fit between two pipeline flanges, typically without the need for additional gaskets or bolts. Here are the key features and functions of a wafer check valve:

These threaded, raised-face fittings feature carbon steel construction and are suitable for chemical refineries, fertilizer and petrochemical plants, and natural gas, oil and water transmission systems. They are also suitable for liquefied natural gas plants, nuclear power plants and thermal power plants.