The wafer swing check valves have compact dimensions and reduced weight. The wafer swing check valves are easy to be installed, because the valve opens in case of any minimum pressure increase, and closes at any minimum pressure decrease. With the seat inside the body of the valve, and the gasket integrated, the wafer swing check valves can be installed between flanges EN PN 10-16 and ANSI 150, without any need of additional flange gaskets.