This document specifies the general requirements for metallic check valves, which are forged, cast or fabricated in straight, angle or oblique pattern (see EN 736 2) with end connections flanged or wafer, butt welding, socket welding, or threaded. This document applies to metallic check valves used for all industrial applications. Additional requirements given in the relevant application standards may apply to check valves used for more specific applications (e.g. for the water industry, the chemical and petrochemical process industry, the gas distribution industry). Sanitary check valves and back flow prevention anti-pollution check valves are excluded from the scope of this document. The range of nominal sizes covered is: DN 8, DN 10; DN 12, DN 15; DN 20; DN 25; DN 32; DN 40; DN 50; DN 65; DN 80; DN 100; DN 125; DN 150; DN 200; DN 250; DN 300; DN 350; DN 400; DN 450; DN 500; DN 600; DN 700; DN 750; DN 800; DN 900; DN 1 000; DN 1 200. DN 8 and DN 12 are not used for PN designated flanged end connections. DN 8, DN 10 and DN 12 are not used for Class designated flanged end connections. DN 750 is used for Class designated check valves only. Socket welding end check valves and threaded end check valves are limited to the range DN 8 to DN 65. The range of pressure designations covered is: a) for flanged end and wafer type end cast iron bodies: PN 2,5; PN 6; PN 10; PN 16; PN 25; Class 125; Class 250; b) for flanged end, wafer type and butt welding end bodies in steel or copper alloy materials: PN 2,5; PN 6; PN 10; PN 16; PN 25; PN 40; PN 63; PN 100; PN 160; PN 250; PN 320; PN 400; Class 150; Class 300; Class 600; Class 900 ; Class 1 500; Class 2 500; c) for socket welding end and threaded end bodies in steel or copper alloy materials: PN 40; PN 63; PN 100; Class 600; Class 800. NOTE Class 800 is a widely used Class designation for socket welding and threaded end check valves. The correspondence between DN and NPS is given for information in Annex B.