ISO 10631:2013 specifies requirements for design, materials (e.g. steel, cast iron, ductile iron, copper alloy), pressure/temperature ratings, and testing for butterfly valves having metallic bodies for use in general purpose flanged or butt welding piping systems. ISO 10631:2013 covers butterfly valves of the following nominal sizes, DN and NPS: DN 40; 50; 65; 80; 100; 125; 150; 200; 250; 300; 350; 400; 450; 500 (550); 600 (650); 700; 750; 800; 900; 1 000; 1 200; 1 400; 1 600; 1 800; 2 000; 2 200; 2 400; NPS 1 1/2; 2; 2 1/2; 3; 4; 5; 6; 8; 10; 12; 14; 16; 18; 20; (22); 24; (26); 28; 30; 32; 36; 40; 48; 56; 64; 72; 80; 88; 96. ISO 10631:2013 is applicable to butterfly valves of the following pressure designations, PN and class: PN 2,5; 6; 10; 16; 25; 40; class 125; 150; 300.