API 600 Steel Valves - Flanged & Buttwelding Ends API 600 is the main steel gate valve specifi cation. Valve design and construction criteria are specifi ed, as well as materials and trim designations. An appendix covers information pertaining to pressure seal valves. ISO Standard 10434 is essentially the same as API 600, re-produced in the ISO format. API 602 Compact Steel Gate Valves - Flanged, Threaded, Welding and Extended-Body Ends API 602 is for 100 NB (4”) & smaller forged steel gates valve specifi cation. Valve design and construction criteria are specifi ed, as well as materials and trim designations. This standard includes requirements for bellows seal gate valves. In 150, 300 and 600 class API 602 requires a heavier wall than ANSI B16.34 API 603 Cast, Corrosion - Resistant, Flanged-End Gate Valves API 603 covers light walled gate valves in sizes NPS 15mm to 600mm (1/2” through 24”), in classes 150, 300 & 600. These valves are used in applications where a thicker API 600 casting is not needed. However, the wall thickness normally conforms to ANSI B16.34 wall. API 608 Steel Ball Valves - Flanged and Buttwelding Ends Typically used for fl oating ball valves, API 608 is the purchase specifi cation for class 150, 300, 600 and 800 class steel ball valves. Valves design and construction criteria are detailed. Trunnion mounted pipeline ball valves are manufactured to API 6D but API 608 is also allowable up to 500 NB (20”). API 609 Butterfl y Valves - Lug-Type and Wafer-Type API 609 is a specifi cation for butterfl y valves with lug-type and wafer-type confi gurations designed for installation between ANSI B16 fl anges, 150 to 1500 class.