API Standards for Typical Valve Requirements
API - American Petroleum Institute www.api.org
API 600 - Steel Valves - Flanged & Buttwelding Ends
API 600 is the primary steel gate valve purchase specification. API 600 details valve design/construction criteria as well as material/trim designations. ISO 10434 is a similar spec published in the ISO format.
API 602 - Compact Steel Gate Valves-Flanged, Threaded, Welding and Extended-Body Ends
API 602 is for 4" and smaller forged steel gate valves. Like API 600 the spec details valve design/construction criteria as well as material/trim designations.
API 603 - Class 150, Cast, Corrosion-Resistant, Flanged-End Gate Valves
API 603 is the purchase specification for light-walled threaded gate valves ranging through ½" to 24" in ANSI 150, 300 and 600. API 603 is for thin walled applications where the thicker API 600 is not required.
API 607 (API 6FA) -API 607 is a fire test for soft-seated quarter turn valves; the standard covers testing and performance requirements for valves exposed to certain fire conditions defined in the standard. The procedures defined in this standard apply to all valves made from materials listed in ASMB B16.34. API 6FA is the fire test spec for API Spec 6A and 6D valves; API 6FC is the fire test for valves with automatic backseatsAPI Spec 6A and 6D valves.
API 608 - Metal Ball Valves- Flanged and Butt-Welding Ends
API 608 is the purchase specification for class 150 and 300 metal ball valves. Design and construction criteria are detailed in this spec.
API 609 - Butterfly Valves, Lug-Type and Wafer Type
API 609 is the purchase specification for lug and wafer type butterfly valves for installation between ANSE B16 flanges up to Class 600
API 598 Valve Inspection & Testing
API 598 details all the testing and inspection requirements for gate, globe, plug, ball, check and butterfly valves. ASME/ANSI B16.34 determine the test pressures required for API 598.
API 6D Specification for Pipeline Valves (Plug, Gate, Ball and Check Valves)
API 6D is the standard used for valves in pipeline service. API 6D has more stringent testing requirements compared to the API 600, 602, 608 or 609 design criteria. API 6D check valves are used in applications requiring pigging as the spec indicates the flapped cannot impede flow through the valve.
API specifications can be purchased at http://global.ihs.com/?RID=API1 by searching for the specific specification.
Contact - The Valve Pipeline
Forged valves usually cost more but you don't need to worry about bad castings i.e. porous castings.