What is the significance of API 608 compliance for valves?
The API 608 valve standard “Metal Ball Valves - Flanged, Threaded and Welding Ends” is a valve standard which is actually an additional set of requirements beyond those mentioned in the ASME B16.34 standard, and compliance to the latter is a prerequisite.
This standard has been developed by the API in 1989 as the standard to be used by “downstream” refineries and chemical plants for the selection and approval of ball valves.
Some of these additional requirements for a ball valve to comply with API 608 are :
- There must be an electrical continuity between stem-ball-body (anti-static device).
- Hollow balls are not allowed (unless specifically accepted by the customer).
- Maximum operating load on handles or handwheels is limited to 80lbs.
- Stem torsional strength must be at least 2x the maximum operating torque.
- If the stem is to fail, it must fail outside of the pressure-containing part of the valve and above the stem packing.
- PTFE & RPTFE seats and sealing elements must meet certain minimum pressure/temperature requirements.
- The ball valves (full, regular and reduced bore) must meet minimum bore diameter requirements.