API RP 591 - 2014 5th Edition - Process Valve Qualification Procedure

This recommended practice (RP) provides recommendations for evaluation of a manufacturer's valve construction and quality management system for the purpose of determining a manufacturer's capability to provide new valves manufactured in accordance with the applicable standards listed in Section 2.Qualification of valves under this RP is "manufacturing facility specific" and does not cover valves manufactured by other manufacturing facilities, whether owned by the same manufacturer or a third party.