API RP 591 PDF

Provides recommendations for evaluation of a manufacturer's valve construction and quality assurance program for the purpose of determining a manufacterer's capability to provide new valves manufactured in accordance with the applicable API standards. Qualification of valves under this recommended practice is "manufacturing facility specific" and does not cover valves manufactured by other manufacturing facilities, whether owned by the same manufacturer or a third party. Ffugitive emissions testing is outside the scope of this RP.