API RP 14H pdf download Recommended Practice for Installation, Maintenance and Repair of Surface Safety Valves and Underwater Safety Valves Offshore 1 Scope 1.1One of the means of assuring positive welstrean shutoff is the use of the wellhead surface safety valve (SSV) or underwatersafety valve (USV). It is imperative that the SSV/USV be mechanically reliable. It should therefore be operated,...