MSS Standard
MSS SP-91: Guidelines for Manual Operation of Valves
MSS SP-91 Standard Practice provides guidelines for the operation of manually actuated valves as affected by the valve operator’s input....
MSS SP-55: Quality Standard for Steel Castings for Valves
The MSS SP-55, Quality Standard for Steel Castings for Valves, Flanges, Fittings, and Other Piping Components– Visual Method for Evaluation of Surface Irregularities...