Understanding how SP-55 relates to other standards helps you use it correctly.
MSS SP-55, titled Quality Standard for Steel Castings for Valves, Flanges, Fittings, and Other Piping Components – Visual Method for Evaluation of Surface Irregularities , provides a universally accepted benchmark for determining the acceptability of these surface conditions. It serves as a primary reference document for manufacturers, inspectors, and end-users to define what constitutes a "quality" surface versus a defect requiring repair. mss sp55 standard pdf work