MSS SP-25 Marking System for Valves, Fittings, Flanges and Unions

1.1 This Marking system applies to valves, fittings, flanges and unions used in piping connections which include (but nare not limited to) flanged, soldered, brazed, threaded or welded joints.

1.2 These specified markings serve to identify the manufacturer, the rating designation,materials of construction and special service limitations imposed by the manufacturer.The are used for product identification and to assist in proper application.