The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry announces that technical standards SP-71-2018, Gray Iron Swing Check Valves, Flanged and Threaded Ends and SP-125-2018, Check Valves: Gray Iron and Ductile Iron, In-Line, Spring-Loaded, Center-Guided have been revised and published by MSS.
MSS SP-71 covers gray iron swing check valves with flanged and threaded ends for general-purpose service. In addition, this standard includes, directly or by reference, stipulations on chemical and mechanical properties of materials and dimensions of end connections in common use. Among other updates, this 2018 edition includes SI (metric) and DN equivalencies and increases the flanged-end valve size to NPS 48 (DN 1200), which also impacts end flange requirements for Class 125 full and clear waterway valves.
Additionally, MSS SP-125 covers in-line, internally spring-loaded, centre-guided check valves made of gray iron or ductile iron. These valves, having the feature of limiting fluid flow to one direction only, are intended for use with clean fluids, including potable water, waterworks, and other industrial applications, in horizontal and vertical installations.
The original edition of SP-71 was published by MSS in 1970 and SP-125 was originally published in 2000. The 2018 edition of SP-125 includes a title update. These standards were both developed and continue to be maintained under the consensus of Technical Committee 106, Cast Iron Valves.