MSS - Manufacturers Standardization Society of the Valve and Fittings Industry.
Scope
This MSS Standard Practice applies to the spot facing for U.S. customary (inchseries) bolting of pipe flanges in bronze@ gray iron@ ductile iron@ or steel when cast integral with valves and fittings@ as well as the companion flanges@ when so required by the standard for the product. This Standard Practice also applies to the spot facing for (SI) metric bolting used in bolted joints not covered by the referenced flange standards herein.