MSS - Manufacturers Standardization Society of the Valve and Fittings Industry.
Scope
This Standard Practice establishes material and dimensional requirements for valve packing@ packing chamber@ packing gland@ packing washer@ bonnet@ and stem as they relate to the total packing assembly. This Standard Practice applies to standard@ special@ and limited Class 150 through Class 4500 (including intermediate classes) ASME B16.34 type steel gate@ globe@ and angle valves designed with rotating/ rising and non-rotating ising stems This Standard Practice applies to valves in which a flexible graphite packing assembly is used as the primary stem-sealing system This Standard Practice does not apply to valves that include a lantern ring as part of its packing system nor to bonnetless valves with split glands.