MSS - Manufacturers Standardization Society of the Valve and Fittings Industry.
Scope
"This Standard Practice covers the dimensions which define the interface between drilling/tapping machine adapters and tapping valves including clearances for the pilot drill and cutter. This ""interface"" or ""connecting joint between tapping machines and tapping valves"" will be abbreviated as ""joint"" in this SP. The positioning recess and mating raised face of the connecting flanges or end connections between machine adapters and tapping valves@ serve to ensure proper alignment of the machine adapter onto the tapping valve without affecting the strength of the joint. Only flanged@ mechanical joint@ push-on@ asbestos cement and radial compression connections are included in this standard. The standard covers dimensions for these special connecting flanges of nominal sizes from NPS 2 through 60 for water and sewerage systems. Pressure and pressure-temperature ratings are beyond the scope of this Standard Practice."