ASME B16.1-1998

This Standard for Classes 25, 125, and 250 Cast Iron Pipe Flanges and Flanged Fittings covers: (a) pressure-temperature ratings, (b) sizes and method of designating openings of reducing fittings, (c) marking, (d) minimum requirements for materials, (e) dimensions and tolerances, (f) bolt, nut, and gasket dimensions and (g) tests.