Historical
ASME B16.4-2011
Gray Iron Threaded Fittings: Classes 125 and 250
This Standard for gray iron threaded fittings, Classes 125 and 250 covers: (a) pressure-temperature ratings (b) size and method of designating openings of reducing fittings (c) marking (d) material (e) dimensions and tolerances (f) threading, and (g) coatings.
American Society of Mechanical Engineers [asme]