This Standard covers malleable iron threaded fittings, Classes 150 and 300. It also contains provisions for using steel for caps and couplings in Class 150 for NPS 3⁄8 and smaller. This Standard includes
(a) pressure–temperature ratings
(b) size and method of designating openings of reducing fittings
(e) dimensions and tolerances
Mandatory Appendix I provides table values in U.S. Customary units.