This standard covers raised-face carbon steel welding neck flanges in NPS 26 through 60 with pressure ratings of Classes 75@ 150@ 300@ 400@ and 600 and in NPS 26 through 48 with a pressure rating of Class 900. It also covers integral flanges for Classes 75@ 150@ and 300@ cast or forged as the integral ends of flanged valves@ fittings@ or nozzle necks.