This standard is intended to cover A. P. I ring joint dimensions for American Standard (A S A )* steel flanges@ (threaded with A. P. I standard line pipe threads! or American Standard thread)@ other sizes of flanges as required@ and rolled@ and slip-on welding and welding neck flanges These ring-joint dimensions are also to be used on steel flanged valves and fittings where connected to ling-joint flanges@ or where ring joints are required in piping connections. This standard also covers ring-joint flange unions for use with A. P. I. tubular goods??@ (line pipe@ casing@ drill pipe@ and tubing). *A S A Standards mentioned herein may be secured from the American Stanards Association@ 29 West 39th St@ NewYork N Y ?? See A P I Stds No -F Threads in Fittings