This Standard covers pressure-temperature ratings, materials, dimensions, tolerances, testing, and making of flanges (similar to those covered in ASME B16.5) that have orifice pressure differential connections. Coverage is limited to the following:
(a) welding neck flanges Classes 300, 600, 900, 1500, and 2500. U.S. Customary units are presented in Mandatory Appendix I.
(b) slip-on and threaded Class 300.
(c) welding neck flanges Class 400 in U.S. Customary units in Mandatory Appendix II.