This Standard covers flanges (similar to those coveredin ASME B16.5) that have orifice pressure differentialconnections. Coverage is limited to the following:
(a) welding neck flanges Classes 300, 600, 900, 1500,and 2500. U.S. Customary units are presented inMandatory Appendix I.
(b) slip-on and threaded Class 300.
(c) welding neck flanges Class 400 in U.S. Customaryunits in Mandatory Appendix II.