ASME B-16.20 deals with metallic/Semi metallic gaskets for ASME B-16.5 and B-16.47 (Pipe Flanges).
What about gaskets for Orifice flanges, Which standard is used ?
B-16.20 can be used ?
Yes agreed with Pennpiper. Selection of the gasket is related to piping, not the orifice. If you are sizing an orifice flow meter, please follow your site piping standard for gasket selection.