MSS SP-9-2018 applies to the spot facing for U.S. customary (inch-series) bolting of pipe flanges in bronze, gray iron, ductile iron, or steel when cast integral with valves and fittings, as well as the companion flanges, when so required by the standard for the product.
This Standard Practice also applies to the spot facing for SI (metric) bolting used in bolted joints not covered by the referenced flange standards herein.