ASME B16.21 pdf download Nonmetallic Flat Gaskets for Pipe Flanges 1 SCOPE This Standard covers types, sizes, materials, dimen- sions, tolerances, and markings for nonmetallic flat gas- kets. These gaskets are dimensionally suitable for use with flanges described in the referenced flange standards. 2 GENERAL 2.1 Relevant Units This Standard states values both in SI (metric) and U.S. Customary units....