ASME B16.21 pdf download Nonmetallic Flat Gaskets for Pipe Flanges 1 SCOPE 1.1 General 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. 1.2 Relevant Units This Standard states values both in metric and U.S. customary units. As...