ASME B16.21 NONMETALLIC FLAT GASKETS FOR PIPE FLANGES
ASME B16.21 covers types, sizes, materials, dimensions, tolerances, and markings for nonmetallic flat gaskets. These gaskets are dimensionally suitable for use with flanges described in the referenced flange standards.
Gaskets shall be packaged with NPS, Class, gasket manufacturer’s name, material designation, thickness, and ASME B16.21 marked or tagged on the package or gasket. At the option of the manufacturer, the DN designation may be included.