Non metallic gaskets

Non-metallic gaskets are usually composite sheet materials used with flat-face flanges and raised-face flanges in low-pressure class applications. Non-metallic gaskets are made of arimide fibre, fibreglass, elastomer, Teflon® (PTFE), graphite, etc. Full-face gasket types are suitable for use with flanges with a flat face. Flat-faced gasket types are suitable for use with flanges with raised surfaces.

Flat ring gaskets have no bolt holes. These gaskets are placed inside the flange bolts and around the pipe hole and are usually used on flanges with a raised surface. When used on a flange with a raised surface, the ring gasket is placed on top of the raised surface of the flange. An advantage of ring gaskets is that they can be installed without having to completely dismantle the joint.

A full-face gasket covers the entire surface of the flange. Full-face gaskets are usually used on flanges with a flat face and have bolt holes through which flange bolts can be inserted through the seal. When installing full-face gaskets, the joint must be completely dismantled.

ASME B16.21 contains types, sizes, materials, dimensions, dimensional tolerances and markings for non-metallic flat gaskets.