Bonded Seal Washers

A bonded seal consists of an outer ring of a hard material, typically steel, and an inner ring of an elastomeric material that acts as a gasket. The compression of the elastomer between the faces of the mating parts provides the sealing action. The elastomeric material, typically nitrile rubber, is bonded to the inside of the metal ring, which holds it in place. This structure increases resistance to bursting thus increasing the pressure rating of the seal. Because the bonded seal outer ring itself retains, the gasket material there is no need for a groove. This results in simplified machining, and greater ease of use as, compared to other seals like O-rings. Some designs come with an additional flap of Rubber to help center the ring over the hole. These are called self-centering bonded seal washers.