Patent ID: 7410174

Claim:
A self-restrained pressure gasket for insertion within a circumferential recess provided in a bell end opening of a female ductile iron pipe capable of both joining and sealing the female ductile iron pipe to a mating male ductile iron pipe having an interior surface and an exterior surface to create a sealed pipe joint, the gasket comprising: an annular gasket body made of a resilient elastomeric material, the annular gasket body having an inner circumferential region and an outer circumferential region, the inner circumferential region having a circumferential recess located thereon; a relatively rigid split ring located on the inner circumferential region of the gasket body within the circumferential recess of the gasket body, the ring having an inner circumferential surface, an outer circumferential surface and one opening at one circumferential location which creates one overall gap between opposing faces of the ring so that the opposing faces of the ring are spaced apart by a predetermined distance when the gasket is in a relaxed state, wherein the predetermined distance between the opposing faces of the ring which creates the overall gap in the ring can vary from about 1/32 to about ¼ of the total inner circumferential region of the gasket body; at least one row of gripping teeth located on the inner circumferential surface of the relatively rigid ring for engaging selected points on the exterior surface of the mating male iron pipe; wherein the overall gap between the opposing faces of the relatively rigid ring is at least partly filled with a mass of rubber having opposite end regions which form a rubber partition between the opposing faces of the ring, and wherein the opposing faces of the relatively rigid ring are spaced apart from at least one of the rubber end regions by a secondary gap in a relaxed state prior to assembly of the pipe joint; and wherein the overall gap in the ring closes by a predetermined amount as the pipe joint is assembled, the distance between the opposing faces of the ring being selected to prevent the gripping teeth from engaging and biting into the exterior surface of the male iron pipe prematurely before the gasket has been compressed enough to create a seal.