Self restraining gasket and pipe joint
A restraining element for preventing separation of a pipe joint used to join a bell end of a female plastic pipe to the male end of a mating pipe. The restraining element is formed from a compressible body of elastomeric material, the compressible body having a segmented metal ring located therein with gripping teeth for engaging an outer surface of the mating male pipe. The ring segments making up the segmented metal ring are oriented such that the gripping teeth of the ring segments are out of contact with and initially angled away from the outer surface of the male plastic pipe. The teeth of the annular gasket are forced into engagement with the exterior surface of the male plastic pipe as the pipe joint is assembled. The teeth are oriented to allow movement of the male pipe in a first direction relative to the female bell end opening during assembly, but to resist movement in a opposite direction after the pipe joint has been assembled.
1. A pipe joint comprising:
a female plastic pipe having a bell end opening with an annual groove for receiving a sealing gasket, the bell end opening being sized to receive the spigot end of a mating male plastic pipe having an interior surface and an exterior surface;
a self-restrained pressure gasket located within the annular groove provided in the bell end opening of the female pipe capable of both joining and sealing the female pipe to the male plastic pipe, 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;
a segmented ring formed of a plurality of hardened ring segments integrally molded within the material of the gasket body so that the ring segments are at least partially embedded within the resilient elastomeric material, each of the ring segments having an inner circumferential surface, an outer circumferential surface, front and rear end faces and opposing sides;
at least one row of teeth located on the inner circumferential surface of at least selected ones of the ring segments for engaging selected points on the exterior surface of the mating male plastic pipe;
wherein the ring segments are located within the annular gasket body with the inner circumferential surfaces thereof forming an acute angle with respect to the inner circumferential region of the gasket and with respect to the exterior surface of the mating male plastic pipe;
a circumferential gland fitting sized to be received about the outer surface of the mating male plastic pipe, the gland fitting having a forward lip region which contacts and compresses the gasket body as the joint is assembled; and
wherein a plurality of rows of teeth are located on the inner circumferential surface of at least selected ones of the ring segments, the teeth being initially contained within the resilient elastomeric material of the gasket body and thus out of contact with the exterior surface of the mating male pipe, wherein the end faces of the ring segments protrude slightly from the resilient elastomeric material of the gasket body to mate with and contact the forward lip region of the gland fitting.