Self Restrained Ductile Iron Fitting

A combination sealing and restraint system for insertion within an annular groove provided within a mouth region located adjacent an end opening of an as-cast ductile iron fitting capable of both sealing and restraining the ductile iron fitting to a mating male pipe having an interior surface and an exterior surface, the sealing and restraint system 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, and wherein the annular gasket body, when viewed in cross section, includes a leading nose region and a radially inwardly slanting sealing surface which forms a lip seal for engaging the mating male pipe end during insertion, the annular gasket body being installed within the annular groove provided in the mouth region of the as-cast fitting so that the outer circumferential region forms a seal with the fitting mouth region and the inner circumferential region forms a sealing surface for a mating male pipe;
• a plurality of metal gripping segments extending outwardly from the annular gasket body at an inclined angle with respect to a horizontal axis of the mouth region of the iron fitting and at a predetermined spacing around the circumference of the annular gasket body;
• wherein the gripping segments are comprised of an inner planar surface and an outer planar surface separated by a thickness, and wherein the inner planar surface has at least an inner row of gripping teeth and an outer row of gripping teeth capable of engaging selected points on the exterior surface of the mating male pipe and apply a gripping force to the exterior surface, and wherein the teeth on the inner row have a greater radial height than the teeth on the outer row;
• and
• wherein the gripping segments are separated by flexible elastomeric extension regions of the gasket body, each of the gripping segments being provided with a shelf region at a base thereof, the shelf regions having openings formed therein which receive mating portions of the resilient elastomeric material of the gasket body, whereby the gripping segments are mechanically secured to the gasket body.

In combination, a sealing and restraint system and a ductile iron fitting, the combination comprising:

• a ductile iron fitting body having an annular an annular groove provided within a mouth region located adjacent an end opening thereof, the mouth region also having an internal stop region formed adjacent the end opening thereof;
• a sealing and restraint element capable of both sealing and restraining the ductile iron fitting to a mating male pipe having an interior surface and an exterior surface, the sealing and restraint system 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 annular gasket body being installed within the annular groove provided in the mouth region of the as-cast fitting so that the outer circumferential region forms a seal with the fitting mouth region and the inner circumferential region forms a sealing surface for a mating male pipe;
• a plurality of rigid gripping segments extending outwardly from the annular gasket body at an inclined angle with respect to a horizontal axis of the mouth region of the iron fitting and at a predetermined spacing around the circumference of the annular gasket body;
• wherein the gripping segments are comprised of an inner planar surface and an outer planar surface separated by a thickness, and wherein the inner planar surface has at least one row of gripping teeth capable of engaging selected points on the exterior surface of the mating male pipe and apply a gripping force to the exterior surface;
• and
• wherein the gripping segments are separated by flexible elastomeric extension regions of the gasket body, each of the gripping segments being provided with a shelf region at a base thereof, the shelf regions having lock regions formed therein which cooperate with mating portions of the resilient elastomeric material of the gasket body, whereby the gripping segments are mechanically secured to the gasket body.

A method of forming a pipe joint, the method comprising the steps of:

• providing a fluid piping system including at least one as-cast ductile iron pipe fitting, previously cast at a foundry, having a mouth region adjacent an end opening thereof, the mouth region having an annular groove therein, the end opening of the fitting being sized to receive a mating male pipe having an interior surface and an exterior surface;
• in a post-casting operation, installing a sealing and restraining system within the annular groove provided in the end opening of the as-cast fitting, the sealing and restraining system having an annular ring-shaped body made at least in part of a resilient elastomeric material, the ring-shaped body having an inner circumferential region and an outer circumferential region, the ring shaped body being installed within the annular groove provided in the mouth region of the as-cast fitting so that the outer circumferential region forms a seal with the fitting mouth region and the inner circumferential region forms a sealing surface for the mating male pipe section;
• wherein a plurality of integrally formed gripping segments are provided for applying a gripping force to a mating male pipe, each having an outer planar surface extend outwardly from the annular gasket body at a predetermined spacing around the circumference of the annular gasket body, the spacing being sufficient to allow the gasket body to be flexed to thereby allow the sealing and restraint system to be installed in the mouth region of the pipe fitting as a post-casting operation;
• and
• wherein the gripping segments are each provided with a shelf region at a base thereof, the shelf regions having openings formed therein which are filled with resilient elastomeric material of the gasket body, whereby the gripping segments are mechanically secured to the gasket body.