Combination seal and restraint system for plastic pipe

1. A combination seal and restraint system capable of both joining and sealing a female plastic pipe to a mating male plastic pipe having an interior surface and an exterior surface, the seal and restraint system comprising:

a sealing ring formed as an elastomeric body, the sealing ring being integrally installed within a groove formed in a belled end of the female pipe during the manufacture of the belled pipe end;

a companion restraint mechanism for the elastomeric sealing ring which allows movement of the mating male pipe relative to the belled end of the female pipe in a first longitudinal direction but which restrains movement in a second, opposite relative direction, the restraint mechanism comprising a ring shaped housing which is also integrally installed within the belled pipe end during manufacture and which has a circumferential interior region and a companion gripping insert which is contained within the circumferential interior region of the housing, the gripping insert having an exterior surface and an interior gripping surface with at least one row of gripping teeth;

wherein the gripping insert is a ring shaped member having at least one circumferential slit in the circumference thereof which allows the gripping insert to be temporarily compressed and installed within the circumferential interior region of the housing in snap-fit fashion after the ring shaped housing has been integrally installed within the belled pipe end during manufacture of the female pipe;

wherein a removable spacer is temporarily placed in the at least one circumferential slit in the gripping insert, whereby the gripping insert is spread apart an additional, preselected amount once the insert is received within the circumferential interior region of the housing;

wherein the amount the gripping insert is spaced apart is selected to cause the gripping insert to be initially received more closely within the housing circumferential interior region, whereby the teeth of the gripping insert are initially concealed in the housing circumferential interior region.

2. The combination seal and restraint system of claim 1 , wherein the placement of the spacer in the gripping insert prevents the insert from making detrimental contact with an exterior surface of a forming mandrel during subsequent belling operations.

3. A combination seal and restraint system capable of both joining and sealing a female plastic pipe to a mating male plastic pipe having an interior surface and an exterior surface, the seal and restraint system comprising:

a sealing ring formed as an elastomeric body, the sealing ring being integrally installed within a groove formed in a belled end of the female pipe during the manufacture of the belled pipe end;

a companion restraint mechanism for the elastomeric sealing ring which allows movement of the mating male pipe relative to the belled end of the female pipe in a first longitudinal direction but which restrains movement in a second, opposite relative direction, the restraint mechanism comprising a ring shaped housing which is also integrally installed within the belled pipe end during manufacture and which has a circumferential interior region and a companion gripping insert which is contained within the circumferential interior region of the housing, the gripping insert having an exterior surface and an interior gripping surface with at least one row of gripping teeth;

wherein the gripping insert exterior surface has a sloping profile which contacts a mating interior region of the housing, whereby contact with the exterior surface of a mating male plastic pipe causes the gripping insert to ride alone the exterior male surface at an angle while the row of gripping teeth on the gripping insert internal surface engage the exterior surface of the mating male plastic pipe;

wherein the housing has a rear wall region which is substantially perpendicular to a longitudinal axis of the female pipe, the rear wall region being in contact with the elastomeric body of the sealing ring as a mating male pipe is inserted into a mouth opening of the female plastic pipe;

wherein the housing exterior surface has at least one row of biting teeth for biting an internal diameter of the female plastic pipe, the biting teeth being located on a region of the exterior surface which is forward of a vertical central axis of the housing.

4. A combination seal and restraint system capable of both joining and sealing a female plastic pipe to a mating male plastic pipe having an interior surface and an exterior surface, the seal and restraint system comprising:

a sealing ring formed as an elastomeric body, the sealing ring being integrally installed within a groove formed in a belled end of the female pipe during the manufacture of the belled pipe end;

a companion restraint mechanism for the elastomeric sealing ring which allows movement of the mating male pipe relative to the belled end of the female pipe in a first longitudinal direction but which restrains movement in a second, opposite relative direction, the restraint mechanism comprising a ring shaped housing which is also integrally installed within the belled pipe end during manufacture and which has a circumferential interior region and a companion gripping insert which is contained within the circumferential interior region of the housing, the gripping insert having an exterior surface and an interior gripping surface with at least one row of gripping teeth;

wherein the sealing ring and housing are at least temporarily joined at a juncture point prior to being installed within the belled pipe end.

5. The combination seal and restraint system of claim 4 , wherein the juncture point is designed to be severed during the belling operation so that the sealing ring and the housing are separate at the time a pipe joint is made up in a field application.