Secured in Place Gasket for Sealing Plastic Pipelines, Method of Manufacture and Method of Installation

Abstract

A pipe sealing gasket is shown which is designed to be received within a raceway provided within a socket end of a female bell plastic pipe end which is assembled with a mating male pipe end to form a plastic pipe joint. The raceway in the female bell plastic pipe end is preformed during manufacture and the gasket is installed thereafter. The gasket has a rubber body portion which is reinforced by a hard plastic band formed as a series of integral, spaced wedges which are interconnected by a flexible ribbon. The hard plastic band acts to prevent extrusion of the gasket during a variety of pressure conditions as well as preventing displacement during field assembly.

What is claimed is: 
     
         1 . A pipe sealing gasket designed for receipt within a raceway provided within a female bell socket end of a thermoplastic pipe, the female bell socket end being designed to receive a mating male thermoplastic pipe end to form a pipe joint, the gasket comprising:
 a ring shaped elastomeric body having a main body portion formed of rubber which, when viewed in cross section, includes a leading nose region, a lower compression region and a trailing tail region, the leading nose region facing generally towards the female socket end of the pipe once the gasket is inserted within the pipe;   wherein the leading nose region of the main body portion of the gasket is reinforced by a hard plastic band formed as a series of integral, spaced wedges interconnected by a flexible ribbon, the hard plastic band being embedded within the leading nose region of the main body portion of the gasket during gasket manufacture; and   wherein the wedges on the hard plastic band act to prevent extrusion of the gasket from the groove provided in the female bell socket end of the thermoplastic pipe once a spigot end of a mating male pipe is installed to form a pipe joint.   
     
     
         2 . The sealing gasket of  claim 1 , wherein the main body portion of the gasket is formed of a natural or synthetic rubber. 
     
     
         3 . The sealing gasket of  claim 2 , wherein the main body portion of the gasket is formed of a rubber selected from the group consisting of styrene butadiene rubber, ethylene propylene diene monomer rubber and nitrile rubber. 
     
     
         4 . The sealing gasket of  claim 1 , wherein the hard plastic band is formed of a synthetic plastic material having a durometer which is greater than the durometer of the main body portion of the gasket while being flexible enough to allow the gasket to accept inverse curvature during installation into the groove provided in the female, socket end of the thermoplastic pipe. 
     
     
         5 . The sealing gasket of  claim 4 , wherein the synthetic plastic material is a modified polyphenylene ether. 
     
     
         6 . The sealing gasket of  claim 1 , wherein the lower compression region of the gasket includes a series of circumferential engagement grooves for engaging the mating male spigot pipe end. 
     
     
         7 . The sealing gasket of  claim 6 , wherein the main gasket body has an outer bulbous region which is also provided with a series of circumferential engagement grooves for engaging the female socket end of the pipe. 
     
     
         8 . A pipe sealing gasket designed for receipt within a raceway provided within a socket end of a female bell pipe member, whereby fitting the gasket within the raceway allows a mating male pipe having a spigot pipe end to be inserted therein to form a continuous pipe joint, the gasket comprising:
 a ring shaped elastomeric body having a main body portion formed of rubber which, when viewed in cross section, includes a leading nose region, a lower compression region and a trailing tail region, the leading nose region facing generally towards the female socket end of the pipe once the gasket is inserted within the pipe;   wherein the leading nose region of the main body portion of the gasket is reinforced by a hard plastic band formed as a series of integral, spaced wedges interconnected by a flexible ribbon, the hard plastic band being embedded within the leading nose region of the main body portion of the gasket during gasket manufacture, the wedges each having a front edge, a rear edge and opposing side edges, as viewed in cross section, and wherein the opposing side edges slope evenly in the direction of the leading nose region of the gasket; and   wherein hydraulic pressure due to fluid in the pipe acts upon the wedges on the hard plastic band to push the wedges into tighter engagement with the mating male and female pipe members to prevent extrusion of the gasket from the raceway provided in the female bell socket end of the thermoplastic pipe once a spigot end of a mating male pipe is installed to form a pipe joint and the pipe is conveying fluid.   
     
     
         9 . A method of manufacturing a sealing pipe gasket designed for receipt within a raceway provided within a socket end of a female bell pipe member, whereby fitting the gasket within the raceway allows a mating male pipe having a spigot pipe end to be inserted therein to form a continuous pipe joint, the method comprising the steps of:
 providing a mold having a first mold face with a circumferential recess;   placing a hard plastic band formed as a series of integral, spaced wedges teeth interconnected by a flexible ribbon within the circumferential recess in the first mold face, the wedges each having a front edge, a rear edge and opposing side edges, as viewed in cross section, and wherein the opposing side edges slope evenly from the rear edges to the front edges thereof;   providing a second mating mold face;   uniting the first and second mold faces and injecting a rubber compound into the mold recess;   applying heat and pressure to the mold to form a ring shaped elastomeric body having a main body portion formed of rubber which, when viewed in cross section, includes a leading nose region, a lower compression region and a trailing tail region, the leading nose region facing generally towards the female socket end of the pipe once the gasket is inserted within the pipe;   curing the main body portion with the hard plastic band contained therein, whereby the leading nose region of the main body portion of the gasket is reinforced by the hard plastic band, whereby hydraulic pressure due to fluid in the pipe acts upon the wedges on the hard plastic band to push the wedges into tighter engagement with the mating male and female pipe members to prevent extrusion of the gasket from the groove provided in the female socket end of the thermoplastic pipe once a spigot end of a mating male pipe is installed to form a pipe joint and the pipe is conveying fluid.   
     
     
         10 . The method of  claim 9 , wherein the main body portion of the gasket is formed of a natural or synthetic rubber. 
     
     
         11 . The method of  claim 10 , wherein the main body portion of the gasket is formed of a rubber selected from the group consisting of styrene butadiene rubber, ethylene propylene diene monomer rubber and nitrile rubber. 
     
     
         12 . The method of  claim 11 , wherein the hard plastic band is formed of a synthetic plastic material having a durometer which is greater than the durometer of the main body portion of the gasket, while being flexible enough to allow the gasket to accept inverse curvature during installation into the groove provided in the female, socket end of the thermoplastic pipe. 
     
     
         13 . The method of  claim 12 , wherein the synthetic plastic material is a modified polyphenylene ether. 
     
     
         14 . A method of installing a gasket with an embedded reinforcing hard plastic band within a gasket receiving raceway provided within the belled end of a female pipe member, the belled end having a mouth opening which is engageable with a spigot end of a mating male plastic pipe section to form a pipe joint, the method comprising the steps of:
 providing a plastic pipe section having a preformed female belled end opening with a gasket receiving raceway;   installing a sealing gasket within the gasket receiving raceway by bending the gasket to temporarily transformed the gasket from a generally cylindrical shape to a generally elliptical shape, placing the gasket within the gasket receiving groove and releasing the gasket, whereby the gasket returns to the generally cylindrical shape;   wherein the gasket is formed as a ring shaped elastomeric body having a main body portion formed of rubber which, when viewed in cross section, includes a leading nose region, a lower compression region and a trailing tail region, the leading nose region facing generally towards the female socket end of the pipe once the gasket is inserted within the pipe;   wherein the leading nose region of the main body portion of the gasket is reinforced by a hard plastic band formed as a series of integral, spaced wedges interconnected by a flexible ribbon, the hard plastic band being embedded within the leading nose region of the main body portion of the gasket during gasket manufacture, the wedges each having a front edge, a rear edge and opposing side edges, as viewed in cross section, and wherein the opposing side edges slope evenly in the direction of the leading nose region of the gasket; and   wherein hydraulic pressure due to fluid in the pipe acts upon the wedges on the hard plastic band to push the wedges into tighter engagement with the mating male and female pipe members to prevent extrusion of the gasket from the raceway provided in the female socket end of the thermoplastic pipe once a spigot end of a mating male pipe is installed to form a pipe joint and the pipe is conveying fluid.