Plastic pipe sealing gasket and process for belling plastic pipe

A method of forming a pipe joint using a pipe sealing gasket designed for receipt within a groove provided within a female socket end of a first section of pipe for forming a seal between an internal surface of the female socket end and a male spigot end of a mating second pipe section, the method comprising the steps of:

• installing a sealing gasket within the groove provided within the female socket end of the first pipe section, the sealing gasket being formed as a ring shaped elastomeric body which, when viewed in cross section, has a central bulbous region formed of a suitable elastomer, the central bulbous region having located therein a planar angled region which bisects the bulbous region at a selected radial location and which extends outwardly from the central region to form a pair of oppositely arranged wing-like flaps, the planar angled region being formed of a dissimilar plastic material;
• wherein the central bulbous region of the sealing gasket forms an oval profile when viewed in cross section, the oval profile having an outer surface region which is adapted to seat within the groove provided in the socket end of a thermoplastic pipe, the oval profile also having an inner surface region which forms a compression seal region for a mating spigot end of a mating thermoplastic pipe during insertion of the spigot end within the mating socket end of the thermoplastic pipe;
• wherein the oppositely arranged wing-like flaps which extend outwardly from the central bulbous region form a V-shaped cavity bounded by a leading and a trailing flap, which cavity receives the inner surface region of the central bulbous region of the gasket, and wherein the leading flap has an outer edge which makes contact with the spigot pipe end during insertion and wipes any dirt present from the spigot end, keeping the dirt from reaching the cavity and the inner surface region which forms a compression seal region for sealing against the spigot end;
• and
• installing the spigot end of one thermoplastic pipe section within the socket end of a second pipe section to form a pipe joint.

A method of installing a gasket in a socket end of a thermoplastic pipe which is used to form a pipe coupling, the method comprising the steps of:

• providing a mandrel with an inner end and an outer end and having an outer working surface;
• installing a gasket at a first circumferential position on the outer working surface;
• heating a socket end of the thermoplastic pipe;
• forcing the heated socket end of the thermoplastic pipe over the working surface of the mandrel and over the gasket and backup collar, whereby the heated socket end of the thermoplastic pipe flows over the gasket to form a retention groove for retaining the gasket;
• cooling the heated socket end of the thermoplastic pipe;
• retracting the cooled socket end of the thermoplastic pipe and the retained gasket from the working surface of the mandrel;
• wherein the gasket is a ring shaped elastomeric body which, when viewed in cross section, has a central bulbous region formed of a suitable elastomer, the central bulbous region having located therein a planar angled region which bisects the bulbous region at a selected radial location and which extends outwardly from the central region to form a pair of oppositely arranged wing-like flaps, the planar angled region being formed of a dissimilar plastic material;
• wherein the first circumferential region provided on the working surface of the mandrel comprises a circumferential groove having opposing sidewalls, and wherein the oppositely arranged wing-like flaps which extend outwardly from the central bulbous region form a V-shaped cavity bounded by a leading and a trailing flap, which cavity receives the inner surface region of the central bulbous region of the gasket, and wherein the flaps each have an outer edge which makes contact with the sidewall regions of the mandrel groove to thereby lock the sealing gasket within the circumferential groove provided on the working surface of the mandrel.