Method of joining plastic pipe

Claim 1

A method of joining polyethylene pipe sections which comprises: 1. heating the internal wall of the end of a high molecular weight polyethylene pipe section at about 470°-530° F. for a period sufficient to soften the wall, 2. heating the external wall of the insert portion of a polyethylene polymer fitting having an annular insert portion with an outer diameter substantially the same as the inner diameter of the pipe section to be joined thereto and a shoulder portion with a larger diameter than the insert portion, at about 470°-530° F. for a period sufficient to soften the external wall surface of the insert, said fitting being formed of a reaction product of a polymer or copolymer of ethylene having a density of 0.940-0.950, with from about 5.0 to about 15.0 percent by weight of the polymer or copolymer of ethylene of a butyl rubber and from about 0.30 to about 2.5 percent by weight of the ethylene polymer or copolymer of a bifunctional phenolic composition having ortho functionality and the para position of the phenol ring substituted with an inert hydrocarbon radical selected from the group consisting of alkyl, aryl, alkyl-aryl and arylalkyl radicals of up to 16 carbon atoms, 3. removing the pipe end and the fitting from the heat source, 4. fitting the insert portion of the coupling into the pipe section so that the edge of the pipe substantially abuts the shoulder portion of the fitting, and 5. crimping the pipe to the insert to cause fusion therebetween.

Claim 2

A method of joining polyethylene pipe sections which comprises: 1. heating the internal wall of the end of a high molecular weight polyethylene pipe section at about 470°-530° F. for a period sufficient to soften the wall, 2. heating the external wall of the insert portion of a polyethylene polymer fitting having an annular insert portion with an outer diameter substantially the same as the inner diameter of the pipe section to be joined thereto and a shoulder portion with a larger diameter than the insert portion, at about 470°-530° F. for a period sufficient to soften the external wall surface of the insert, said fitting being formed of a reaction product of a polymer or copolymer of ethylene having a density of 0.940-0.950, with from about 5.0 to about 15.0 percent by weight of the polymer or copolymer of ethylene of a butyl rubber and from about 0.30 to about 2.5 percent by weight of the ethylene polymer or copolymer of a bifunctional phenolic composition having ortho functionality and the para position of the phenol ring substituted with an inert hydrocarbon radical selected from the group consisting of alkyl, aryl, alkyl-aryl and arylalkyl radicals of up to 16 carbon atoms, 3. removing the pipe end and the fitting from the heat source, 4. fitting the insert portion of the coupling into the pipe section so that the edge of the pipe substantially abuts the shoulder portion of the fitting, and 5. crimping the pipe to the insert to cause fusion therebetween.