Transition pipe joint

Claim 2

A metal pipe to plastic pipe transition connection comprising: a straight end metal pipe including, form said end, a first internal peripheral surface, a second series of internal grooves extending from said first surface to a third internal circumferential groove; a plastic pipe of cold-extrudable material, a portion of which extends internally within said metal pipe so as to be Coaxial and opposite said first surface, said second grooves and said third groove; and a rigid substantially cylindrical compression sleeve, forced to be coaxial internally about said portion of said plastic pipe, said sleeve, beginning at one end, having sequentially a first external peripheral surface of substantially uniform diameter, a second external peripheral surface of substantially uniform diameter slightly greater than said first surface so as to be of greater interference fit to said plastic pipe than said first surface and oriented so as to extrude said plastic pipe into said second grooves, a third external peripheral surface of substantially uniform diameter slightly greater than said second surface so as to provide interference fit of said plastic pipe and extrude same into said third groove.

Claim 3

A transition connection of claim 1 wherein the length of said sleeve is longer than the total length of said first surface, second grooves and third groove so as to extend, when assembled, beyond the end of said metal pipe.

Claim 4

A connection of claim 1 wherein said second internal grooves are threads.

Claim 5

A connection of claim 3 wherein said threads are round.

Claim 6

A connection of claim 1 wherein said third groove is about 0.010 to 0.020 inch below the maximum diameter of said second grooves.

Claim 7

A connection of claim 1 wherein said plastic pipe is polyethylene.

Claim 8

A metal pipe to plastic pipe transition connection comprising: a straight end plastic pipe being of an extrudable material; a straight end metal pipe including, at said end about which said plastic pipe is received: a first cylindrical portion adjacent said end, a second series of external grooves extending from said first portion to a third circumferential groove, said first cylindrical portion and second grooves being of dimension to cause interference fit with the I.D. of said plastic pipe when fitted thereover; a rigid cylindrical sleeve extending circumferentially about said plastic pipe, said sleeve having a first internal peripheral surface of substantially uniform diameter interference fitted with the O.D. of said plastic pipe so as to extrude said plastic pipe into said second grooves, and said sleeve having a second internal surface of substantially uniform diameter yet of greater interference fit with said O.D. than said first surface to extrude said plastic pipe into said third groove, the length of said first cylindrical portion being proportioned relative to the size of said plastic pipe being used such that it is of sufficient length to prevent cold flow of said plastic pipe from between said rigid cylindrical sleeve and said metal pipe.

Claim 9

A metal pipe to plastic pipe transition connection comprising: a straight end plastic pipe being of an extrudable material; a straight end metal pipe including, at said end about which said plastic pipe is received: a first cylindrical portion adjacent said end, a second series of external grooves extending from said first portion to a third circumferential groove, said first cylindrical portion and second grooves being of dimension to cause interference fit with the I.D. of said plastic pipe when fitted thereover; a rigid cylindrical sleeve extending circumferentially about said plastic pipe, said sleeve having a first internal peripheral surface of substantially uniform diameter interference fitted with the O.D. of said plastic pipe so as to extrude said plastic pipe into said second grooves, and said sleeve having a second internal surface of substantially uniform diameter yet of greater interference fit with said O.D. than said first surface to extrude said plastic pipe into said third groove, the length of said first cylindrical portion being proportioned relative to the size of said plastic pipe being used such that it is of sufficient length to prevent cold flow of said plastic pipe from between said rigid cylindrical sleeve and said metal pipe.

Claim 10

A connection of claim 7 wherein the length of said cylindrical sleeve is longer than the total length of said first surface, said second grooves and said third groove so as to extend, when assembled, beyond the end of said metal pipe.

Claim 11

A connection of claim 7 wherein said second external grooves are threads.

Claim 12

A connection of claim 9 wherein said threads are round.

Claim 13

A connection of claim 7 wherein said third groove is about 0.010 to 0.020 inch below the minimum diameter of said second grooves.

Claim 14

A connection of claim 7 wherein said plastic pipe is polyethylene.