Importance

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Abstract

A method and apparatus are described, for extruding a thermoplastic protective jacket onto a steel pipe. The pipe is first coated with a layer of epoxy which is partly cured, and then is conveyed through a cross-head extruder where a layer of copolymer or other suitable adhesive is applied. The outermost thermoplastic jacket may be co-extruded with the adhesive layer or laid down onto the pipe as it passes through a second cross-head extruder. Radial pressure is applied to a band of surface about the jacketed pipe which has been cooled to a stage such that the outer surface of the thermoplastic is hardened while the inner portion thereof remains above the softening temperature, thereby achieving good adhesion of the jacket to the pipe, without dislocating or blemishing the thermoplastic protective jacket.

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First Claim