Method and apparatus for producing a smooth-lined corrugated pipe.

摘要

A smooth, plastic-lined corrugated pipe (10) having an intermediate layer of plastic foam (16). The pipe is made by internally coating a corrugated pipe (12) with a foaming mixture and pressing an expandable cylinder of plastic sheet liner (14) against the foaming mixture until the foam solidifies. An expandable mandrel apparatus presses the plastic sheet liner (14) into position.