PROCESS FOR PRODUCING CORRUGATED MULTI-LAYER TUBING HAVING LAYERS OF DIFFERING PLASTIC CHARACTERISTICS

摘要

A method for producing polymeric tubing (20) which is resistant to permeation by organic material contained therein which has at least one region defined by a plurality of outwardly extending annular ridges. In this method polymeric material having a first outer diameter and composed of at least three overlying polymeric layers is introduced into a mold device upon exit of the tubular polymeric material from a suitable extrusion device. The mold surface of the mold device has at least one region defined by an annular depression (28) in an essentially cylindrical surface. Once the tubular material (20) is intruduced, it is expanded to a second outer diameter such that the tubular material (20) deformably contacts the mold surface. The corrugated tubular material then exist the mold device after completion of the expansion step.