Contech Construction Products Inc.

Other

Hubert M Drossbach

Pipe made from thermoplastic polymeric material and including a transversely corrugated outer wall and a smooth inner wall of constant diameter fusion welded to the inner crests of the corrugations of the outer wall is produced by an improved method involving simultaneous extrusion of two tubes, blow molding of the outer wall and fusion of the two walls while the inner wall is supported by an internal shaping and cooling mandrel. Even when the polymeric material is polyvinyl chloride, good fusion welds and lack of brittleness are achieved by the manner in which extrusion is carried out, control of the location at which the fusion welds are established, and the extrusion formulation. The finished pipe is characterized by the fact that, when the fusion welded areas have been cut for inspection, no line of demarcation between the materials of the two walls can be observed.

Method for producing a double wall pipe

Pipe made from thermoplastic polymeric material and comprising a transversely corrugated outer wall and a smooth inner wall of constant diameter fusion welded to the inner crests of the corrugations of the outer wall is produced by an improved method involving simultaneous extrusion of two tubes, blow molding of the outer wall and fusion of the two walls while the inner wall is supported by an internal shaping and cooling mandrel. Even when the polymeric material is polyvinyl chloride, good fusion welds and lack of brittleness are achieved by the manner in which extrusion is carried out, control of the location at which the fusion welds are established, and the extrusion formulation. The finished pipe is characterized by the fact that, when the fusion welded areas have been cut for inspection, no line of demarcation between the materials of the two walls can be observed.

Apparatus for producing double wall pipe

A perforated corrugated tube of thermoplastic or like material in which the tube is made with radially inwardly extending blisters in the valleys thereof which are sheared off to provide perforations through the valleys of the corrugations, the apparatus and method being characterized in that the perforated corrugated tube is made in a continuous manner by molding the tube with the blisters in a traveling mold and shearing the blisters as the tube emerges from the traveling mold. A further characterizing feature of the perforated corrugated tube herein rendering it useful as for highway drainage and frostproofing purposes, is that it is formed with a smooth walled channel-like bottom portion having upwardly diverging side walls merging with the remaining perforated corrugated portion of the tube.

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Bavaria, Germany

Hubert M Drossbach