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US 4,287,223 AGranted
Covering a steel pipe having a welding seam with a thermoplastic coating
AssigneeMannesmann Aktiengesellschaft
InventorsKarl-Heinz Hackert, Helmut Blume
Life of this patent
Estimating the term…
Abstract
A steel pipe with a thermoplastic cover has the coverage of a welding seam reinforced by hot air heating the cover along the plastic and extruding a strip of similar plastic thereon, followed by cold water spray cooling. The pipe is centered as to the position of the welding seam vis-a-vis the heating and extruding equipment during relative longitudinal movement.
Claims6
In a method of covering a steel pipe having a welding seam, with a layer of thermoplastic material, the improvement of heating the layer in the region of the welding seam;
- and
- of extruding a strip of the same thermoplastic material as said layer onto the layer in the heated region above the welding seam to reinforce coverage thereof.
Dependencies are inferred from the claim text.