Patent ID: 7472725

Claim:
A heat-insulated conduit, having at least one internal tube, a heat-insulating layer based on polyurethane foam and surrounding the at least one internal tube, a film surrounding the heat-insulating layer, and a corrugated external tube made of thermoplastic, characterized by the following features: (a) the heat-insulating layer being made of a partially open-cell polyurethane foam having an elongation at breakage of more than 15%; (b) an elastically deformable intermediate layer made of a soft plastic foam between the heat-insulating layer and the film, the intermediate layer being adhesively bonded at least to the film; and (c) the external tube provided with corrugations having a corrugation depth from 5/D to 12/D and a corrugation spacing from 10/D to 25/D, where D is the outside diameter of the external tube measured across the corrugation peaks.