| 摘要 |
In thermally insulated pipelines of the fixed type, that is to say with a rigid foam layer 8 which is attached both to medium pipes 5, 6 and jacket pipes 4, stress- relief joints 7 are incorporated in the medium pipe 5, 6 at a spacing which is smaller than the friction length. The stress-relief joints 7 make possible axial movements 26, 27 of the medium pipe 5, 6. In the regions around the stress-relief joints 7, the foam layer 8 and the jacket pipes 4 are subjected to pressure or tension. The stress- relief joints are coated with lubricant 10. The construction allows the laying of district heating pipes without clamping. A construction of the stress-relief joints 7 is shown. <IMAGE>
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