District heating pipe - comprises inner and outer non-metallic tubes with compression resistant insulation between them

摘要

A pipe for district heating comprises concentric inner and outer tubes with thermal insulation between them. The inner tube is a platics possessing at least the temp. resistance and strength of cross-linked polyethylene, the outer tube is of non-metallic material having at least the mechanical properties of PVC, while the thermal insulation is of a compression-resistant material at the operating temperatures, of the foam glass or mineral fibre type completely occupying the space between the two tubes. This form of pipe is not susceptible to corrosion particularly when buried and can be made to the diameters normally required for district heating systems.