Hot media transport pipe - with protective plastics sheath carrying hollow ribs

摘要

Buried pipe for the transport of hot water, low or high pressure steam (district heating systems) consists of an inner tube, surrounded by a thick layer of heat insulating material, and covered by a protective layer. The protective layer carries on the outside square hollow ribs in a zigzag pattern. The pref material for the protective layer and the ribs is low-pressure polyethylene. The prefd method of mfr is an extrusion of two coaxial tubes which are thermoformed to the required shape. These tubes are embedded in layers of sand which acts as an abutment for the ribs when thermal elongation takes place. The overall elongation of a ribbed tube is thus 10% of a smooth tube.