Prefabricated, externally insulated district heating pipe - has two layers of bituminous insulation, inner layer being partly molten in use

摘要

A steel inner pipe (2) is surrounded by an inner sleeve (4) of bituminous material. The thickness of the inner sleeve is between one and ten times, e.g. three times, the thickness of the liq. zone of the bituminous material. The liq. zone is defined as the zone in which the temp. is above the Wilhelm melting point of the material. The inner sleeve is surrounded by an outer sleeve (6) of compressed, thermally insulating lightweight material, pref. bituminised particulate material.