Underground long distance heating pipe - has insulating and protective layers of bitumen, glass wool, metal and rolled crepe

摘要

The underground heating pipe consists of an inner steel conduit, coated with a thin layer of bitumen. This is overlaid with a thick insulating jacket of glass wool. A sheet metal tubular shell encloses the glass wool, and there is a film of bitumen around this, with an outer finishing covering of rolled crepe paper or jute. The uninsulated ends of the steel tube are covered with detachable synthetic resin caps. The finished pipe is embedded in sand during laying, and may be welded to the foundation. This is feasible due to the flexibility and light weight of the heating pipe, which enables the pipe to compensate for temperature fluctuations.