Polyurethane foam pipe insulation outer protective casing made of high-density polyethylene material extruded, high strength, good corrosion resistance waterproof. Foam insulation, steel pipe and the outer protective tube three closely integrated into one, ≥0.2Mpa shear strength between layers. The main component of polyurethane foam pipe insulation: a protective shell: high density polyethylene or fiberglass. Second, the insulation layer: rigid polyurethane foam. Third, the working pipe: According to the technical requirements of the transmission medium were used seam steel pipe, seamless, double-sided spiral submerged arc welded steel pipe. Fourth, the leakage alarm lines: the manufacture of high temperature prefabricated buried pipe insulation, pipe insulation in the past * layer, embedded alarm line, once the pipeline was leaking somewhere, conduction through the alarm line, will come out in special instrumentation the alarm and shows the exact location and extent of the size of the leak leaking to notify maintenance personnel to quickly deal with leaky pipe to ensure the safe operation of heating network. 

palabras clave: Pipe insulation, polyurethane insulation, steel sleeve steel pipe insulation,