Buried polyurethane insulation from the inside to the outside of the first layer of a three-tier structure: Working pipe layer according to the design and customer requirements generally used in seamless (GB8163-87) spiral welded pipe (GB9711-88; SY / T5038-92) and Longitudinal (GB3092-93). Advanced steel surface after shot blasting process, steel rust rating up to GB8923-1988 standard Sa2 grade, surface roughness up GB6060.5-88 standard R = 12.5 microns. Second layer: polyurethane foam insulation with high-pressure steel pipe machine in the cavity between the outer protective layer is formed in a one-time injection of liquid is made of rigid polyurethane foam, commonly known as "pipe-in-pipe foaming process." First, its role waterproof, two insulation, three heating network is to support the weight. When the transmission medium temperature: -50 degrees -120 degrees, use rigid foam poly ester semicarbazide do insulation. Third layer: high-density polyethylene protective layer of a certain thickness of precast black (yellow) plastic pipe, its role from one protective polyurethane insulation mechanical hard object damage, and second, anticorrosion and waterproof. Buried polyurethane insulation tubes for heating (cooling) on ??the project, its insulation sealing effect is remarkable, for burial, not only to save energy, reduce waste, not land, but also beautify the environment domain. When used in the oil and gas to meet the requirements of long-distance, eliminating the need for operation and maintenance, satisfy frost insulation workers seeking to reduce the heating equipment, and the installation is particularly convenient, shorten the construction period. When used in geothermal hot spring delivery to meet the cooling requirements, to achieve long-distance. Used for irrigation, mining, meet it's freezing cold, heat corrosion requirements. In addition, the pipeline transportation of chemical materials also has broad use of space. In short, polyurethane buried pipe insulation, energy saving, water preservation, freezing cold, beautiful, and many other economic advantages, and it has been in the country has been widely used by the customers. Composed of polyurethane insulation (1) Insulation: using rigid polyurethane foam. (2) protective shell: high density polyethylene or fiberglass. (3) Working steel: According to the technical requirements of the transmission medium were used seam steel pipe, seamless, double-sided spiral submerged arc welded steel pipe. (4) leakage alarm lines: the manufacture of high temperature prefabricated buried pipe insulation, the insulation near the pipe, the 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.