First, the product scope of the transmission medium: hot water, air withered aqueous medium pressure: ≤1.6MPa Medium temperature: ≤120 ℃ Work environment: underground soil Second, the product structure of the steel pipe insulation, cyanide preservatives, polyurethane rigid foam insulation and high-density polyethylene outer tube is coupled prefabricated pipe. Third, the product material technical requirements, transmission fluid with seamless steel pipe (GB8163-99) or pressurized fluid transfer sheet with spiral submerged arc welding pipe (SY5036-83), also should request the use of brass or stainless steel Other pipe and other materials. 2, anti-corrosion materials used cyanide as the underlying corrosion preservatives polyurethane prefabricated buried pipe insulation structure from the inside to the outside can be divided into three levels: ◆ The first layer is the transmission medium of the work of the core tube, successfully resolved the waterproof anti-leak difficult. Made with steel outer protective layer having a high strength core pipe is generally made of seamless pipe (GB8163-87) spiral pipe (GB9711-88; SY / T5038-92) and Longitudinal (GB3092-93) and galvanized steel and PPR and other materials; according to different requirements of users choose, the core tube diameter is [φ22,25,32,38,45,57,76,89,108,133,159,219,273,325,377,426, 478,529,630,720,820,920,1220] ◆ The second layer is made of polyurethane foam insulation or composite insulation materials, insulation thickness [its] ◆ 30-150mm third layer is the outer protective layer High-density polyethylene jacket pipe, glass steel and anti-corrosion steel Pipe.