Steel sleeve steel pipe insulation, also known as "pipe-in-pipe" which has a "two-step" structure, is made of high density polyethylene outer protective layer of polyurethane rigid foam plastic pipe and steel components. One is by the transmission medium pipe, pipe corrosion and superfine wool coat between the pipe and the jacket filled with a combination of steel pipes, also can be used graphite, calcium silicate tiles shell filled with polyurethane foam and composite. Steel casing (steel sleeve steel) buried technology is a waterproof, leakproof laying of new technologies, impermeability, compression and fully enclosed, is a major breakthrough Buried technology used in high water table areas. Steel sleeve tight waterproof steel pipe insulation characteristics of reliability, in addition to have good mechanical strength, high strength steel casing due to the use of welded connections, waterproof sealing performance reliability is very high, in addition, its high temperature performance also other outer protective tube can not be compared. In high water table areas, to ensure groundwater does not affect the normal operation of the steam buried pipe outer protective layer is preferably made of sturdy, airtight steel shell. 1, waterproof 2, high temperature, high pressure, for medium temperature 350 ℃, pressure 2.5Mpa 3, low heat consumption, heat better than any conventional insulation mode 4, corrosion resistance, high strength coating, easy to destroy 5, Long life, up to 30-50 years of life after installing heating cable insulation test immediately insulation layer construction installation, and pay attention to the following points: the material used in insulation, thickness and specifications comply with the design requirements. Construction insulation materials must be dry. Plus waterproof outer insulation layer should cover. When the insulation layer construction to avoid injury band. After the insulation layer construction should be carried out immediately on the heating cable insulation test. Additional warning labels in insulation marked "there are band" more must be marked with the location of all the accessories.