The material of the insulation layer is rigid polyurethane foam with a density of 60kg/m3 to 80kg/m3, which fully fills the gap between the steel pipe and the casing, and has a certain bonding strength, so that the steel pipe, the outer casing and the insulation layer are between the three Form a strong whole. Insulation steel pipe foam has outstanding mechanical function and heat insulation function, under normal circumstances, it can withstand temperature of 120℃, after modification or combined with other heat insulation materials, it can withstand temperature of 180℃. The material of the insulation layer is rigid polyurethane foam with a density of 60kg/m3 to 80kg/m3, which fully fills the gap between the steel pipe and the casing, and has a certain bonding strength, so that the steel pipe, the outer casing and the insulation layer are between the three Form a strong whole. Insulation steel pipe foam has outstanding mechanical function and thermal insulation function, under normal circumstances, it can withstand a temperature of 120 ℃, modified or combined with other heat insulation materials, can be heat-resistant insulation steel pipe.

　　1. Anti-corrosion layer: Maintain the outer steel pipe to prevent corrosives from corroding the steel pipe and prolong the service life of the steel pipe.

　　2. Outer-protected steel pipe: It protects the insulation layer from groundwater corrosion, supports the work pipe and can accept certain external loads to ensure the normal operation of the work pipe.

　　3. Polyurethane foam layer: to ensure the temperature of the medium, to ensure that the outer protective tube surface maintains normal temperature.

　　4. Isolation and reflection layer: to ensure that organic foam materials do not enter the inorganic hard high temperature resistant layer; reflect part of the heat of the high temperature resistant layer.

　　5. Inorganic hard thermal insulation layer: high temperature resistance, to ensure the interface temperature between the organic thermal insulation layer and to ensure that the foam is not carbonized.

　　6. Drag reduction layer: to ensure that the working steel pipe expands and contracts freely.

　　7. Working steel pipe: to ensure the normal movement of the conveying medium.