The polyurethane direct-buried thermal insulation pipe has excellent overall performance, and strictly implements the shot blasting treatment of the outer surface of the steel pipe and the corona treatment process on the inner surface of the outer protective pipe to further improve the bonding performance of the thermal insulation pipe.

The insulation material of the polyurethane insulation pipe is a rigid polyurethane foam with a density of 60kg/m3 to 80kg/m3, which fills the gap between the steel pipe and the casing, and has a certain bonding strength, making the steel pipe, the outer tube and the insulation layer one of the three Form a solid whole. The foam of the polyurethane insulation pipe has good mechanical properties and thermal insulation properties. It can withstand a temperature of 120°C in a normal environment, and can withstand a temperature of 180°C through modification or combination with other insulation materials.

The polyurethane insulation pipe is divided into three layers from the inside to the outside:

The first layer: Working steel pipe layer: According to the design and customer requirements, seamless steel pipes, spiral steel pipes and straight seam steel pipes are generally selected. After the surface of the steel pipe is treated by the advanced shot blasting process, the rust removal grade of the steel pipe can reach the Sa2 level in the GB8923-1988 standard, and the surface roughness can reach the R=12.5 micron in the GB6060.5-88 standard.

The second layer: Polyurethane insulation layer: a high-pressure foaming machine is used to inject rigid polyurethane foam plastic stock solution into the cavity formed between the steel pipe and the outer sheath at one time, which is commonly known as "tube-in-tube foaming".

The third layer: high-density polyethylene protective layer: pre-made black or yellow polyethylene plastic pipe with a certain wall thickness. One of its functions is to protect the polyurethane insulation layer from being damaged by mechanical hard objects, and the other is to prevent corrosion and waterproof.

Polyurethane composite material has the characteristics of fine cells, good flow, sufficient toughness and high strength. It has a great physical tolerance and can meet various production process requirements of customers. It is suitable for 1020, 820, 630, 720, 529, 325, 159, etc. On pipelines of different sizes and specifications, the density is evenly distributed. At the same time, it is suitable for low-temperature construction, and the special product can withstand low temperature of minus 200 ℃ for a long time.