Polyurethane-foamed prefabricated directly-buried insulated composite plastic pipe with high-density polyethylene outer sheath (PERT-II type prefabricated directly-buried insulated pipe)

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The PERT-II type thermal pipe is also known as the PERT-II type pre-fabricated buried insulation pipe. Its full name is high-density polyethylene outer protective tube with polyurethane foam insulation – a pre-fabricated buried insulation composite plastic pipe, which is formed by the close combination of a high-density polyethylene outer protective tube, a polyurethane foam insulation layer, and an inner working tube. a. Outer protective tube: The outer layer of the PERT—II type precast buried pipe is made of high-density polyethylene tube ； b. Insulation layer: Rigid polyurethane foam plastic is used. To create a strong, unified structure among the heat-resistant polyethylene (PERT-II) pipe, the outer protective sleeve, and the insulation layer ； c. Service pipe: Heat-resistant polyethylene (PERT-II) pipe. Advantage 1: Low project cost. According to calculations by relevant authorities, dual-control heating pipelines can generally reduce the project cost by around 25% when a fiberglass-reinforced plastic coating is used, and by about 10% when a high-density polyethylene coating is used. 2. Low heat loss, saving energy. Since directly buried pipes are insulated with rigid polyurethane foam, their thermal conductivity is λ=0.013–0.03 kcal/m·h·℃, which is much lower than that of other insulation materials commonly used in the past; as a result, the insulation efficiency is improved by 4 to 9 times. Furthermore, its water absorption rate is very low, at around 0.2 kg/㎡. The low water absorption rate is due to the high closed-cell content of the polyurethane foam, which is around 92%. The low thermal conductivity and low water absorption, combined with an insulating layer and a high-density polyethylene or fiberglass protective shell with excellent waterproof properties, change the situation in which heating pipes laid in traditional trenches are like those wrapped in wet cotton coats. This reduces the overall heat loss of the heating pipes significantly; the heat loss in the heating network is 2%, which is lower than the international standard of 10%. 3. It has good anti-corrosion and insulation properties, as well as a long service life. Buried insulation pipes provide excellent corrosion protection, as the rigid polyurethane foam insulation layer adheres tightly to the working pipe, preventing the infiltration of air and water. At the same time, its foam pores are all closed, resulting in very low water absorption. High-density polyethylene enclosures and fiberglass-reinforced plastic enclosures both possess excellent corrosion resistance, insulation properties, and mechanical strength. Therefore, the working tube is difficult to be eroded by external air and water. According to foreign sources, the service life of polyurethane insulated pipes can reach over 50 years, which is 3 to 4 times longer than that of traditional pipes laid in trenches or overhead. 4. It requires less space, speeds up construction, and is beneficial to environmental protection. Direct-buried heating pipes do not require the construction of large trenches; instead, the insulated pipes are simply buried underground. This significantly reduces the land required for the project, cutting back earthwork by about 50%, as well as reducing the amount of masonry work and concrete used by 90%. At the same time, the processing of insulation pipes and trench digging on site are carried out in parallel; since only on-site connections are required, the construction period can be reduced by about 50%.