High-temperature pre-insulated buried pipes, due to the tightly bonded polyurethane insulation layer on the outer surface of the steel pipe, effectively隔绝 air and water intrusion, providing excellent corrosion resistance. Additionally, its foam holes are all closed, resulting in minimal water absorption. Both high-density polyethylene and glass fiber reinforced plastic (GFRP) sheathes offer good corrosion resistance, insulation, and mechanical properties. Therefore, the outer surface of the working steel pipe is difficult to be eroded by external air and water. As long as the internal water quality of the pipeline is well-managed, according to foreign data, the service life of high-temperature pre-insulated buried pipes can reach over 50 years, which is 3 to 4 times longer than that of traditional trench or overhead installations. Polyurethane insulated pipes are equipped with leakage alarm lines; in case of leakage at any point in the pipeline, the exact location and extent of the leakage can be displayed on the detection instrument through the alarm line. The manufacturer of steel-steel pre-insulated seamless pipes uses fiber-wrapped GFRP pipes as the transport pipeline, polyurethane as the intermediate insulation layer, and wrapped GFRP pipes as the external pressure protection layer. Buried pre-insulated pipes have two types of external corrosion protection layers: a finished GFRP corrosion-resistant sleeve, and another type is wrapped with glass fiber mesh after the foam is applied, and then coated with GFRP oil.