Insulated pipes are suitable for transporting various media within a temperature range of -50°C to 150°C. They are widely used in centralized heating and cooling systems, hot oil transportation, as well as insulation and refrigeration projects in greenhouses, cold storage facilities, coal mines, petrochemical, and other industries.
Due to the tight adhesion of the polyurethane rigid foam insulation layer to the outer surface of the steel pipe, the insulated pipe effectively blocks the penetration of air and water, providing excellent corrosion protection. Both the high-density polyethylene (HDPE) and fiberglass reinforced plastic (FRP) outer shells exhibit superior corrosion resistance, insulation, and mechanical properties. Additionally, the closed-cell structure of the foam ensures minimal water absorption, making it difficult for the outer surface of the working steel pipe to be corroded by external air and water.
The service life of insulated pipes can reach over 50 years, which is 3 to 4 times longer than traditional trench or overhead installation methods. Compared to other commonly used insulation pipe materials in the past, the cost is significantly lower, while the insulation effect is improved by 4 to 9 times. Furthermore, its low water absorption rate of approximately 0.2 kg/m2 is attributed to the high closed-cell content of the polyurethane foam, which can reach around 92%.
Insulated pipes eliminate the need for large trenches, as they can simply be buried underground, significantly reducing land occupation and excavation volume by over 50%, as well as civil engineering and concrete usage by 90%. Moreover, the processing of insulated pipes and on-site excavation can be carried out in parallel, with only on-site jointing required, thereby shortening the construction period by more than 50%.
Compared to other previously commonly used insulation pipe materials, the cost is much lower, while the insulation effect is enhanced by 4 to 9 times. The low water absorption rate, combined with the low thermal conductivity and the protective shells made of high-density polyethylene or fiberglass reinforced plastic with excellent waterproof performance, changes the traditional "wet cotton jacket" situation of trench-laid heating pipes, drastically reducing the overall heat loss of the heating pipeline. The heat loss of the heat supply network is only 2%, which is less than the international standard requirement of 10%.
In summary, insulated pipes offer excellent corrosion protection, insulation performance, and long service life. The tight adhesion of the polyurethane rigid foam insulation layer to the steel pipe effectively prevents the penetration of air and water, providing robust corrosion resistance. The closed-cell structure minimizes water absorption, while the HDPE and FRP outer shells provide additional protection. With proper water treatment within the pipeline, the service life of high-temperature prefabricated directly buried insulated pipes can exceed 50 years, significantly outperforming traditional trench or overhead installation methods.
