The service life of polyurethane heating insulation pipe can reach more than 50 years

According to the calculations of relevant departments, double-pipe heating pipes can generally reduce the project cost by about 25% (using FRP as the protective layer) and 10% (using high-density polyethylene as the protective layer).

The thermal conductivity of prefabricated polyurethane direct buried insulation pipe is: λ=0.013—0.03kcal/m?h?oC, which is much lower than other pipe insulation materials commonly used in the past, and the insulation effect is increased by 4~9 times. Furthermore, its water absorption is very low, about 0.2kg/m2. The reason for the low water absorption is that the closed cell rate of polyurethane foam is as high as about 92%. Low thermal conductivity and low water absorption, coupled with insulation layer and high-density polyethylene or FRP protective shell with good waterproof performance outside, changed the situation of "wearing wet cotton jacket" for heating pipelines laid in traditional trenches, and greatly reduced the cost of heating pipelines. The overall heat loss, the heat loss of the heating network is 2%, which is less than the international standard requirement of 10%.

The prefabricated polyurethane direct-buried thermal insulation pipe can play a good anti-corrosion effect because the polyurethane rigid foam insulation layer is tightly bonded to the outer skin of the steel pipe, which isolates the infiltration of air and water. At the same time, its foam cells are closed, and its water absorption is very small. Both high-density polyethylene shell and glass fiber reinforced plastic shell have good anti-corrosion, insulation and mechanical properties. Therefore, the outer skin of the working steel pipe is difficult to be corroded by external air and water. As long as the water quality inside the pipeline is well treated, according to foreign data, the service life of prefabricated polyurethane direct-buried insulation pipes can reach more than 50 years, which is 3 to 4 times longer than that of traditional trench laying and overhead laying.

Directly buried heating pipes do not need to build huge trenches, but only need to bury the insulation pipes underground, thus greatly reducing the land occupation of the project, reducing the amount of earthwork excavation by more than 50%, and reducing the amount of civil construction and concrete 90%. At the same time, the processing of the insulation pipe and the on-site trenching are carried out in parallel, and only on-site joints are required, which can greatly shorten the construction period. Due to the reduction of transportation of bricks, cement, gravel, residual soil, etc., the emission of vehicle exhaust, dust, and noise during the construction process is reduced, thereby protecting the environment.

At present, the prefabricated polyurethane direct-buried thermal insulation pipes produced outside of China are all equipped with leakage alarm lines. Once leakage occurs somewhere in the pipeline, through the conduction of the alarm line, the water seepage of the thermal insulation pipeline can be displayed on the special detection instrument. , The exact location of the leak and the size of the leak, so as to notify the seepage inspection personnel to quickly deal with the leaking pipe section and ensure the safe operation of the heating pipe network. Domestically produced insulation pipes are not equipped with leakage alarm lines at present, and this gap needs to be filled.

Summary: In short, prefabricated polyurethane direct buried insulation pipes not only have advanced technology and practical performance that are difficult to match with traditional trenches and overhead laying pipelines, but also have significant social and economic benefits, and are also powerful measures for heating and energy saving. The adoption of directly buried heating pipeline technology marks that the development of China's heating pipeline technology has entered a new starting point. With the further improvement and development of this advanced technology, it is imperative to directly bury heating pipelines instead of trenches and overhead.