Prefabricated direct-buried polyurethane insulation steel pipe: production and processing range φDN20—ΦDN2400
A good insulation material should have low thermal conductivity; it does not deteriorate when exposed to moisture, has good heat resistance, does not corrode metals, is light in weight and has many voids; it has a certain mechanical strength and is not damaged when subjected to external forces; it is easy to process and cost Low-cost and other features. Commonly used insulation materials include: expanded perlite and its products, glass wool and its products, rock wool products, microporous calcium silicate, aluminum silicate fiber products, foam plastics, foamed asbestos, etc.
The high-temperature prefabricated direct-buried heat preservation pipe is composed of steel pipe, glass fiber reinforced plastic inner sheath, and glass fiber reinforced plastic shell. It is characterized by that it also includes a high temperature resistant thermal insulation layer, a lubricating layer, and elastic seals. The utility model effectively solves the problems of heat preservation, sliding lubrication and waterproofing of the exposed pipe ends of the prefabricated direct-buried heat preservation pipe used for high temperature heat transmission at 130°C to 600°C in central heating. The high-temperature prefabricated direct-buried insulation pipe is mainly composed of four parts.
(1) Working steel pipe: Seam steel pipe, seamless steel pipe, double-sided submerged arc spiral welded steel pipe are used according to the technical requirements of the conveying medium.
(2) Insulation layer: use rigid polyurethane foam.
(3) Protective shell: use high-density polyethylene or glass fiber reinforced plastic.
(4) Leakage alarm line: When manufacturing high-temperature prefabricated direct-buried insulation pipes, an alarm line is embedded in the insulation layer close to the steel pipe. Once a leak occurs in a certain part of the pipe, the alarm line can be used in the special detection instrument The upper alarm will show the exact location of the water leakage and the extent of the leakage, so that maintenance personnel can be notified to quickly deal with the leaking pipe section and ensure the safe operation of the heating network.
1. Reduce project cost. According to calculations by relevant departments, dual-pipe heating pipes can generally reduce the project cost by about 25% (using FRP as a protective layer) and 10% (using high-density polyethylene as a protective layer).
2. Low heat loss and energy saving. The thermal conductivity of the high-temperature prefabricated direct-buried thermal insulation pipe is: λ=0.013-0.03kcal/m•h•oC, which is much lower than other commonly used pipeline thermal insulation materials in the past, and the thermal insulation effect is increased by 4 to 9 times. Moreover, its water absorption rate is very low, about 0.2kg/m2. The reason for the low water absorption rate 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 glass fiber reinforced plastic protective shell with good waterproof performance, has changed the traditional "worn jacket" condition of heating pipes laid in trenches, and greatly reduced the heat supply pipes. The overall heat loss, the heat loss of the heating network is 2%, which is less than the international standard requirement of 10%.
3. Anti-corrosion, good insulation performance and long service life. The high-temperature prefabricated direct-buried insulation pipe is tightly bonded to the outer skin of the steel pipe due to the polyurethane rigid foam insulation layer, which isolates the infiltration of air and water, and can play a good anti-corrosion effect. At the same time, its foaming cells are closed, and the water absorption is very small. Both HDPE shell and FRP shell have good anti-corrosion, insulation and mechanical properties. Therefore, the outer skin of the working steel pipe is hard to be corroded by outside air and water. As long as the internal water quality of the pipeline is treated well, according to foreign information, the service life of high-temperature prefabricated direct-buried insulation pipes can reach more than 50 years, which is 3 to 4 times longer than the service life of traditional trench laying and overhead laying.
4. It occupies a small area, and the construction is fast, which is beneficial to environmental protection. Directly buried heating pipelines do not need to build huge trenches, but only need to bury thermal insulation pipes underground, thus greatly reducing the project area, reducing the amount of earth excavation by more than 50%, and reducing the amount of civil masonry and concrete by 90%. At the same time, insulation pipe processing and on-site trenching are performed in parallel, and only on-site joints are required, which can shorten the construction period by more than 50%. High temperature prefabricated direct buried insulation pipe
5. Safety: All high-temperature prefabricated direct-buried insulation pipes produced outside of China are equipped with a leakage alarm line. Once a leak occurs in a certain part of the pipeline, the transmission of the alarm line can indicate the leakage of the insulation pipe on the special detection instrument. , The exact location of the water leakage and the size of the degree of leakage, so as to notify the inspector to quickly deal with the leaking pipe section and ensure the safe operation of the heating pipe network. In short, the high-temperature prefabricated direct-buried thermal insulation pipe not only has advanced technology and practical performance that are incomparable with traditional trenches and overhead pipelines, but also has significant social and economic benefits, and is also a powerful measure for heating and energy saving. The use of directly buried heating pipeline technology indicates 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 to replace trenches and overhead。