(1) working steel pipe: according to the technical requirements of conveying medium, slotted steel pipe, seamless steel pipe and spiral welded steel pipe with double-sided submerged arc welding are adopted respectively.
(2) Insulation layer: rigid polyurethane foam is used.
(3) Protective shell: high-density polyethylene or glass fiber reinforced plastic is used.
(4) Leakage alarm line: When manufacturing high-temperature prefabricated directly buried insulation pipe, an alarm line is buried in the insulation layer close to the steel pipe. Once a leak occurs in a certain part of the pipeline, through the conduction of the alarm line, an alarm can be sent out on a special detection table, and the exact location and degree of the leak can be displayed, so as to inform the maintenance personnel to deal with the leaking pipe section quickly and ensure the safe operation of the heating network. Advantages and characteristics of high temperature prefabricated directly buried insulation pipe
1 has strong corrosion resistance and waterproof ability and low comprehensive cost.
According to the calculation of relevant departments, the double-pipe heating pipeline can generally reduce the project cost by about 25% (using FRP as protective layer), 10% (using high-density polyethylene as protective layer).
2. Low heat loss and energy saving. The heat loss is only 25% of the traditional pipeline.
The thermal conductivity of the directly buried insulation pipe is 0.022kcal/m.h.℃, and the hydrophobicity is 0.03kg/cm &；; sup3
3 Long service life
Proper installation and use can make the service life of the pipe network reach 30-50 years, and the maintenance cost is extremely low.
4. Less land occupation, fast construction and environmental protection.
It can reduce earthwork excavation by more than 50%, civil masonry and concrete by 90%, technical performance unit technical capacity Kg/m3 45-60, thermal conductivity W/m.k 0.0 16-0.024, service temperature-90-+120, and closed pore rate% ≥97 water absorption kg/. The reason of low water absorption is that the closed cell rate of polyurethane foam is as high as 92%. The low thermal conductivity and water absorption, coupled with the insulation layer and the high-density polyethylene or glass fiber reinforced plastic protective shell with good waterproof performance outside, have changed the situation of "wearing wet cotton-padded jacket" in the traditional trench laying of heating pipelines, greatly reduced the overall heat loss of heating pipelines, and the heat loss of heating pipelines is 2%, which is less than 10% required by international standards.
Corrosion resistance, good insulation performance and long service life.
Because the polyurethane rigid foam insulation layer is closely combined with the steel pipe skin, it can isolate the penetration of air and water, and can play a good anti-corrosion role. At the same time, its foaming holes are closed and its water absorption is very small. High-density polyethylene shell and glass fiber reinforced plastic shell have good corrosion resistance, insulation and mechanical properties. Therefore, the outer skin of the working steel pipe is not easy to be eroded by external air and water. As long as the water quality in the pipe is well treated, according to foreign data, the service life of high-temperature prefabricated directly buried insulation pipe can reach more than 50 years, which is 3~4 times longer than that of traditional trench burial and overhead laying.
4. Less land occupation, fast construction and environmental protection.
Directly buried heating pipeline does not need to build a huge trench, but only needs to bury the insulation pipe underground, which greatly reduces the engineering area, reduces the earthwork excavation by more than 50%, and reduces the civil masonry and concrete by 90%. At the same time, the processing of insulation pipe is carried out in parallel with on-site slotting, and the construction period can be shortened by more than 50% only by on-site docking.
High-temperature Precast Directly Buried Insulation Pipe Except China, all directly buried insulation pipes are equipped with leakage alarm lines. Once a leak occurs in a certain part of the pipeline, through the conduction of the alarm line, the accurate position and leakage degree of the insulation pipeline can be displayed on the special detector table, so as to inform the leak detector to deal with the leaking pipe section quickly and ensure the safe operation of the heating pipe network. There is no leakage alarm line at the end of the insulation pipeline produced in China, which needs to be filled up.
In a word, insulation pipe not only has advanced technology and practical performance that traditional trench and overhead pipeline can't match, but also has remarkable social and economic benefits, and is also a powerful measure for heating and energy saving. The adoption of directly buried heating pipeline technology marks that the development of heating pipeline technology in China has entered a new starting point. With the further improvement and development of this advanced technology, it is imperative to replace trench and overhead with directly buried heating pipeline.