polyurethane Rigid foam Thermal insulation pipe Installation technology
Polyurethane foam insulation pipe Since the birth of polyurethane synthetic material in the 1930s, it has been rapidly developed as an excellent thermal insulation material, and its application scope is also increasingly wide. It is also widely used in various heating, cooling, oil transportation, steam transportation, etc. due to its simple construction, energy-saving and anti-corrosion effects * * * The Conduit 。
Installation technology of polyurethane rigid foam insulation pipe
Structure overview:
Front floor: working Steel pipe layer
Generally selected according to the design and customer requirements Seamless pipe (GB8163-87) Spiral welded pipe (GB9711-88; SY/T5038-92) and longitudinal welded pipe (GB3092-93). After the steel pipe surface is treated by advanced shot blasting, the steel pipe rust removal grade can reach Sa2 in GB8923-1988 standard, and the surface roughness can reach R=12.5 μ m in GB6060.5-88 standard.
The second layer: polyurethane insulation layer
It is made by injecting the original liquid of rigid polyurethane foam into the cavity formed between the steel pipe and the outer protective layer with a high-pressure foaming machine. It is commonly known as "pipe in pipe foaming process". Its functions are waterproof, thermal insulation and supporting the weight of the heating network. When the temperature of the conveying medium is - 50 ℃ - 120 ℃, rigid polyurethane foam is selected as the insulation layer.
The third layer: high-density polyethylene protective layer
The prefabricated black (color) plastic pipes with a certain wall thickness can protect the polyurethane insulation layer from mechanical hard objects and prevent corrosion and water.
Performance and parameters:
Technical performance unit technology
Capacity Kg/m3 45-60
Thermal conductivity W/m.k 0.016-0.024
Operating temperature ℃ - 90 - 120
Closed porosity% ≥ 97
Water absorption Kg/m2 ≤ 0.2
Oxygen index h ≥ 26
Compressive strength Mpa ≥ 200
Installation technology of polyurethane rigid foam insulation pipe
Advantages:
1. Reduce project cost.
According to the estimation of relevant departments, the double pipe heating pipeline can generally reduce the project cost by about 25% (using glass fiber reinforced plastic as the protective layer) and 10% (using high-density polyethylene as the protective layer).
2. Low heat loss and energy saving.
Its thermal conductivity is λ=0.013-0.03kcal/m · h · oC, which is much lower than other commonly used pipeline insulation materials in the past, and the insulation effect is improved by 4~9 times. Moreover, its water absorption is very low, about 0.2kg/m2. The reason of low water absorption is that the closed cell rate of polyurethane foam is up to 92%. The low thermal conductivity and low water absorption, together 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 traditional trench laying of heat supply pipes "wearing wet cotton padded jacket", * * reducing the overall heat loss of heat supply pipes. The heat loss of the heat network is 2%, less than the standard requirement of 10% for all.
3. Anti corrosion, good insulation and long service life.
As the polyurethane rigid foam insulation layer is closely bonded to the outer skin of the steel pipe, it can isolate the infiltration of air and water and play a good anti-corrosion role. At the same time, its foam pores are closed, and its water absorption is very small. High density polyethylene shell and glass fiber reinforced plastic shell have good anti-corrosion, insulation and mechanical properties. Therefore, the outer skin of working steel pipe is difficult to be eroded by external air and water. As long as the water quality inside the pipeline is well treated, the service life can reach more than 50 years, which is 3~4 times longer than that of traditional trench laying and overhead laying.
4. Pipe insulation. Small land occupation, fast construction, and favorable for environmental protection.
The thermal insulation of directly buried heating pipes does not need to build huge trenches, only need to bury the thermal insulation pipes underground, so * * reduces the project land occupation, reduces the amount of earthwork excavation by more than 50%, and reduces the amount of civil masonry and concrete by 90%. At the same time, insulation pipe processing and on-site trenching are conducted in parallel, and only on-site joints are needed, which can shorten the construction period by more than 50%.
