Construction standard for directly buried insulation pipe and buried polyurethane pipe

1. Reduce project cost.

It is estimated that 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 4-9 times higher. 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 thermal insulation layer and the high density polyethylene or glass fiber reinforced plastic protective shell with good water resistance outside, have changed the situation of traditional trench laying of heating pipes "wearing wet cotton padded jacket", greatly reducing the overall heat loss of heating pipes. The heat loss of the heating network is 2%, less than 10% of the standard requirements.

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 corrosion resistance mechanical performance. Therefore, the outer skin of working steel pipe is difficult to be eroded by external air and water. As long as the medium inside the pipeline is properly handled, according to foreign data, 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. Small land occupation, fast construction and favorable environmental protection.

Directly buried heating pipes do not need to build huge trenches, and the insulation pipes are buried underground, so the project land occupation is greatly reduced, the amount of earthwork excavation is reduced by more than 50%, and the amount of civil masonry and concrete is reduced by 90%. At the same time, the insulation pipe processing and on-site trenching are carried out in parallel, and the on-site joint can shorten the construction period by more than 50%.