Product Structure

The product consists of three parts: a steel pipe for transporting media, spray-coated polyurethane rigid foam, and a winding polyethylene outer sheath. It is suitable for transporting hot water with a temperature not higher than 140°C.

Working steel pipes: Seamless steel pipes, spiral welded pipes, and straight seam welded pipes are used; before insulation, mechanical rust removal is required, and the rust removal level is not lower than the Sa2.5 level in GB/T8923.1.

Spray polyurethane insulation layer:Made of fluorine-free fully water-hard polyurethane foaming foam which has zero ozone depletion potential (ODP) and can protect the environment and reduce damage to the ozone layer. Any position’s polyurethane foam density in the insulation layer is not less than 60kg/m³.

Wound polyethylene outer sheath:Using DHPI’s self-owned product modified polyethylene material then shaped by extruding and winding. The modified polyethylene material can have certain reaction with the insulation layers during the extrusion lateral winding process, thereby the bonding force between the outer protective layer and the insulation layer can be improved. Meanwhile, the tensile yield strength of outer sheath is greater than 19 Mpa, features on high mechanical strength and excellent corrosion resistance.

 Performance Characteristics

（1）The core indicators such as product thickness, density, thermal conductivity, closed cell ratio, and water absorption are uniform and consistent, and the overall stability is good.

（2）The axis eccentricity is small, the thermal conductivity is low, and the overall thermal insulation effect is good.

（3）Polyurethane online spraying has high reactivity and good bonding effect with both the steel pipe and the outer sheath. The insulation pipe is less affected by temperature changes and does not produce delamination.

（4）The surface of the insulation layer is smooth, the thickness deviation is small, and the adjustment range is large.

（5）The outer sheath is made of polyethylene winding, with thin and uniform walls, small shrinkage, small deformation and stress, and good overall mechanical properties, which solves the problem of easy cracking of the outer sheath.

（6）No bracket support is required, the heat loss is small, and the "bracket thermal bridge" phenomenon is completely eliminated.

（7）Polyurethane foams immediately after spraying. The foaming situation is clearly visible and the heat released is quickly dissipated, eliminating foam heartburn.