After the heat insulation treatment of spiral steel pipes(SSAW steel pipe), people are accustomed to call them heat insulation steel pipes.The insulation layer of heat insulation steel pipes is filled with rigid polyurethane foam. The quality requirements for the insulation layer of spiral steel pipes are as follows:
1. Polyurethane foam should be free of stains and shrinkage and delamination. Cells should be uniform and fine, and the average cell size should not be greater than 0.5mm.
2. The insulation layer of the spiral steel pipe should be evenly filled with the annular space between the working steel pipe and the outer protective pipe. The sum of the area of voids and bubbles on the cross section of any insulation layer should not exceed 5%, and the size of a single hole in any direction should not exceed one third of the actual insulation layer at the same
3. The density of the polyurethane foam at any position of the insulation layer should not be less than 60kg / m3.
4. The radial compressive strength or relative radial deformation of the thermal insulation layer of the spiral steel pipe is 10% and the compression force should not be less than 0.3Mpa.
5. Water absorption of polyurethane insulation layer should not be greater than 10%.
6. The closed cell ratio of polyurethane foam should not be less than 88%.
7. The thickness of the insulation layer shall meet the design requirements, and the surface temperature of the outer protective tube shall not be greater than 50 ° C during operation.
8. The thermal conductivity of the unaged polyurethane foam at 50 ° C should not be greater than 0.033 [W / (m-K)].The thermal insulation layer of spiral steel pipe is an important part of thermal insulation steel pipe.It is a key link to ensure the temperature of the conveying medium.Polyurethane foam has good mechanical properties and thermal insulation properties.It can normally withstand temperatures of 120 ° C through modification or with Other combinations of insulation materials can withstand temperatures up to 180 ° C. High-quality polyurethane raw materials and rigorous production technology can produce perfect spiral steel pipes.
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