Comparison of Coating and Wrapping Process with Tubing-in-Tube Process for Polyurethane Insulated Pipes

From the perspective of material and structure: The three-in-one integration of polyurethane-insulated pipes is achieved through the spray-winding production process. After the polyurethane spray is completed, polyethylene sheets can be wrapped around. As it cools and降温, the polyethylene outer sheath generates a shrinkage force, which increases the shear strength compared to the pipe-in-pipe process, making the overall three-in-one performance of the insulated pipe more reliable. From the perspective of the insulating layer: The spray-winding process does not require an excess of theoretical input materials, saving raw materials; it is less likely to produce unevenness and voids, reducing water absorption and increasing the closed cell rate. From the perspective of the outer protective pipe: The spray-winding process does not need to withstand the pressure generated during the polyurethane foaming process, only considering potential damage to the polyethylene pipe during transportation and construction, with a relatively thin thickness; due to the sheet extrusion of polyethylene and the annular wrapping, it avoids the occurrence of longitudinal cracking.