DN1600 polyurethane rigid foam prefabricated buried insulation pipes for hot water transportation belong to the large diameter insulation pipeline series. The working steel pipe is a steel pipe with an outer diameter of 1620mm. The thickness of the polyurethane hard foam insulation layer in the middle is 65 millimeters, and the outer protective sleeve is made of high-density polyethylene material. The standard size of the outer sleeve is 1780 millimeters, with a thickness of 15 millimeters.