Polyurethane insulation pipe is composed of high-density polyethylene outer sheath, polyurethane rigid foam layer and seamless steel pipe or spiral steel pipe. Also known as&quo; Pipe in pipe;, There are one-step and two-step production methods. The commonly used method is the two-step method, and for those with lower cost and engineering requirements, the one-step method can be used for production. The insulation layer density of polyurethane insulation pipes is between 60kg per cubic meter and 80kg per cubic meter