The commonly used production methods for polyurethane prefabricated buried insulation steel pipes include one-step and two-step methods. Here we see the two-step production process of prefabricated polyurethane insulation steel pipes. When producing polyurethane prefabricated buried insulation steel pipes, it is necessary to determine the thickness of the insulation layer and the specifications of the polyethylene outer protective pipe. There are slight differences among manufacturers regarding the specific specifications of the insulation layer and outer protective pipe corresponding to each