How are the specifications and parameters of polyurethane buried insulation pipes specified? The outer diameter of polyurethane buried insulation pipes is usually between 20mm and 1420mm, and the appropriate outer diameter can be selected based on the size of the pipeline. A smaller outer diameter is suitable for small pipelines, while a larger outer diameter is suitable for large pipelines. The wall thickness of polyurethane buried insulation pipes is generally between 2.5mm and 25mm, and the insulation layer thickness is not less than 30mm. The thicker the wall, the better the insulation eff