PE-RT Type II prefabricated direct-buried insulated piping is a high-efficiency composite plastic pipe designed specifically for secondary networks in urban district heating systems; its core structure consists of three layers arranged from the inside out. The innermost layer is a Type II heat-resistant polyethylene (PE-RT II) service pipe that directly conveys the heating medium; it supports a long-term operating temperature of 80°C, withstands low temperatures down to -40°C, and has a design service life of 50 years. The middle layer is a rigid polyurethane foam insulation layer with a density of 60–80 kg/m³, offering excellent thermal insulation performance to minimize heat loss.
The outermost layer is a high-density polyethylene (HDPE) protective casing that provides high mechanical strength, corrosion resistance, and impact resistance, effectively protecting the internal structure while also offering a 50-year service life. These three layers are bonded tightly into an integrated unit through a foaming process, with plastic spacers ensuring the service pipe and outer casing remain concentric, and the insulation layer maintaining uniform thickness. Manufactured in accordance with the CJ/T 480-2015 standard, this product features a smooth inner wall, resistance to scaling, low fluid resistance, and minimal heat loss, making it a mature and reliable solution for replacing steel with plastic in modern district heating systems.