PE-RT Type II prefabricated direct-buried insulated piping is a high-efficiency piping system designed specifically for secondary networks in municipal district heating. Its structure is characterized by a composite "three-in-one" configuration: a carrier pipe, an insulation layer, and an outer protective casing. The inner layer is the carrier pipe, made of Type II heat-resistant polyethylene (PE-RT II); it is capable of long-term transport of hot water at temperatures up to 85°C (with a peak tolerance of 95°C) and exhibits excellent low-temperature impact resistance down to -40°C, alongside advantages such as a smooth inner wall, low fluid resistance, corrosion resistance, and resistance to scaling. The middle layer consists of rigid polyurethane (PU) insulation, bonded tightly to the inner and outer layers via a chemical foaming process, with a density of approximately 60–80 kg/m³, a high closed-cell ratio, and extremely low thermal conductivity; it effectively minimizes heat loss and ensures high energy efficiency. The outer layer is a high-density polyethylene (HDPE) casing that offers superior waterproofing, corrosion resistance, and impact resistance, protecting the internal structure against soil chemicals and mechanical damage. Some products also feature plastic spacers between the carrier pipe and the outer casing to maintain a concentric structure.
Thanks to this design, PE-RT Type II insulated piping offers outstanding performance advantages: excellent thermal insulation with minimal heat loss, resulting in significant energy savings during long-term operation; a design service life of up to 50 years, far exceeding that of traditional steel pipes; exceptional corrosion resistance requiring no additional anti-corrosion treatment, making it suitable for diverse soil environments; and ease of installation-utilizing heat-fusion or electro-fusion connections and allowing for serpentine laying without the need for trenches or fixed anchor blocks, all at a low total cost. Furthermore, the piping materials are non-toxic and environmentally friendly, posing no risk of water contamination, and the system offers excellent hydraulic characteristics. Compliant with the CJ/T 480-2015 standard, this product is becoming an ideal choice for modern district heating systems.