(1) Working steel pipes: according to the technical requirements of the transmission medium, seamed steel pipes, seamless steel pipes and double-sided submerged arc spiral welded steel pipes are used respectively.

(2) Thermal insulation layer: rigid polyurethane foam.

(3) Protective shell: high-density polyethylene or fiberglass.

(4) Leakage alarm line: When manufacturing high-temperature prefabricated directly buried insulation pipes, alarm lines are embedded in the insulation layer close to the steel pipe. Once leakage occurs somewhere in the pipe, through the conduction of the alarm line, it can alarm on the special detection instrument and display the exact location and degree of leakage, so as to notify the maintenance personnel to quickly deal with the leaking pipe section and ensure the safe operation of the heat network. Thermal insulation pipe characteristics High temperature prefabricated directly buried thermal insulation pipe - Advantages 1. It has strong corrosion resistance and waterproof ability, and its comprehensive cost is low. According to the estimation of relevant departments, the double pipe heating pipe can generally reduce the project cost by about 25% (using glass fiber reinforced plastic as the protective layer) and 10% (using high-density polyethylene as the protective layer).