During the injection foaming process of directly buried polyurethane insulation pipe, the quality of polyurethane insulation pipe foam is directly affected by the raw material temperature and the ambient temperature. The ambient temperature should be between 20-30 degrees Celsius. The temperature of polyurethane insulation pipe raw materials can be controlled within the range of 20-30 degrees Celsius or slightly higher. Low temperature, slow chemical reaction, long curing time of foam. If the temperature is high, the chemical reaction will proceed quickly