Thermal stability is also an important characteristic of polyurethane prepolymers.

Sep 13,2023


The slow start-up speed of polyurethane prepolymer insulated steel pipes usually occurs in autumn and winter or during morning construction due to sudden temperature drops or too low temperatures. It can be solved by increasing the ambient temperature and the black material temperature. Usually, the temperature of the black material is increased to 30-60 ° C, and the ambient temperature is increased to 20-30 ° C. Polyurethane prepolymer insulation tubes start up quickly. This phenomenon generally occurs in spring and summer or at noon, because the sudden rise in temperature is caused by excessive temperature. Black materials can be cooled with cold water or left outside for natural cooling to avoid direct sunlight. Polyurethane prepolymer insulation tube foam has low strength and soft foam. This phenomenon is caused by the imbalance of the proportion of black and white materials. Appropriately increase the proportion of black materials (1:1-1.05). Note that the specific gravity of the black material should not be too large, otherwise the foam will become brittle and affect the foam performance. Polyurethane prepolymer insulation pipe has become a relatively mature advanced technology in some developed regions abroad. In the past ten years, China's heating engineering and technical personnel have promoted the development of domestic pipe network laying technology to a higher level by digesting and absorbing this advanced technology. The results of more than ten years of practice fully prove that the polyurethane prepolymer insulated pipe laying method has many advantages compared with the traditional trench and overhead laying. The direct buried insulation pipe is tightly combined by the steel pipe conveying the medium, the high-density polyethylene outer casing pipe and the rigid polyurethane foam insulation layer between the steel pipe and the outer casing pipe. This is also the heating project of polyurethane insulation direct buried pipelines in China.