PERT II pre-insulated pipe is divided into 3 layers.
The inner layer is the PERT II pressure pipe, high temperature& stress resistance.
The middle layer is the PU (polyurethane) foam, excellent insulation function, heat conductivity only 0.032W/mK.
The outer layer is the protection layer, made by HDPE thin wall pipe.
The three layers expansion coefficient is similar, combine together tightly. Smart Joint produce the pre-insulated pipe one time, ensuring the good insulation quality and saving the pipe cost.