Recently, German polystyrene launched a new PP (polypropylene) sewer. This pipe has excellent stiffness, and the deformation rate after one year underground is only 2.3%, which is significantly lower than that of ordinary PP pipes. According to actual test results, the deformation rate of the modified PP sewer pipe is as high as 8%, covering one year. This new type of pipe adopts three-layer technology. The inner and outer layers of the pipe are general PP, and the middle layer PP is a compound composed of PP and magnesium silicate. The cross-linking of the compound can improve the elasticity of the material. The modulus with high stiffness can withstand high loads for a long time. In addition, this three-layer PP sewer connection uses a rubber sealing snap ring. Even if the external force and load cause 30% deformation, the connection socket will not disconnect and separate.