On November 28, 2009, our company's PVC - U super silent drainage pipe project passed the acceptance of the expert group. The project is mainly aimed at the current high-rise building drainage excessive noise problems are common research and development, compared with the traditional cast iron pipe, with light weight, corrosion resistance, water resistance of small, energy conservation, environmental protection, easy installation, long service life, etc. Three-layer co-extrusion technology on the steel tubes, the lining design as a combination of a coarse two fine spiral structure, make the water flow along the pipe wall in spiral flow state, and form gas column in the middle of the pipeline, reduce the water flow in the pipe wall. At the same time, the tube wall is evenly distributed in the middle, reducing the contact area of the inner and outer wall to achieve the effect of sound insulation and shock absorption. The silencing effect of the tube was 5 ~ 7 decibels lower than normal pipe.