The extrusion line for PVC-U Double Wall Corrugated Pipe is a new research achievement in Zhongyun in the plastic extrusion field. The production of the pipe by direct extrusion is highly efficient and reliable. Because of the excellent design of wall construction, the pipe can ensure the lightest weight in comparison with other constructions. This means the cost of the pipe can be decreased greatly and the pipe's competitive ability can be increased. It is widely used both at home and abroad as it is an easy and reliable coupling without any complex fitting, and replaces the concrete pipe and cast iron pipe. In China, PVC-U double wall corrugated piping is being used extensively to ensure the development of environmental protection during networking of water and sewerage..