The screw is the double-stage pressure reduction type, with special elements to promote the mixing plasticization, coordinated with the highly precise temperature control and high torque, the line can use full recyclable material. The two machines combined type feeding, spiral rotation foamed and high efficiency compound crafts ensure a high quality product. The special plastic and steel compounding technology ensures a reliable compounding, which highly enhances the pipe performance. The adjustable extruder frame is easy and flexible to operate. The PLC automatic control system is reliable and convenient for maintenance.