Special split die is provided on extruder to get two extruded strips. One strip is wound on mandrel to form inner layer of pipe. Mandrel keeps on rotating and extruder moves with computer control to make perfect tubular winding on mandrel with help of HDPE strip. Second strip envelopes PP corrugated tube and then is placed on joint of inner layer strip.
After pipe is cooled to handling temperature, milling of socket and spigot is carried out. Mandrel is then collapsed by special mechanism provided inside mandrel. Pipe is removed from mandrel and is finished by trimming edges. Rubber or electro-fusion wire is fixed on pipe after finishing.