Lining appts. for buried pipes - applies plastics material with memory properties, using swaging and extrusion die

摘要

The method is for lining installed pipework (10) with a length of liner pipe (7) made of a plastic, material having the property of memory retention. The liner pipe (7) has an OD greater than the ID of the pipe (10) being relined and is inserted by drawing the lining pipe first through a swaging/extrusion die (3) which is fitted to one open end of the installed pipe. The lining pipe is drawn through the die (3) under tension and this process reduces the OD by 15% and this allows a clear passage for the lining pipe. When the tension on the liner pipe is released memory induced expansion occurs and creates a suitable fit between the mating dia. of the two pipes. This memory induced change occurs at normal atmospheric pressure and at the ambient temp. of the pipework.