Method for installing a replacement pipe in an existing conduit

Abstract From the Canadian patent

A substantially rigid thermoplastic pipe manufactured, in a flattened and folded form so as to have a memory in this condition is stored in such form, heated to make it pliable for installation and positioned in an existing pipe. The new pipe is rounded by placing heated fluid in the passages along the folds of the pipe while its leading end is restricted. The leading end may be restricted by an end clamp which enables a hot fluid to pass completely through the pipe and thus heat its full length or by, an inflatable plug. Alternatively an inflatable plug may be, propelled to the leading end of the new pipe after its insertion and then fully inflated to block such end and thereby enable full …