Replacement pipe for installation in an existing conduit

Abstract

A form of folded thermoplastic pipe is disclosed for use in repairing a pipeline. Also disclosed are methods and apparatuses especially for installing the thermoplastic pipe in an existing underground pipeline, such as a service lateral, having access from only one end and a bend along its length. The thermoplastic pipe is manufactured in folded form so as to have a folded memory, and spooled for storage in such form. The folded pipe is reheated to make it pliable for installation, and is pulled into the lateral from the access opening using a cable-and-pulley arrangement anchored temporarily at the intersection of lateral and main pipelines. When the folded pipe is installed in the lateral, it is rounded and cured in its rounded shape by passing steam under pressure through 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 it full length, or by an inflatable plug. The inflatable plug may be folded within the thermoplastic pipe before the pipe's insertion and then inflated to plug the leading end of the new pipe after its insertion. Alternatively, the 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 rounding and expansion of the remainder of the new pipe.