Method for manufacturing a replacement pipe for installation in an existing conduit

摘要

A thermoplastic pipe for installation in an existing conduit is manufactured in folded form and spooled for storage. The pipe is then reheated to make it pliable for installation and pulled into the conduit for lateral periods. Steam under pressure is used to round the installed pipe. The leading end of the replacement pipe may be restricted by an end clamp which enables hot fluid to pass completely through the pipe and heat the full length, or by an inflatable plug which is displaced to the leading end of the replacement pipe after installation. Methods and apparatus for the manufacturing of the pipe include extruding heated thermoplastic pipe material through a die to form a tubular shape, shaping the resulting hot tubular plastic material in the molten state to the folded form and cooling to provide a pipe with a memory for the folded form.