| 摘要 |
A method and apparatus for expanding a replacement thermoplastic pipe installed within an existing conduit is provided. A pipe expansion apparatus having a flexible substantially cylindrical bladder and a relief valve to inflate the bladder to a predetermined gauge pressure and allow fluid to exit the expansion apparatus and fill and pressurize the area behind the apparatus is inserted within the collapsed pipe. Fluid, such as cold water, is introduced into the apparatus to inflate the inflatable section to conform substantially to the interior diameter and configuration of the existing conduit. As the area behind the expander fills with pressurized fluid, the expansion apparatus is pushed forward, thereby pushing and expanding the replacement pipe up against the interior of the existing conduit. Steam is injected ahead of the apparatus to maintain the replacement pipe in a heated flexible condition. When the fluid introduced into the expander is cold water, the replacement pipe will cool and become rigid almost immediately after it is expanded and significantly reduce stress formation. |
