VERFAHREN UND VORRICHTUNG ZUM EINBAU EINES NEUEN ROHRS IN EINE VORHANDENE, UNTERIRDISCHE LEITUNG

摘要

A thin, flexible tubular membrane provides a heat containment tube 16 for inserting into and inflation within an underground conduit 10 to be repaired. Folded rigid thermoplastic pipe 22 is inserted into the tube 16 while hot and flexible. The tubular membrane 16 is pressurized to exclude unwanted fluids from within the existing conduit 10. Hot steam is injected into the tube 16 to heat the pipe 22 full-length externally and internally until flexible. The pipe 22 is then rounded and expanded against the walls of the conduit 10 with the tube 16 therebetween. The rounding and expanding of the pipe 22 is carried out progressively by moving a plug (Fig 5) through the pipe 22 and by injecting hot steam under pressure behind the plug. Methods and means for heating the pipe 22 during insertion (Figs 12-15); for repairing short sections of conduit using a comparable section of the pipe (Fig 17), an inflatable bladder and a heat containment tube (Fig 16); for interconnecting and sealing newly installed thermoplastic pipes in a main conduit and intersecting service conduit (Figs 7-9); and for relieving longitudinal stresses in the thermoplastic pipe after installation (Fig 6), are also disclosed. <IMAGE>