Underground pipe refurbishment via separation of expanded longitudinal cut

Abstract

A method for refurbishing an existing host pipe, in which an in-situ longitudinal cut is made in the interior wall of a subterranean host pipe. An expansion tool is moved along a path inside the host pipe, stopping at one or more stations on the way. At each station, responsive to isolated outward radial force from the expansion tool, the interior diameter of the host pipe is increased via separation of the longitudinal cut. A new rigid liner pipe is inserted inside the expanded host pipe to operationally replace the host pipe. In some embodiments, grout is deployed in the annular space between liner pipe and host pipe. Expansion of the host pipe via separation of the longitudinal cut optimizes the refurbishment job and enables the original host pipe, as expanded, to contribute structurally to the refurbished pipe system.

I claim: 
     
         1 . A method comprising:
 making an in-situ longitudinal cut through an interior wall of a subterranean host pipe;   upon completion of the longitudinal cut, introducing an expansion tool into the host pipe and moving the expansion tool along a path inside the host pipe, the path having at least one station at which the expansion tool stops, the expansion tool having expansion and retraction modes, the expansion tool adapted to generate isolated outward radial force when in expansion mode;   expanding the host pipe using the expansion tool at each station to increase an interior diameter of the host pipe a predetermined amount via separation of the longitudinal cut through the interior wall; and   inserting a rigid liner pipe inside the host pipe.   
     
     
         2 . The method of  claim 1 , in which an annular space is formed between the liner pipe and the host pipe, the method further comprising:
 at least partially filling the annular space with grout.   
     
     
         3 . The method of  claim 1 , further comprising, prior to making the longitudinal cut, cleaning the host pipe and removing interior debris therefrom. 
     
     
         4 . The method of  claim 3 , further comprising:
 capturing an image of an internal condition of the host pipe immediately after said cleaning step.   
     
     
         5 . The method of  claim 1 , further comprising:
 capturing an image of an initial internal condition of the host pipe on at least one occasion selected from the group consisting of (1) before said expanding step and (2) after said expanding step.   
     
     
         6 . The method of  claim 2 , further comprising:
 stabilizing the liner pipe with stabilization measures before at least partially filling the annular space with grout.   
     
     
         7 . The method of  claim 1 , in which the expansion tool is a generally elongate cylindrical expansion tool having an end assembly rotatably connected to an expansion assembly, the expansion assembly including a stationary radial force surface generally opposed to a floating radial force surface, the expansion assembly adapted to generate isolated outward radial force when actuated by displacing the floating radial force surface away from the stationary radial force surface, and in which the expanding step of the method further comprises, at each station:
 stopping the expansion tool;   actuating the expansion assembly until the stationary radial force surface and the floating radial force surface exert isolated outward radial force on opposing portions of the interior wall of the host pipe;   increasing the unobstructed interior diameter of the host pipe via non-destructive plastic separation of the longitudinal cut through the interior wall;   de-actuating the expansion assembly until at least one of the stationary radial force surface and the floating radial force surface disengages from the interior wall; and   rotating the expansion assembly a predetermined rotational displacement.   
     
     
         8 . The method of  claim 7 , in which the end assembly further includes at least two extendable radial stabilizers, and in which the method further comprises, prior to actuating the expansion assembly, extending the radial stabilizers to engage the interior wall of the host pipe and hold the end assembly rotationally immobile. 
     
     
         9 . The method of  claim 1 , further comprising:
 withdrawing the expansion tool from the host pipe before inserting the rigid liner pipe.