(Also known as CIPP Spot Repair, Part Liner, Patch Liner and Short Liner.)
This uses Cured-in-Place-Pipe (CIPP) technology to create a short section of liner to patch a localized defect or joint in a length of pipe
For the repair of a mainline pipe joint or defect, a pull-in-place CIPP section is used to patch a short distance either side of the damage. Patches can be applied in sequence with overlaps to make longer repairs. To avoid future damage to the repair section, the treatment of the ends of the CIPP repair section is important as is the care taken in future pipe cleaning operations. The patch lining material involves typically a fabric of fiberglass impregnated with thermoset resin and cured either by ambient temperature or light (UV-light cured).
Hydrophilic seals can be incorporated with the liner material to avoid the possibility for leakage in any annulus space behind the new liner.
Usually, the resin is mixed and applied to the fabric mat on the surface. A protective foil layer is wound around the packer and the fabric mat is the wound around that. Another protective foil completes the patch and it is secured on the bladder with light windings. The flexible packer is then inserted through a manhole into the existing pipe. It is pulled by hand or winch to the repair position, assisted by a CCTV camera. The packer bladder is then inflated with compressed air. The patch then cures tightly against the host pipe. When fully cured the packer is deflated and removed from the pipe. The CCTV camera is used to confirm the completeness of the repair.
The patch illustrated and described above is based on using an ambient curing resin, which may take in the order of one to two hours to cure. Much faster curing UV resins can be used with a normal curing speed of 7-10 mins with a transparent silicon bladder containing the necessary UV lights.