CIPP Inversion: The Liner tube is soaked with a two-part resin and then inserted into the pipe using air pressure, inverting the liner inside out until the liner reaches the sewer main collection pipe. The liner is designed to tightly fit the host pipe annular spaces and gaps. A calibration tube is inserted to ensure the liner remains in place during the curing process. Dry Steam is introduced in order to raise the temperature of the liner to cure or “harden” the liner against the host pipe. The result is essentially a pipe within the existing and failing host pipe.
Pull-in-Place or Inversion
The Benefit of the Inversion Process is that there is a continuous liner covering the entire host pipe, the liner has smooth interior and no joints. It effectively reduces infiltration and leaks in pipelines without digging.
The lateral connections draining into or out of the host pipe are then “reinstated”, or opened up by mechanically or manually cutting through the cured or hardened liner, smoothing the edges to ensure proper flow of the water or debris.
However, the reinstatement process does not cover the throat of the fitting (as depicted by the photo to the left). The orange portion of the pipe you see is a connection coming into a vertical pipe. The bottom portion, or where the water and debris will move from the lateral into the vertical pipe, is known as the throat, and is not covered or reinforced by the liner when using the Inversion method. During the reinstatement process, there is the potential to damage this fitting if the throat is already deteriorated or weakened. In this case, the fitting would then need to be traditionally removed and replaced.
The photo here shows a broken fitting, where the throat has failed and the inverted liner does not cover this portion, therefore making it necessary to traditionally repair by excavating through ground or wall to remove and replace the broken fitting.