“Cured in Place Pipe (CIPP) lining is the insertion of a resin impregnated lining tube which is then cured to form a tight fit against the existing sewer”.

CIPP has been used to rehabilitate, aging wastewater pipes, since its development in the United Kingdom in 1971. It has been embraced by community infrastructure engineering groups around the world as offering an economical alternative to traditional open cut replacement techniques.

This non-disruptive, “trenchless technology” involves the inversion of a non-woven polyester felt tube, which is saturated with thermosetting resin and catalyst. The tube is installed in to the damaged pipe with either air pressure or water pressure. Once the liner has past through the existing conduit, between two access points the resin cocktail is heated using water or steam to form a tight fitting “pipe within a pipe”.

Pipe diameters from 75mm to 2500mm can be rehabilitated in less than one day, in most cases, Lengths in excess of 200m can generally be renovated within a 24 hour period.

Lateral service connections are re-opened either remotely, utilizing robotic cutting tools, or by hand, in larger diameter sewers. The intent, being to have all connections opened and back in service with a 12 hour period.

All CIPP liners should be designed in accordance with the ASTM-F1216 05 (please see Design Guide), which takes a number of existing pipe parameters into consideration in order to determine the liner thickness, which in turn governs the long term performance of the liner. The main parameters required for CIPP pipe design are as follows:

• Depth of Pipe to invert.
• Diameter of pipe.
• Shape of pipe.
• Ovality of existing pipe.
• Existing condition of pipe (Fully deteriorated or partially deteriorated).
• Level of ground water table above pipe.
• Modulus of surrounding soil.
• Density of surrounding soil.
• Live load conditions.
• Vacuum conditions.