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Close-fit Lining

This category of renovation covers pipe lining systems that install a new pipe lining within the existing pipe in a manner that provides a tight or reasonably tight fit to the inner surface of the existing pipe. This is important in maintaining the maximum remaining pipe cross-section after the renovation and also in allowing the new lining an ability to interact structurally with the existing pipe. For reduction of infiltration into gravity sewers, a tight fit for the new lining also reduces the possibility for infiltration to track along the annular gap between the lining and the host pipe. A variety of approaches may be used to accomplish this as categorized in the sub-methods. Conventional slip lining typically is not considered a close-fit lining (even if grouted) since sufficient clearance must be allowed between the new pipe and the host pipe for its installation and hence the diameter reduction is greater than for a close-fit lining. However, when structural grout is used to form part of a liner system, the technique can be considered to create a “close-fit” liner even if the interior portion of the liner has a significantly smaller diameter.

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