Rehabilitation of a DN 150 drinking water pipeline using the PEHD Close-Fit Liner method
In spring 2020, specialists from Esders Pipeline Service GmbH rehabilitated a 680 m long drinking water pipeline in the idyllic landscape of Franconian Switzerland. After several pipe bursts, the client decided to use the PEHD inliner pipe using the close-fit method for cost-effective and sustainable rehabilitation. Maximum pipe cross section after rehabilitation and minimum civil engineering effort are the outstanding features of this method. Due to the presence of strata water in the mountainous hillside location, dewatering was a particular challenge in this construction project.
Close-Fit Lining is suitable for the rehabilitation of water, sewage pressure, industrial, gas and sewer pipes made of all common materials. The nominal diameter range extends from DN 100 to DN 500.
The close-fit lining pipe is a factory extruded, pre-formed HDPE pipe wound on reels. Due to the controlled deformation process, the cross-section is reduced by approx. 35% and the bending radius of the pipe is reduced. This allows the PEHD pipe to be pulled into the pipeline to be rehabilitated without much effort via small excavation pits or through manholes. Process-controlled pressure and heat application ensure that the PE pipe lies “close-fit” to the inner wall of the old pipe due to the so-called memory effect.
The quality and service life of the new PE pipe are comparable to a new installation. The result is a statically independent and resilient pipe that effortlessly meets even strict economic criteria. In addition to the short installation time, other advantages include the fact that, in contrast to open pipe construction, excavation work is usually only minimal, or even completely unnecessary in the sewage sector, as the manholes can be used as working space. Up to 600 m of pipe in the DN 100 nominal diameter range and up to 100 m in length in the DN 500 nominal diameter range can be rehabilitated in a single operation.