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Potable water line restored by Close Fit
Project name: Potable water pipe rehabilitation in the Close fit method in Lonsee Halzhausen
Project date: 2007 – 2012
Products: PE tube liner OD 1480 SDR 60, 2006 (540 m), 2007 (840 m), 2010 (1000 m), 2011 (850m)
„Bicycle tube should plug leaks“, was the headline of a daily newspaper in Baden-Württemberg. Three pipelines are annually transporting 90 million cubic meters of water to the north-east of Württemberg. Leaks on a 6.5 km long section were causing an annual loss of 500,000 cubic metres of water per year. Rising costs for potable water and increased resource problems meant a significant loss which had to be resolved.
Therefore Sublining was the chosen method of reconstruction. The prefabricated PE pipe was folded, then introduced into the existing concrete pipe and then loaded with an operating pressure of 8.5 bars. The inflation sets the tubes „close-fit“ to the existing concrete pipe. „Close-fit“ means that there is no gap between old and new installed pipe. Since this application with such a large diameter has not been installed before, various experts were consulted to evaluate the risk for execution.
First a test installation with 550 m was done. AGRU provided the so-called „bicycle-tube”, a PE 100 pipe with a special dimension of OD 1480 mm - SDR 60 and a length of 600 m. This prefabricated pipe was installed in spring 2007 and is operating since then with an operating pressure of 8.2 bars.
The costs for the rehabilitation of the leaking concrete pipe with 600 m were about € 500,000 and supplied a very cost effective and long-lasting solution for the customer. As alternative the new installation of a concrete pipe was estimated for the 600 m length with € 2.0 Mio. Because of the cost advantage and fast installation (the total relining of the prefabricated hose took less than 24 hours) and short down-time of the main water supply the authority has decided to reline also the remaining 6 km by means of that method. The renovation was completed in 2012. Since then further projects in other locations have been successfully installed with this proven method.
Project Status Quo
A time frame of 72h for the opening and closing of the gate valve of the OD 1480 mm pipeline is created by filling high-level tanks. Within this time the preassembled pipe (welded, squeezed off, cleansed, folded) has to be installed. Therefore there are always redundant systems to finish the drawing in within the time frame even though one unit might break down. The hydraulic pulling machinery could draw in the pipe with a load of ca. 40 t as planned.
The old pipe made of pre-stressed concrete was inspected by a calibration. Settlement and edges were removed by a sealer or concreted in order to avoid a jamming of the newly drawn in pipe.
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