Lake pressure pipelines for wastewater were built in several lakes in Austria since the beginning of the 1970s. This also applies to the Fuschlsee in...Read more
PE 100 pipes for rehabilitation of damaged pipes
Project Date: 2014
Product: PE 100 AGRU SureFIT Liner OD 250 mm, SDR 26
Medium: sewage water
The municipality of Abtenau decided to rehabilitate all pipelines in the residential area due to the incrustation and leakage of the pipelines. The incrustation was caused by hard water. Since the town centre couldn’t be blocked for the construction site, it was decided to use a trenchless installation method for the rehabilitation.
The project was opened for public tendering and the installation was carried out by the company SPR Austria GmbH. The AGRU SureFIT liner from AGRU was used for the rehabilitation. If proper equipment is available, the installation is fast and safe.
The AGRU SureFIT liner is produced as a round pipe, and folded while still warm into a U-shape. The results are that a cross-sectional reduction of approximately 30% is reached. This makes it possible to move it into the existing host pipe. After the insertion process, the liner gets heated and deforms back to its original round shape.
Setup of the construction site
The pre-folded liner is delivered on a coil and is positioned in front of the access shaft.
The old pipe made of asbestos cement is first milled and cleaned by a milling robot.
Then the pipe is inspected by a camera. During this inspection steel rope gets inserted, which is used for pulling the liner through the existing line.
The liner gets inserted by a winch.
The insertion procedure is done uniformly until the pipe end protrudes far enough into the other manhole in order to mount the connectors.
Preparing the connections
The liner is separated from the reel using a chainsaw and brought into position for re-rounding.
A hot air or a flame unit heats up the pipe ends until the material is softened. Then, special caps are applied to the pipe ends. These are available for each dimension. The end caps are fastened with special chains, which are mechanically clamped to the pipe to ensure that no leakage occurs during the steaming process.
Then the steam generator is connected to the cap at the beginning of the pipe with a hosepipe.
The pipe end is connected to a chimney in order to control the flow of the steam.
Additionally, external temperature sensors are mounted to measure the material temperature at the beginning and at the end of the pipeline.
Heating with pressure and steam
The entire piping is exposed to hot steam (about 120 °C) and pressure (about 1 bar).
The temperature can be controlled by regulating the steam flow with a valve mounted on the chimney.
After reaching 80°C at the outer surface of the liner, the so-called „memory effect“ sets in, which causes the pipe to take its original shape. This creates a new round tube without annular gap to the old pipe.
The cross-sectional reduction is often compensated due to the smooth pipe surface and the thereby resulting very good flow properties.
The entire process duration is about 24 h, depending on the size and length of the pipe.
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