First rehabilitation of a pressure pipeline with Primus Line^® at home!

05 Apr 2023

Although on the market and in use worldwide for more than 20 years, the rehabilitation of a pressure pipeline took place for the first time in Holy Week and Easter week at the home base and headquarters of Rädlinger primus line GmbH: In Cham, a drinking water pipeline with a length of 260 metres was rehabilitated trenchlessly using the Primus Line^® system, extending the service life of the pipeline by at least 50 years.

The drinking water pipeline DN 200 to be rehabilitated made of cast iron and with an operating pressure of around five bar runs from the municipal utilities in Cham across the company grounds of a car dealership, crosses railway tracks as well as a busy street and ends on the open air swimming pool site.

Due to leaks, the municipal utilities had already taken a part of the more than 60 year old pipeline out of service. In order to be able to re-use it, a section with a total of 260 metres has now been rehabilitated with the trenchless Primus Line^® system. However, not much of the renovation was visible above ground: The Primus Line^® system was pulled in via just two construction pits at the beginning and the end of the section to be rehabilitated. The starting pit was located on the open air swimming pool site near the river Regen, the destination pit on the grounds of the municipal utilities.

For the civil engineering, Rädlinger primus line GmbH brought another local company aboard: Johann Wutz Hoch- und Tiefbau GmbH took care of excavating and securing the construction pits. In the starting pit in the open air swimming pool site, for example, the Wutz GmbH team had to install sheet pile walls due to the proximity to the Regen in order to prevent possible groundwater infiltration.

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How does the Primus Line^® technology work?

The Primus Line^® system is a technology for the trenchless rehabilitation of pipelines: It is not necessary to dig trenches, to remove the defective pipeline and to install a new one. Instead, Primus Line^® is pulled in into the existing pipes, ensuring continued use for more than 50 years. The Primus Line^® system consists of two components: on the one hand, the liner, a hose with a three-layer structure. The inner layer, either made of polyethylene (PE) or thermoplastic polyurethane (TPU), is suitable for most various media such as water, gas and oil. The outer layer of PE primarily serves to protect the liner during installation. The entire pressure of the pipeline – in this case an operating pressure of five bar – is absorbed by the middle layer. It is made of a seamless aramid fabric. The combination of these components makes the liner flexible and safe at the same time.

The second system component are the connectors by which the liner is connected to the existing distribution network. Rädlinger primus line GmbH not only develops connectors and liners, but also manufactures them in the district of Cham and installs them with its own installation teams in the DACH region. Internationally, the company works with a large number of specially trained partners.

Why trenchless technology?

In this project, Primus Line^® was able to show off several of its strengths. As this is a trenchless technology with only minimal civil engineering work, the rehabilitation of the drinking water pipeline went almost unnoticed. The duration of the renovation work was significantly shortened and the busy Badstraße did not have to be closed for this. Traffic could continue to flow at least on one lane, despite a structural change to an exit.
Primus Line^® crossed the car dealership grounds and the railway tracks underground in the old pipe just as it did in the sunbathing lawns on the open air swimming pool site – without additional, costly interventions, such as rerouting the rail traffic. This little impact on the environment predestines trenchless rehabilitation methods therefore for hardly accessible or protected areas.

Due to its flexibility, the liner is furthermore able to pass through bends. The rehabilitated section in Cham had five o fit with radiuses between 22° and 30°. As standard, Primus Line^® manages bends up to 45°, but even 90° under certain conditions.

In addition to this, Primus Line^® passed through shut down exits, like close to the car dealership. Separation of the pipes as with conventional open construction was not necessary.

The rehabilitation with Primus Line^® also optimised the pipeline’s flow capacity which previously had been impaired by heavy incrustations. Despite a small reduction in cross-section, the smooth inner layer of the liner provides the improvement.

How is trenchless technology installed?

A pre-inspection of the drinking water pipeline to be rehabilitated with a camera had revealed heavy incrustations in the pipeline due to corrosion. These incrustations were removed mechanically before liner insertion. The installation of the system itself was very simple: Another camera inspection determined whether the inner diameter of the pipe was free. Then the liner was pulled in into the host pipe. For this purpose, the liner was delivered coiled on a reel at the starting pit in the open air swimming pool site. A winch positioned at the destination pit on the municipal utilities’ grounds then pulled the liner through the host pipe. Insertion took place on Holy Thursday. The connectors were installed subsequently, the system then checked for tightness as well as hygiene and handed over to the customer. Recommissioning was taken over by the utilities’ experts staff.

There were two exits in the rehabilitated section, one to the service room of the open air swimming pool and one in the area of the Badstraße. There, the exit was set back towards the pavement so that the road does not have to be closed for future maintenance work.

The entire project was scheduled for a period of just under four weeks around Easter: digging the construction pits, cleaning the defective pipeline, pulling in the liner, installing the connectors and putting the pipeline back into operation. So that everything would be ready for the opening of the outdoor pool season.