Pumped storage plant in the Glarus Alpine valley
A typical application for STAUFF Form EVO, under extreme operating conditions our forming system is the safest connection method
“Driving on snow, rolling on trails, swimming in a mountain lake, climbing rock faces” – that is how the Glarnerland region, about 100 km from Zurich, presents itself as a region for active holidays at any time of the year. “Even when rainy days turn the Glarner Alpine valley a dull shade of grey, there is still plenty to see and experience.” Guided tours of the Limmern pumped storage plant at an altitude of about 1700 m in the Swiss Alps are an unusual tourist attraction.
In the latest expansion stage, the Muttsee lake 630 m higher up was integrated in the power generation solution. With a length of one kilometre, its retaining structure is the longest in Switzerland. It holds 23 million cubic metres of water that can be drained to generate electricity. At full capacity, four turbines generate a total power of 1000 MW.
A look into the machine cavern that was built completely inside the mountain impresses not only laypersons: It is 150 m long, 30 m wide and 53 m high.
Werner Thorwarth, sales representative for STAUFF Connect at STAUFF Germany, is overwhelmed every single time: “The access to the machine cavern is already an adventure: You have to come up from the valley with the cableway through a four kilometre long gallery.”
During the construction phase, this was used for transporting around 1.4 million passengers, while 3.5 million tons of materials were moved up and down with this unit and two other specially installed cableways. 250,000 cubic metres of concrete were used in the construction of the barrage dam alone.
Powerful and Safe with STAUFF Form EVO
The capacity of a power plant such as this one depends on many factors. One is the safety of the hydraulic line systems, where strong vibrations place great strain on the connections.
A typical application for STAUFF Form EVO, as Werner Thorwarth explains: “Our forming system is the safest connecting method under extreme operating conditions.”
When the power plant was built and commissioned section by section in 2016/17, however, cutting ring fittings (from a different manufacturer) were used. Only two years later, the first leaks were detected during maintenance work. The damage analysis by the Swiss partner Fluidtec showed that cracks had appeared in some cutting ring connections. This is when the colleagues from Werdohl came in to present STAUFF Form EVO and the associated forming machine at the customer site.
The STAUFF Form tube forming system was first presented in 2015. Since the beginning it has undoubtedly been one of the most efficient solutions available on the market for connecting metric tubes. In addition to its simplicity, it convinces with a high degree of safety, reliability and reproducibility.
With STAUFF Form EVO, STAUFF now presents the latest generation of the tube forming system, which is characterised by an increased level of efficiency and versatility as a result of continuous optimisation.
STAUFF Form EVO has been designed as standard for seamless cold-drawn precision steel tubes as well as stainless steel tubes with dimensions between 6 x 1.5 mm and 42 x 4 mm in the Light Series and between 6 x 1.5 mm and 38 x 6 mm in the Heavy Series.
If required, parameters for alternative materials are available upon request and can be added by the manufacturer or via the optional cloud connection module integrated in the machines.
Werner Thorwarth and his team were soon able to convince Oswald Hauser, head of the Mechanical Systems division at Kraftwerke Linth-Limmern AG, of the benefits of STAUFF Form EVO. The owner of the power plant invested in the forming machine. Since then, the stainless steel cutting ring fittings have gradually been replaced with formed connections.
STAUFF employees from Werdohl in Germany visited the site multiple times to give the maintenance team a detailed induction into the machine and, later on, to exchange experiences and support the installation of the first updates.
Oswald Hauser: “Changing to STAUFF Form EVO is an important technical step for us and a also benefit with regard to work processes, reliable assembly and maintenance effort.” After all, there are dozens of kilometres of stainless steel tubes at the Limmern pumped storage plant and around 18,000 litres of oil that absolutely must not leak into the plant or into the environment.
Werner Thorwarth: “STAUFF Form EVO is a maintenance-free, permanently sealed connection system.” When replacing the first cutting ring fittings, the installers were already able to experience how easy the installation is: “The installation path after reaching the fixed point is clearly defined, which means that a tightening torque can be used. Due to the short rotation path of approx. 15° to 20°, the system can be installed even in tight spaces and highly adverse conditions.”
Of course the pumped storage plant also uses the cloud connection for transmitting updates online. The machine history and parameters, for example, can be viewed through an online service and analysed together with the account manager.
This simple quality assurance solution reduces engineer visits to the customer significantly, although Werner Thorwarth would prefer to travel to the Glarner region more often: “The first time we went there it was foggy and rainy. During the tour, we could only imagine the gigantic size of the barrage dam. The whole experience, with a view of both lakes and the snow in the Alps, was just overwhelming.”
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