HOBAS Pressure Pipes Ensure Filisur Power Plant Operation for more than 50 years

The first GRP pipes by the dye works “Basler Stückfärberei AG”, from which the company HOBAS evolved, were produced in Basel, Switzerland, in the 1950s. The founding fathers already suspected that their product was something very special. One of the first clients that utilized HOBAS Pipes as penstock for a hydropower plant was the Swiss power company Albula Landwasser Kraftwerke AG.

The corporation was founded in 1961 and today runs hydropower plants in numerous valleys in the canton Grisons, in the east of the country. One of these is the power plant Filisur where, in 1965, 480 meters GRP pressure pipes 1250 mm in diameter were installed as penstock. Making use of the natural incline, water from Tuor creek 1423 m above sea level is first conveyed through a sand trap and then transported through a GRP pipe to the hydropower gallery Bergün/Filisur. Turbines subsequently transform the generated water power into electric energy.

The first 245-meter-long section of the pipeline was installed in open trench along a road with 2.4 meters cover. On the second section of 235 meters the pipes were encased with 20 cm of reinforced concrete and installed beneath the road. Basler Stückfärberei conducted all assembly works themselves. A challenge in this project was the difficult accessibility of the terrain. Bends were utilized to optimally adapt the pipeline route to the terrain. Thanks to the comparatively light weight of GRP, the pipes could be transported with ordinary cross-country vehicles and without special equipment. Construction works progressed quickly and were finalized within the months May to July despite strongly varying temperatures between 5 and 30° C.

Today, more than half a century later, the hydropower plant Filisur is still in operation. Together with the plant Tiefencastel it produces around 381 million kWh which approximates 5 % of the annually produced electricity in Grisons. Over the years, the GRP pipes have been regularly inspected and have been reliably doing their job ever since the plant’s startup.