Abstract
A hydropower station, which has been in operation for over 50 years, has a penstock located in the plant’s open pipe section. Recently, concerns have been raised regarding the potential risks to the penstock’s safe operation due to wall thinning caused by abrasion. A series of stress tests, strength mathematical model analysis, and sediment erosion tests were performed on the penstock during turbine load rejection events. A stress and strain monitoring system for the steel pressure pipe was developed, enabling real-time monitoring and providing a warning function. The current wall thickness of the steel pressure pipe is about 28 mm. The results indicate that a pipe rupture is unlikely under any load rejection scenario. However, if the wall thickness is reduced to around 24 mm, the maximum equivalent stress of the pipe will approach the safety limit during load rejection. The sediment erosion test showed an erosion rate of 3.509 × 10–5 mm/h at an average sediment concentration of 0.63 kg/m3. Assuming no other factors, such as an increase in river sediment concentration, and based on the design specifications of the steel pressure pipe and the annual average sediment concentration of 0.63 kg/m3, it is projected that the open pipe section can be operated for about 19 years before the wall thickness reaches 24 mm. It is recommended that once the wall thickness reaches 24 mm due to erosion or other factors, the pipeline system undergoes maintenance or replacement. The findings provide significant guidance for the operation of similar power stations.
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