Reclamation Information Sharing Environment (RISE)

In 2009 a hydroelectric accident at the Sayano-Shushenskaya Powerplant in Russia killed 75 people and heavily damaged much of the powerplant. The accident was initiated when the headcover bolts on a generator turbine failed while in service. Every hydroelectric facility has critical bolted joint connects which if were to fail would have the potential to cause catastrophic consequences. Many of these connections are in inaccessible areas making inspection difficult. A problem with bolted joints is in keeping the threaded assemblies tight and knowing that the installed bolt has the required bolt load. Unequal and insufficient bolt loading is the primary reason for gasket joints to start leaking and bolts to vibrate loose and eventually fail through fatigue. During assembly, bolts can easily be over or underloaded leading to early failure. This research project evaluates the use and benefits of using modern sensor technology to monitor the tightness and health of selected threaded connections by using ‘smart’ washers and ‘smart’ bolts that can measure real-time bolt load. This sensor technology has the potential to easily measure the load on the threaded assembly without having to loosen and retorque the bolt, giving a direct indication of the health of the fastener. Reclamation studied selected sensors both in its laboratory and on turbine headcover fasteners on a large hydroelectric generator.