An detailed integrity assessment of a 25 MW hydro-electric power station penstock

The present paper describes a detailed integrity assessment of a riveted penstock in a hydro-electric station which supplies around 25 MW to the grid. It was found that the remnant life for (a) a collection of imposed severe operating conditions, (b) maximum corrosion damage conditions and (c) a stringent probability of failure value, Pf, of 10−4 was estimated at 75 years. It was also shown that the possibility of a fast fracture event in this particular penstock was remote.Finally, a further future programme of NDT work, aimed at validating the present integrity assessment, was proposed to be carried out within the next 5–6 years. This NDT work aimed to inspect around 15% of all the rivets located in this penstock.