Hydraulic method for closing steam turbine casings

One of the most time consuming operations during an outage of a power plant is the maintenance of the steam turbine. In many cases these operations are considered to be on the critical path and hence it is important not only to speed them up but also to make them as predictable as possible. For more than a decade now, hydraulic coupling-bolts have been used by all major turbine manufacturers and power producers in order to shorten outages and to avoid problems related to stuck bolts. Based on this experience and our knowledge in “oil-power” we have developed a system to hydraulically preload the bolts in a steam turbine casing. The authors describe the hydraulic preloading tensioning tool. The bolt, washer, nut and endcover, and the toolset are described