In recent case studies, unexpected and unmonitored torsional vibration resulted in sudden failures, costly downtime and potential safety hazards. Part 1 of this article, which appeared in the January issue of Hydrocarbon Processing, examined the origins of torsional vibration and case histories to drive an understanding of the unmonitored risk existing at many industrial sites.
On December 15, 2002, an anomalous event occurred in a steam turbine of Unit 2 at the South Texas Project Electric Generating Station, a pressurized water reactor (PWR) nuclear reactor near Bay City, Texas. The ensuing investigation concluded that a blade was ejected from a low-pressure stage, and detailed inspections revealed additional cracked blades in several stages.