Turbine Vibration Field Study Case Study

Problem

A client had problems with excessive vibration of a recently reworked steam turbine. Because the turbine was not equipped with proximity displacement transducers, its shutdown eliminated electrical power to one of the facility's units.

Solution

KHE installed temporary displacement transducers and triaxial accelerometers at each bearing location. Using multi-channel field digital acquisition, KHE performed an orbit analysis of the shaft at the inboard turbine bearing and recorded data from accelerometers located on both turbine bearings. Based on this analysis, KHE diagnosed a rub internal to the machine as the most likely cause of the high vibration. Disassembly of the turbine confirmed that the shaft had been rubbing on the internal carbon rings due to a damaged turbine casing. The damage was most likely caused by excessive pipe loading which was corrected during a previous outage.

Result

The client made the necessary changes to the turbine to assure reliable operation, allowing the affected unit to resume normal operations