Industrial Case Histories: Who is to Blame?
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CASE HISTORY—PEER-REVIEWED
Industrial Case Histories: Who is to Blame? Kevin R. Guy
Published online: 19 March 2008 Ó Society for Machinery Failure Prevention Technology 2006
Abstract This paper is a series of case histories encountered over the past three years. While each case history is not necessarily outstanding in its own right, they do show the type of equipment problems encountered in today’s industrial environment. Many problems were manifested by the lack of forethought on the part of the management team and in other cases the forethought by management eliminated additional problems. The paper will cover cases that are fairly in-depth requiring rotor dynamic modeling, structural modeling or both. Each case has a lesson to be learned. This paper is an attempt to provide a resource of information with examples as a reference on specific problems with specific types of equipment. The goal of the paper is to help point the analyst in the right direction for developing an analysis plan and securing a solution to the problem. Each history includes a brief discussion on what equipment was utilized for the analysis. All cases presented in the paper show that planning during the analysis phase will lend itself to a successful resolution to the problem. In addition all cases show that a single piece of equipment (i.e. Data Collector) will not be adequate for the analysis. Keywords Misalignment Sub-harmonic resonance Imbalance Blade pass Whirl Whip
Based on the article of the same title published in Metrics: The Key to Success, Proceedings of the 60th Meeting of the Society for Machinery Failure Prevention Technology, Society for Machinery Failure Prevention Technology, 2006, pp. 201–255. Reprinted with permission. K. R. Guy (&) Delaware Analysis Services, Inc, P.O. Box 365, Francisco, IN 47649, USA e-mail: [email protected]
Structural resonance Variable frequency drives Bearing defect frequency Gear mesh Case #1: Unrepaired Turbine Alignment Issues Problem The concern was the difference in vibration amplitudes monitored in the control room from the low pressure bearing shaft rider versus the proximity (prox) probe reading collected with the plant data collector. The turbine is instrumented with General Electric (OEM) Shaft Riders on both the high pressure bearing (Inlet) and low pressure bearing (Outlet). Plant personnel have instrumented the low pressure turbine bearing with externally mounted prox probes to monitor shaft vibration. Five years previous, a vibration analysis was performed on this equipment. The problem at that time was an alignment issue between the turbine and pump. During the analysis, it was discovered that straight bore bearings were installed in the turbine. This turbine manufacturer calls for a minimum of an elliptical bearing in both the low pressure and high pressure end. Equipment Utilized for the Analysis CSI 2115 Data Collector, Teac Analog Tape Recorder— Four Channel, Prox Probes, Accelerometers, and MultiChannel Integrating Power Supply. Symptoms There wer
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