Dynamic effects of electrical pitting in steam-turbine tilting-pad thrust-bearings

Pennacchi, P., Ricci, R., Chatterton, S., Borghesani, P., Vania, A., D'Antona, G., Pensieri, C., & Rolla, C. (2012) Dynamic effects of electrical pitting in steam-turbine tilting-pad thrust-bearings. In Proceedings of the ASME Design Engineering Technical Conference, ASME, Chicago, Illinois, USA, pp. 731-738.

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Abstract

This paper merges the analysis of a case history and the simplified theoretical model related to a rather singular phenomenon that may happen in rotating machinery. Starting from the first, a small industrial steam turbine experienced a very strange behavior during megawatt load. When the unit was approaching the maximum allowed power, the temperature of the babbitt metal of the pads of the thrust bearing showed constant increase with an unrecoverable drift. Bearing inspection showed that pad trailing edge had the typical aspect of electrical pitting. This kind of damage was not reparable and bearing pads had to replaced. This problem occurred several times in sequence and was solved only by adding further ground brushes to the shaft-line. Failure analysis indicated electrodischarge machining as the root fault. A specific model, able to take into consideration the effect of electrical pitting and loading capacity decreasing as a consequence of the damage of the babbitt metal, is proposed in the paper and shows that the phenomenon causes the irretrievable failure of the thrust bearing.

Impact and interest:

2 citations in Scopus
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ID Code: 66494
Item Type: Conference Paper
Refereed: No
Additional Information: ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference.
Volume 1: 24th Conference on Mechanical Vibration and Noise, Parts A and B
Additional URLs:
Keywords: Electric discharge, electrical pitting, Thrust bearings, steam turbine, tilting pad
DOI: 10.1115/DETC2012-71132
ISBN: 9780791845004
Subjects: Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > MECHANICAL ENGINEERING (091300) > Numerical Modelling and Mechanical Characterisation (091307)
Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > MECHANICAL ENGINEERING (091300) > Tribology (091309)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2012 by ASME
Deposited On: 22 Jan 2014 00:08
Last Modified: 01 Apr 2014 23:05

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