Torsional Vibration

Paper No. 86

By Troy Feese and Charles Hill
Presented at the GMC Gas Machinery Conference
Nashville, TN, October 2002.

There are numerous books and technical papers on the subject of torsional vibration, so the phenomenon should be well understood and easily controlled. However, numerous torsional vibration problems continue to occur in reciprocating and rotating machinery. One reason for this is the mating of equipment traditionally used in non-reciprocating applications (such as variable speed motors) with reciprocating compressors. Other reasons may include lack of monitoring engine or compressor performance, as well as improper application and maintenance of viscous dampers and elastomeric couplings. The purpose of this short course is to raise awareness of torsional vibration problems that can occur in reciprocating equipment, and to give guidelines based on experience with actual systems to avoid these problems in the future. A list of recommended items that should be considered in the initial design stage, analysis stage, and after the system is in service is provided to help attain maximum reliability. The need for torsional vibration measurements during commissioning to verify acceptability of critical applications is also discussed.

Ten different case histories are presented where failures were linked to torsional vibration. In general, the solutions to these problems were based on practical considerations that could be retrofitted in the field. Of particular interest are the failures that could not have been predicted if only an “ideal” operating condition was analyzed. The results of these investigations emphasize the need for more comprehensive torsional analyses in the design stage of critical systems. Advanced software for performing steady-state and time-transient torsional analyses should have the following capabilities:

 

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