Case Study: Why Case Monitoring of Large Turbo-Machinery Adds Value

Jeffrey Mauk, Equipment Monitoring Technician, BP Products North America


My presentation will describe the events with plots and information that detail the failure of the unit. The K1 Turbine Driven compressor was overhauled in 10-16.  In January of 17 the machine had run for only a few months, when the vibration increased slightly on the mils reading from the supervisory system and analysis software.  At first there was little indication of a larger problem.  Then will conducting the quarterly case monitoring a significant step was apparent.  Once the increase was notice the Vibration Technician (me) responsible for the monitoring of the K1 compressor began diagnosing the change.  The 1X amplitude at proximity probes increased with indication of a 90 degree phase shift.  Vibe levels were below minimum amplitude, so a more complete analysis was needed.  A real-time analyzer was used measure the case vibration.  The keyphasor signal was brought into the analyzer, for direct comparison to the proximity probes.  This would correlate with the supervisory system software.  Once I examined the waveforms and the phase shift I was confident we had loss blades or something had shifted in the rotor.
I made my analysis known to our engineers and they wanted our expert to review my findings.  He disagreed with my assessment because the vibration probes low barely over two mils.  He concluded that a rub was causing the vibration, based upon this machine having a similar incident when it was test run at a vendor facility.  I offered more than once to provide him with the case data and he didn’t want it.  I didn’t see anything in the orbits that indicated rub.
The turbine was pulled and upon opening the case it was discovered we had loss blades on 1St and 2nd stage.


1.) Always be courageous
2.) Believe your instruments (starting with the transducer)
3.) Use all the tools available to you.


Journeyman Maintenance Machinist with 35 years in heavy industrial maintenance, machining, equipment installation and repair. 22 years of vibration analysis and equipment monitoring. Level 3 vibration analyst.