Publications

Repetitive impellers failures have occurred in centrifugal compressor driven by gas turbine in 2010 � 2018 operated by Medco E&P Natuna Ltd. The first two forensic analyses have concluded that high cycle fatigue as the failure mechanism but what have caused the fatigue failure has not been defined and agreed. When the subsequent two failures happened, the team had been formed to conduct root cause analysis and consists of metallurgical team, rotordynamics team, Computational Fluid Dynamic (CFD) team, and stress analysis team to thoroughly analyze the failure specimens, measure the vibrations, conduct Frequency Response Function (FRF) test (ring/hammer test), and model all the forces acting on the impellers, including nodal analysis, to determine the impellers� level of stress. Extensive forensic analysis on the last failure event, including Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), discovered a similar failure mechanism but with more detail crack initiation and propagation. Laser 3D scanning was used to model compressor dimension for CFD and stress analysis modeling. Stress analysis uses the model to calculate the inertia, pressure, and steady state dynamic loads. FRF test result was used to compose interference diagram to check if interference is contributing to the failure. The analysis result is failure of the impellers have been initiated from the sharp corner of nose tip of impeller leading edge with the brazing joint acted as the weakest point. Tangential mode was also found during the vibration modeling and considered as the contributing factor to the failure.