AME Troubleshoots The Root Cause of Vibration and Pipe Resonance

A cargo ship was experiencing a recurring pipe failure on one of its chillers. AME was called out to troubleshoot the root cause of vibration and pipe resonance.

We arrived on site and performed resonance testing at multiple pipe locations to determine natural frequencies.

We collected vibration analysis and motion amplification data with the chiller operating at 20%, 50%, and 70% load, and we checked the runout of the motor and compressor shafts as well as the alignment.

We found the alignment well outside of allowable tolerances, so we performed a “hot” laser alignment between the motor and pump after the machinery reached its operating temperature.

Upon completing the alignment, we took post-vibration analysis data at 20%, 50%, and 70% load.

A vibration peak at the 4th order of rotating speed under 20% load conditions was exciting a natural frequency in the piping, and the best solution was to program the motor’s VFD to avoid that specific speed.