Troubleshooting a Pipeline Renewable Diesel Screw Pump

Elevated vibration levels were causing pipeline company screw pump problems.  Field tests were conducted to diagnose the cause and propose a solution to the problem of the pipeline pump.

• Problem Statement (Challenge)
  • What (type of machine): Pipeline Screw Pump
  • Where (State/ Country): Louisiana
  • Why (problem/reason): Determine the root cause of excessive piping, pump vibration, previous internal pump wear, and recommend solutions.
• Work Performed
  • Methods: Experimental Modal Analysis (EMA), Condition Monitoring, and Operating Deflection Shape (ODS)
• Results/ Solution
  • Findings: Piping natural frequencies shift into strong resonance at times. Pump twist modes go into resonance due to a lack of stiffness in the baseplate, driven by piping motion.
  • Impact: Piping structural supports were recommended to increase the separation margin from excitation sources.  Grouting the baseplate was recommended to increase system damping and to shift the natural frequencies away from the running speed excitation.

FFT plot from an accelerometer located on the discharge pipe.

Operating Deflection Shape at 17.3 Hz