Coupling Fault

Coupling fault detected by Vibration Analysis inspection of a jacket cooling pump

Coupling Fault Detected in Jacket Cooling Pump

Jacket cooling pumpInspection description: Vibration analysis inspection of Jacket Cooling Pump

Frequency of inspection: Monthly

Equipment description: Motor – Coupling – Pump running 24/7

Vibration reading (Velocity Power Spectrum o/all value 2.084mm/s) from the Motor Drive test point recorded in March 2012:

Vibration reading (Velocity Power Spectrum o/all value 2.084mm/s) from the Motor Drive test point recorded in March 2012:

This spectrum indicates the vibration peaks at running speed (1X) and multiples of running speed (2X, 3X, 4X and so on). The o/all levels recorded are low however the pattern would indicate an emerging coupling fault.

Vibration reading (Velocity Power Spectrum o/all value 11.47mm/s) from the Motor Drive test point recorded in June 2012:

Vibration reading (Velocity Power Spectrum o/all value 11.47mm/s) from the Motor Drive test point recorded in June 2012:

This spectrum indicates an increase of c. 700% in the 2X vibration component at the Motor Drive test point, indicating severe shaft – coupling misalignment.

Fault detection and action

Fault detected: Severe misalignment of motor – pump coupling. Possible damage to coupling

Recommended Action: Investigate coupling condition. Align motor - pump

Action Completed: Coupling inspected and found to be severely damaged. Coupling replaced.

Vibration reading comparison (Velocity Power Spectrum) from the Motor Drive test point recorded in July 2012 pre-replacement (middle and bottom readings) and in Nov 2012 (top reading) post-replacement.

Vibration reading comparison (Velocity Power Spectrum) from the Motor Drive test point recorded in July 2012 pre-replacement (middle and bottom readings) and in Nov 2012 (top reading) post-replacement.

This spectrum indicates that the previously highlighted 2X vibration component has reduced by c. 60% after the coupling was replaced. However the motor – coupling -pump was not precision laser aligned following the replacement.

Vibration reading (Velocity Power Spectrum o/all value 2.389mm/s) from the Motor Drive test point recorded in Jan 2014:

Vibration reading (Velocity Power Spectrum o/all value 2.389mm/s) from the Motor Drive test point recorded in Jan 2014:

This spectrum indicates that following precision laser alignment of the motor-coupling-pump, the 2X vibration component has reduced by a further c. 50% from the original baseline.

Summary of vibration trend (Velocity Power Spectrum) from the Motor Drive test point from Oct 2010 to Jan 2014.

Summary of vibration trend (Velocity Power Spectrum) from the Motor Drive test point from Oct 2010 to Jan 2014.