Cooling water pump gearbox diagnostics, failure and remedial actions

Haider Ali, Machinery Engineer, Engro Fertilizers (Int.)


Cooling water pumps are the life line of any petrochemical plant.

This case study expounds failure of gearbox installed on a cooling water pump with a rated capacity of 16240 m3/h at 47.5 meter of head. Bevel type gearbox is used to transfer work from horizontal stream turbine to vertical centrifugal pump. The unit was commissioned in 2010 and runs in parallel to 03 other identical pumps.

After 2.5 years of continuous operation. the unit developed an abnormal noise with slightly higher impacting (vibration waveform) on the gearbox. However upon inspection, increased back-lash (still in recommended limit) was observed on the unit and the machine was kept in operation.

During a startup in March 2014, high cyclic impacting was observed in vibration waveform which indicated gearbox wear/damage. Upon inspection leading edge teeth of the bevel gearbox was found broken.

The case study covers the complete RCA of GB failure and the remedial action taken on similar units installed on site.

1. Importance of single processing
2. Diagnostic of Bevel Type gear boxes
3. Checks during Commissioning of new unit


Haider Ali holds the chancellors silver medal in mechanical engineering degree and has a combined experience of 6 years in rotating machinery diagnostics in addition to maintenance/overhaul experience of turbo machinery (centrifugal compressors and steam turbines) and retrofits of gas-turbine components. He is widely recognized for his work on BCL compressors and tandem dry gas seals installation and troubleshooting. Haider joined Engro Fertilizer in 2013 and has since been the integral part of the diagnostics team for the World’s biggest single train Ammonia Urea complex. Haider is a VA-III Vibration analyst.