During a recent inspection conducted at a Hunter Valley based Coal Handling and Preparation Plant, our technician identified a drive pulley that was registering an elevated reading, indicating higher than normal vibration levels from the component.

The reject conveyors at this particular site had their pulleys greased regularly, and were being monitored for degradation, as the bearing housing had been impacted by debris. After receiving an elevated reading of 18.0Hz peak with harmonics in the velocity system, the pulled was impacting to a maximum of 2.1G’s peak to peak in acceleration. Following the recommendations of our technician, the component was initially flagged as investigate and monitor.

Over a four-month period, our technicians proceeded to assess and monitor the defect, and the pulley was greased each survey. The defect had then jumped in reading from 0.3G’s p-pk, to 1.6G’s pk-pk, which informed the recommendation from the attending NES Technician to replace the pulley. The component remained in place, however was closely monitored, and the change-out occurred in the following months.

The pulley was replaced without incident, the acceleration levels reduced and indications in the adjacent lower bend pulley were resolved also.

The effective monitoring and preventative maintenance actions taken by NES potentially prevented breakdown time in excess of 24 hours.