Pharma Plant HVAC Fan Bearing Lubrication Contamination

This case study is from a generics pharmaceutical manufacturing plant located in Ireland, Europe. The Eastway Safeguard® online monitoring system was installed in 2015 on the critical Heating Ventilation Air Condition (HVAC) during the installation phase of a new expansion of the manufacturing plant. All critical HVAC were fitted with vibration sensors and connected to the Eastway Safeguard® prior to the commissioning of the plant extension.

The Eastway team support the on-site maintenance personnel in this plant both on-site and remotely. Prior to the Safeguard® system installation, Eastway were already working in the original plant, providing bi-monthly vibration analysis surveys and bi-annual thermography inspections. This on-site work has continued in conjunction with the 24/7 monitoring of the critical HVAC in the expansion.

Case Description

In May 2020, following annual maintenance works, the AHU’s across the expansion plant were re-started and automatic alerts were sent to key personnel and the Eastway team from the Eastway Safeguard® system monitoring AHU17. This HVAC unit has one supply motor, a pulley belt driving a fan shaft and impellar. There are 4 vibration sensors fitted across the motor and fan.

It was noted that the vibration was higher than expected from the Fan Drive Bearing and Fan Non-Drive Bearings on this AHU. See Figure 1 for Fan Drive Bearing Acceleration (g RMS) Trend and Figure 2 for Fan Non-Drive Bearing Acceleration (g RMS) Trend.

Machine Name AHU17 Supply Fan
Description Belt Driven Motor Fan
kW 11
Motor Plate RPM 2900
Bearing – NDE 6207-ZZ
Bearing -DE 6308-ZZ

Figure 1 Fan Drive Bearing Acceleration Trend 19 March 2020 to 10 May 2020

Figure 2 Fan Non-Drive Bearing Acceleration Trend 19 March 2020 to 10 May 2020

Immediate further investigation was completed by Eastway,an example of this analysis was the interpretation of the vibration Fast Fourier Transform (FFT), demodulation enveloped spectra and time waveform signature. This analysis concluded early evidence of a Fan Bearing impacting potentially caused by low or contaminated lubrication. See Figure 3 for Fan DE FFT spectra, Figure 4 for Fan DE Time Waveform and Figure 5 for Fan DE Demodulation Enveloped Spectrum all from 09 May 2020.

Figure 3  Fan DE FFT 09 May 2020

Figure 4 Fan DE Time Waveform 09 May 2020

Figure 5 Fan DE Enveloped Spectrum 09 May 2020

Based on this analysis, it was recommended to plant maintenance personnel to initially lubricate the Fan Bearings to reduce this vibration.

This lubrication was completed within 1 day on 11 May 2020 and the vibration initially reduced.

However, the vibration increased again within 5 days and on 16 May 2020, warning vibration alarm levels were breached and on 17 May 2020 the higher-level limits were again triggered. See Figure 6 for this confirmation of this temporary reduction and then increase again in trend.

Figure 6 Fan NDE Acceleration Trend 19 March 2020 to 22 May 2020

Recommendation:

Following the second increase, it was recommended by Eastway to further investigate the lubrication of the Fan bearings. It was recommended to clean out the existing lubrication and re-lubricate with fresh grease in case lubrication contamination had occurred during the shutdown period.

Action Taken:

This was completed on 22 May 2020 by plant maintenance personnel. Eastway supported the works by closely monitoring the vibration levels once the AHU restarted.

Following this maintenance work, the vibration trends reduced and have remained satisfactory since these works were completed with no further works required, see Figures 7 and 8. The previous evidence of vibration impacting within the Fan Bearings also reduced significantly in the vibration signal, see Figure 9 for an Acceleration FFT Waterfall comparison from 09 May 2020 and 24 May 2020 (post maintenance).

Figure 7 Fan Drive Bearing Acceleration Trend Feb 2020 to Oct 2020

Figure 8 Fan Non-Drive Bearing Acceleration Trend Feb 2020 to Oct 2020

Figure 9 Fan DE Acceleration (g RMS) Waterfall Comparison of FFT’s from 09 May 2020 (Rear) and 24 May 2020 (Front)

Results: Estimated* cost savings associated with avoidance of unplanned downtime, emergency repair costs & secondary damage:

Downtime avoided: 6 hours
Downtime cost per hour €20,000
Total Savings: €120,000