Background
After only a few months following commissioning in 2002, the Hamilton City Council Pukete waste water treatment plant aeration blowers suffered a number of motor bearing failures. With the motors being repaired at ABB's Hamilton Service Centre, ABB assisted the Council to determine the root cause of the failures and appropriate corrective actions. Following that success, ABB was then engaged to provide planned maintenance on the blowers to ensure their ongoing reliability.
The maintenance programme included:
- stringent lubrication program
- oil analysis (quarterly)
- vibration analysis (monthly)
- oil replacement on condition
- annual flushing
- remove frame resonance
Maintenance cost savings
In the nine years this program has run, there have been no motor bearing replacements and no major mechanical failures. At an early stage in this blower maintenance schedule, modifications were made to the blower unit frames to reduce resonant vibration. This improvement in reliability has allowed the Council to extend major service intervals by 50% and save $30,000 in annual maintenance costs.
Reduction in machine faults
On the back of this successful blower maintenance program, Hamilton City Council has pursued a wider vibration analysis programme throughout their water supply and waste water infrastructure.
The objectives of this programme were to:
- improve confidence in plant availability
- focus maintenance spend
- identify improvement opportunities
- extend plant life
- reduce the need for expensive system redundancy
This plan currently includes routine vibration analysis of 128 machines. Additionally, the Council has pursued further reliability initiatives supported by ABB which include root cause failure analysis, precision machine alignment and balancing of rotating assemblies.
The information collected has lead to a 50% reduction in machine faults, and an improvement in plant condition. Consequently, a thorough understanding of fault conditions has improved availability by focusing corrective maintenance activities on priority equipment.
Sven Ericksen, Asset Maintenance Team Leader, from Hamilton City Council comments that the programme has resulted in an overall increase in plant availability and confidence in plant condition:
"While the vibration monitoring has brought benefits by increasing the work carried out under planned shutdown conditions (51%), a key indirect benefit has been when early failure is identified within our environmental protection systems. This has allowed Hamilton City Council to keep regulatory authorities fully informed of upcoming maintenance work on these assets and providing them with impact mitigation plans for the work."
