Condition-based maintenance: A complete guide
Introduction to Condition-based maintenance (CBM)
CBM is an approach to the maintenance of machinery based on real-time condition data. It is a move away from traditional planned maintenance approaches that use pre-determined intervals to plan maintenance activities.
Reactive planned maintenance leads to too many failures resulting in periods of machinery downtime and increased running costs. DNV state: ‘Maintenance based on predetermined intervals or running hours will in many cases result in unnecessary maintenance and can lead to wear out or introduce failures caused by human error. This again results in reduced equipment reliability and increased downtime.’
The condition of machinery is derived from the collection of critical condition and performance data sets including but not limited to: vibration, speed, temperature, pressure, oil health and power. Through the monitoring and analysis of these combined data sets, issues can be identified early and the correct maintenance activities conducted at the right time. It is through this proactive approach that significant benefits can be achieved.
The benefits of CBM
The benefits of CBM include:
1. Prevent downtime due to failure - as early on-set of failures are recognized as part of the condition monitoring (CM) of machinery based on historical trending and pre-defined condition thresholds.
2. Reduce inspection time - as maintenance is only conducted when the condition of the machinery dictates.
3. Reduce maintenance costs - over the lifetime of the machinery both in terms of inventory and required labour hours.
The long-term trending of the condition and performance data sets for machinery also enables the implementation of predictive maintenance approaches. This enables the future prediction of issues based on previous running parameters.
Planned vs condition-based vs predictive maintenance
|Condition-based maintenance||Predictive maintenance|
Maintenance conducted based on pre-defined intervals (usually from OEM)
Maintenance conduced based on the condition of machinery at a point at which readings reach
Maintenance work scheduled at some point in the future based on long term analysis of data
Planned Maintenance System (PMS)
Services and solutions
Key considerations to deliver a CBM strategy
The below outlines some key considerations when embarking on a CBM strategy.
The identification of the machinery/asset to conduct CBM on is crucial. It would be operationally and cost ineffective to perform condition monitoring (CM) on every machinery on-board a ship or oil rig, so the initial selection of suitable machinery is critical. James Fisher advise machinery is selected based on:
a. Criticality - highly critical machinery where downtime can have significant impact
b. Failure rate - high failure rate of a particular machinery/asset type
c. High planned maintenance time/cost- planned maintenance is expensive both in terms of labour and inventory
d. High replacement cost - high cost to replace if catastrophic failure occurs
Condition monitoring (CM) parameters to be used
Once the asset/machinery is selected the next focus should be on the CM parameters to measure and drive your CMB strategy. CM data is usually broken down into:
a. Available performance data sets - usually acquired from the vessel automation system or manually. These parameters include: speed, load, power, pressure, temperature, running hours, position, sea state and distance.
b. Vibration data - vibration monitoring provides great insights into the health of machinery and is able to highlight issues such as misalignment, looseness and bearing degradation.
c. Fluid data - monitoring the contents of fluid such as lube oil can again provide important insights into the health and possible degradation of machinery.
Condition and performance monitoring technology & expertise
The selection of a suitable CM solution is crucial in being able to make sense out of the machinery data being combined and collected. James Fisher Mimic’s solution has been built on over 30 years CM experience. Find out more here.
4. Key integration points- even though significant value can be delivered through the implementation of a CM solution such as Mimic independently, greater benefit can be delivered through establishing key integration points
a. Planned maintenance systems (PMS)- integration to PMS- will ensure any issues identified can be linked into the PMS for action by the engineering team
b. Vessel automation systems- integration into vessel automation systems such as ABB or Valmarine enable the automatic integration of vessel performance data to drive condition insights based on the performance
5. Training and change management - CBM is a transition away from traditional PMS and so needs to be managed effectively. Change management will be required to ensure the organisation understands the benefits of doing so, and the overall improvements that will be delivered. This needs to be supported by effective training.
6. Establish core team and skill sets - To be able to effectively deliver all the points above, the establishment of a CM core team to drive the project forward will certainly ensure an effective journey.