Reliability Centred Maintenance
Reliability Centred Maintenance is the analysis and execution of Maintenance tasks focused on preventive replacements in order to maximise the operational period.
The focus on preventive maintenance is easily understood when consideration is given to the typical reactive type maintenance, ie “fix it when it breaks”.
In the typical reactive maintenance situation, the planned preventive maintenance gets delayed while resources are sidetracked performing emergency repairs to keep the system running after something has failed.
The delayed or cancelled preventive maintenance tasks then cause the system to be put at further risk due to it now operating beyond the planned / calculated maintenance periods. These operations beyond expected maintenance periods may place extra stress on the system, resulting in failure, diversion of maintenance resources to fix the failure, and a constant downward spiral in reliability. eg
- An oil change that is normally scheduled to be performed at 250 operating hours gets postponed due to a separate failure elsewhere in the system.
- The system is put back into service but the planned maintenance window for oil change has been missed and the system is now unable to be taken off-line for another 250 hours due to operational requirements.
- So now the equipment has to run on the same oil for 500 hours rather than the planned 250.
- If the original design did not allow for a maintenance period of twice the planned period, this may result in higher levels of contaminants and lower lubrication performance, and hence higher wear.
- This higher level of wear may show up quickly in terms of an earlier failure of an associated piece of equipment, or it may not show up for years, instead resulting in perhaps a major overhaul at 5 years instead of the planned 10 year expected life.
- Repeated maintenance delays may compound the unseen wear or degradation.
- Had the oil change been able to be performed at the same time as the initial failure, the costs involved as a result of the early overhaul, or equipment failure, could probably have been avoided.
It is the desire to avoid this type of downward spiral that drives Reliability Centred Maintenance, particularly for system critical functions. (Sometimes a failure in a piece of equipment is not critical to the operation of the system, so repair on failure is acceptable. eg a light bulb failure when there is sufficient light from surrounding light bulbs to allow operations in the area to continue.)