Reliability Centered Maintenance is identified as one of the most powerful tools a company can use to get more value from its physical assets.
It is the foundation of highly successful maintenance programs to ensure that machines help operations to deliver the results as required, yielding or exceeding the anticipated financial outcome required by the participated departments.
Definition of Reliability
“The ability of the system to execute its required function within specified working conditions over a stated period of time”
It is a means to improve reliability and maintainability performance to achieve greater uptime.
The RCM process requires a team, that is comprising different departments to study and answer the below few questions about the asset being assessed:
Repairing actions after failure.
Preventive maintenance (PM)
In preventive maintenance, restorative steps are taken prior to failure, also known as time-directed planned maintenance.
Monitoring steps that are predictive of failure, also known as predictive testing and inspection (PT&I) or condition-based maintenance (CBM).
Includes root-cause failure analysis (RCFA),age exploration, Expansion of failure mode and effects analysis (FMEA) absorbs this knowledge into the new design to continually improve performance and extend equipment life.
REACTIVE MAINTENANCE STRATEGY
A reactive maintenance strategy is performed when equipment performance is unsatisfactory.
- No downtime between failures
- Traditionally accepted by maintenance personnel
- Easy to justify to outside groups
- large spare parts inventory
- Quick response required from trained personnel
- Unscheduled work outages
- Longer restoration time
- Higher restoration costs
- Low manageability of budget, personnel, and parts
- Disregard of safety
- Possible collateral damage
A negative aspect of reactive maintenance is that failures frequently occur unexpectedly, severely disrupting operations.
Emergency repairs can be expensive;
Labor, spare parts and supplies may not be immediately available;
Costs for normalizing the equipment back to service may be high, and
The operational effect can be far more serious than the mere cost to repair the system.
PREVENTIVE MAINTENANCE STRATEGY
A preventive maintenance (PM) strategy consists of restorative-type maintenance actions planned to improve equipment condition and prevent or delay failure.
PM is successful in
- Reducing the risk of catastrophic failures
- Extending the interval between failures
- Maintaining equipment at high-performance levels
Overcoming some of the disadvantages of a reactive strategy
The largest disadvantage of preventive maintenance (PM) is that improper execution of maintenance tasks often creates more problems than if the maintenance had never been performed.
So many problems may remain, immediately after returning equipment into service following maintenance.
- Risk of catastrophic failure can be avoided
- Prevents equipment failure
- Overcomes some disadvantages of reactive maintenance
- Operating time per cycle is reduced.
- Costly unneeded maintenance is performed.
- Operational restrictions result in deferred maintenance.
- Frequency intervals are planned on limited data and vendor recommendations
One negative feature of PM is that the equipment availability is reduced by intentionally taking equipment offline in order to perform many of the PM actions.
Note: PM execution requires very good coordination among operation and maintenance departments.
PROACTIVE MAINTENANCE STRATEGY
Reliability-centered maintenance seeks the best mix of
- Preventive maintenance-based actions, and
- Corrective maintenance actions to form an in-depth program.
- Predictive test and inspection actions.
The system used in RCM to determine this optimum blend of maintenance actions is based on employing these additional proactive maintenance techniques:
- Failure mode and effects analysis (FMEA)
- Root-cause failure analysis (RCFA)
- Age exploration
- Precision rebuild and installation, verified with certification
- Failed part analysis
- Reliability engineering
- Recurrence control
These approaches improve maintenance through better design, installation, maintenance procedures, workmanship, and scheduling.
The characteristics of proactive maintenance are
- Use feedback and communications to make sure that changes in design or procedures are rapidly made available to designers and managers.
- Employ a life-cycle view of maintenance and support functions.
- Employ a continuous process of improvement.
- Amend and mould maintenance techniques and technologies to each application.
- Merge all functions that support maintenance into maintenance program planning.
- Use root-cause failure analysis and predictive analysis to enlarge maintenance effectiveness.
- Adopt an ultimate goal of repairing the equipment forever.
- Periodically check-out the technical content and performance interval of maintenance tasks (PM and PT&I).
A proactive maintenance program is on top of the RCM philosophy.
Failure mode and effects analysis provide an evaluation of each function of the system or equipment that may lead to a functional failure.
Functional failures are the many ways in which the functional requirements will not be met.
Each functional failure is categorized into dominant failure modes, which are observations as to why and how functions will not be met.
Each dominant failure mode is then analyzed to find out specific reasons, or failure causes, that will lead to an occurrence of the dominant failure mode.
Advantages of Reliability Centered Maintence
- Equipment availability will be Improved.
- Maintenance costs will come down
- Resource costs or expenses come down.
Author: PSS Bapu Rao