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Corrective Maintenance
A form of maintenance whereby no routine maintenance tasks are performed. The only “planned” maintenance on the asset is restoration after a problem necessitates some action.



Attributes
Listed below are some of the variations on corrective maintenance:
Listed below are some of the key attributes of a corrective maintenance program:
  • To restore an asset after failure has occurred
  • In some cases, a conscious decision is made to neglect an asset until it fails or until some type of problem emerges. Where this occurs, this maintenance strategy is therefore also referred to as “Run to Failure” (RTF) or “Fit and Forget” (F&F).
  • Many owners do not intentionally allow their assets to run to failure. While they may find that they are neglecting some of their assets, this is not a conscious decision but rather an unfortunate consequence of other factors such as inadequate maintenance budgets, poor planning or ignorance.
  • There is a subtle, but very important, distinction that must be made between Corrective Maintenance (CM) and Reactive Maintenance (RM). In the case of CM, the owners anticipate the consequences of their planned inaction, they are ready for these consequences and they are therefore still in control. In the case of RM, however, the owners are unaware of the consequences of their neglect, they are ill-prepared and the assets are therefore in control of the owners.
In young buildings with new assets, we can expect lower incidents of failure. During this stage in the life cycle of a
building, corrective maintenance may appear (on the surface)  to be a prudent and reasonable approach. However, this is  false economy and owners will find that attempts to defer costs until something breaks will often result in additional costs.




Candidate Assets
Included below is a list of the criteria to be used in determining which assets may be acceptable candidates for a corrective maintenance program
  • Assets that are not maintainable.
  • Assets that are disposable and cheaper to replace than to fix.
  • Small assets without significant financial value.
  • Assets whose downtime is non-critical - that is, the consequence of failure (CoF) are not significant.
  • Assets that are not subject to wear and tear.
  • Assets that are unlikely to fail during the life of the building.
  • Assets that are prone to technological obsolescence.

Evaluation

A. Merits
Listed below are some of the merits and advantages of the corrective maintenance approach.
  • Costs - Lower short-term costs.
  • Staffing - Requires less staff since less work is being done.
B. Limitations
Listed below are some of the disadvantages of the corrective maintenance approach.
  • Costs - Increased long-term costs due to unplanned equipment downtime
  • Collateral Damage - Possible secondary equipment or process damage.
  • Decreased Reliabilility - Neglect of assets may lead to decreased reliability reflected in downtime.
  • Risk - greater risk
The advantages of corrective maintenance can be viewed as a double-edged sword and therefore skill and care is required  when determining which assets should be allowed to run to failure.



Management Principles
Corrective maintenance has a legitimate role to play in the overall maintenance program, albeit a limited one.
  • In order for a Corrective Maintenance (CM) strategy to be considered prudent (in some limited circumstances), assets must meet one or more of the eligibility criteria.
  • The alignment of maintenance styles to individual assets is discussed under maintenance mix.
Alignment of the four different types of maintenance strategies across the asset portfolio on decisions that are risk-based and consider the whole-life of assets will result in a maintenance mix that is in conformity with ISO 55001 standards
Fig. Alignment of the four different types of maintenance strategies across the asset portfolio on decisions that are risk-based and consider the whole-life of assets will result in a maintenance mix that is in conformity with ISO 55001 standards.


Comparing the Maintenance-Repair-Renewal (MRR) trade-offs at different organizations.
Fig. Comparing the Maintenance-Repair-Renewal (MRR) trade-offs at different organizations. As maintenance quality and effort increases so too does the frequency and scope of repairs decrease - however, there is a point of diminishing returns. Do you know where your balance is?


The whole life of assets can be divided into life stages
Fig. The whole life of assets can be divided into life stages - early life, mid-life and late-life, with different maintenance strategies at each life stage.




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Fig. Various samples of the result of deferred maintenance.


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Fig. Excessive vegetation growth on roof.


The risk spectrum extending along the P-F interval to illustrate the varying strategies in the Pre-P and Pre-F periods. For example, a shift from Time-Based Maintenance (TbM) to Condition-Based Maintenance (CbM)
Fig. The risk spectrum extending along the P-F interval.



Fig.  A table comparing how the different
maintenance strategies may approach the same maintenance objective of cleaning roof drains


Correlation of corrective maintenance to preventive maintenance
Fig.  Correlation of corrective maintenance to preventive maintenance.


I. Care is attempting to slow down or reserve the sands of time so that he can undo the deferred maintenance
Fig. I. Care is attempting to slow down or reserve the sands of time so that he can undo the deferred maintenance. A futile but valiant attempt.



Reaching complex decisions can feel like a rollercoaster ride.
Fig. I. Care is nervous because he knows that there are surprises (in the form of a roller coaster ride) if the owners become reactive in their planning.


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I. Care spinning the wheel of misfortune to determine the consequences of deferred maintenance
Fig. I. Care spinning the wheel of misfortune to determine the consequences of deferred maintenance.

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