When is run to failure an acceptable maintenance strategy?
Run to failure can be a deliberate reliability strategy, but only when the consequences are acceptable and the plant knows how it will recover. It should never be used as a blanket excuse for missed inspections or a missing maintenance program.
Evaluate loss of function in context
Start with the asset's required function and credible failure modes. Consider injury risk, environmental impact, regulatory duties, production loss, quality, secondary damage and time to restore. A cheap part may have high consequences if it disables a protective system. A more expensive part may be noncritical if effective redundancy exists and recovery is straightforward.
Check whether a proactive task is effective
Reliability centered maintenance asks whether a technically feasible inspection, condition monitoring task, scheduled restoration or replacement can reduce a specific failure risk. Some failure modes have no useful age relationship and cannot be detected early enough to act. Calendar replacement may add cost and introduce defects without preventing those failures. The choice must be made by failure mode, not by asset name alone.
Document the decision criteria
- Failure has no unacceptable safety, environmental or regulatory consequence.
- Production and quality impacts are within agreed tolerance.
- Secondary damage and recovery time are manageable.
- Parts, labor, access and an approved repair method are available when needed.
- The decision has an owner, evidence, assumptions and a review date.
Hidden protective functions need special treatment. A device may appear healthy until it is demanded, so failure finding tests or redesign can be necessary. Its low purchase price does not make an undetected failure acceptable.
Illustrative example
A noncritical indicator lamp is visibly failed, inexpensive to replace and does not affect safe operation. Replacement on failure may be sensible. A normally dormant high level shutdown device is different: its failure may remain hidden until a dangerous demand. The two cannot share a strategy simply because both are small components.
Prepare for failure and revisit the choice
Document the spare part, lead time, isolation requirements and escalation path. Track actual failure frequency, repair duration and consequences. Reassess when process duty, redundancy or spare availability changes. A defensible run to failure policy is reviewed, traceable and understood by operations.
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