Run-to-Failure(RTF)

Maintenance performed at predetermined intervals or according to prescribed criteria to reduce the probability of failure or functional degradation. Preventive maintenance includes time-based activities (replacement, overhaul, calibration at fixed intervals), usage-based activities (at fixed operating hours or cycles), and condition-based activities (when monitored parameters indicate intervention is needed). The goal is to prevent failures that would otherwise occur.

A maintenance strategy that uses condition monitoring data, analytics, and failure prediction models to determine the optimal timing for maintenance intervention. Predictive maintenance aims to perform maintenance just before failure is expected, maximizing equipment life while minimizing unplanned downtime. It goes beyond condition monitoring by adding prediction — estimating the remaining useful life based on degradation trends.

The assignment of a criticality ranking (typically A, B, or C) to each equipment item based on the consequences of its failure across safety, environmental, production, and maintenance cost dimensions. Criticality classification determines the level of engineering attention, inspection rigor, maintenance strategy, and spare parts investment appropriate for each asset.

A failure that occurs with approximately constant probability per unit time, independent of the item's age or accumulated operating time (Weibull beta approximately 1). Random failures are caused by unpredictable combinations of stress and strength, external events, or operating conditions that cannot be anticipated by age-based inspection or maintenance. They are equally likely to occur at any point during the useful life period.