Preventive-maintenance impact on plant availability

The relationship between plant availability and preventive maintenance (PM) is examined. It is concluded that unexpected failures that lead to partial or full plant forced outages are costly events that should be avoided. Plant availability is improved (i.e., forced outages are reduced) in one of two ways: maintain or increase equipment MTBF (mean time between failure) and/or reduce its MTTR (mean time to repair). Preventive maintenance actions, when properly executed, can beneficially impact both MTBF and MTTR. Current PM practices are frequently derived from a series of intuitive processes that are not very effective in meeting the PM program objectives. Reliability-centered maintenance is found to be a proven methodology for optimizing the effectiveness of PM programs, and thus recommended as the preferred approach to defining PM tasks