Many RCM guidelines include task selection logic diagrams based on the Failure Effect Categorization. When safety is not an issue, another is to compare normalized cost values for the available maintenance strategies and select the maintenance task that provides the desired level of availability for the minimum cost. For example, if the cost per uptime of performing corrective maintenance only (run to failure) is less than the cost per uptime of performing a scheduled repair/replacement, and the run to failure approach provides an acceptable level of equipment availability (uptime), then the team may recommend no scheduled maintenance tasks for the equipment. An article from ReliaSoft's Reliability Edge newsletter presents a more detailed discussion of how such comparisons might be conducted.
One of the key factors in asset/system performance is its reliability- “inherent reliability” or designed in reliability. Are we designing the system with reliability and maintenance in mind? The O&M cost, which is typically about 80% of the total life cycle cost of the system, becomes fixed –whether intentionally or not- during the early design phase. Are we specifying the reliability and maintenance needs in our requirements document before the design phase begins? The reliability & maintainability are design attributes that should be designed into the assets to minimize maintenance needs by using reliable components, simpler replacements and easier inspections.