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Reliability Centered Maintenance
Reliability Centered Maintenance (RCM) is a structured approach to optimization of a preventative maintenance program. Originally developed by the airline industry, RCM is based on a few key principles:
- The rigor of maintenance should be appropriate for the consequences of failure.
- Failures should be predicted when cost-effective to do so.
Building on these key principles, and on an understanding of the maintenance process, the practitioner of RCM can develop optimal routine maintenance tasks plus identify selected instances where design or operational practice changes can lead to performance improvement.
RCM, as practiced by Loma Consulting, also includes the process of Performance Feedback and Refinement, which enables the organization implementing RCM to help ensure that the program remains optimal as the company builds experience. RCM and the other tools discussed in this website represent key elements of the Asset Management process. Ideally, Loma Consulting will integrate RCM with enhanced application of the CMMS, data collection techniques, and data mining to provide a comprehensive program.
The RCM philosophy is simple and compatible with standard methods of maintenance program management. Implementing it requires a set of ordered steps. The end result of RCM is an optimal routine maintenance strategy with a documented technical basis. Appropriate discussion and supporting justifications are provided for each decision that is not obvious in nature. Skills learned in conducting RCM studies can be put to use in maintaining an optimal posture for the routine maintenance program over the long term.
The following summarizes the basic steps of RCM, and provides a brief description of the focus of each step.
Select a scope of work for study. RCM is worth doing anywhere a reasonable return on investment is likely. Typically the process is applied to high value equipment, or equipment whose failure has significant system consequences beyond the failure of the equipment itself. Selecting a scope of work that will provide benefits is important to achieve return on investment of study time. The performing organization may wish to prioritize the equipment to be analyzed to maximize the early process gains.
Establish boundaries. This step bounds the study such that the scope of work is clear.
Identify interfaces. Interfaces support the equipment or system, and are assumed available. This further clarifies the scope of the study, and provides information regarding key assumptions. Typically interfaces are assumed to be available include AC and DC power, control signals, and grounding.
Collect maintenance-related data in the form of written records and interviews with knowledgeable personnel to support completion of the study. Some level of maintenance history must be examined in support of completing the study. Usually when written records are not readily available or are of limited value, the study relies on interview with technical personnel to provide insight regarding equipment performance history and maintenance effectiveness. Interviews are necessary in any case, as written records almost never provide complete insights into the equipment.
Determine important functions to preserve. RCM focuses routine maintenance only on functions that are important to preserve. Defining important functions at the beginning of the study helps focus efforts.
Identify dominant failures that fail important functions. Only those equipment failures that are dominant (reasonably likely) are considered in the study. In doing so, only likely failures become the target of routine tasks. This further focuses efforts of the study to cost-effectively defend against credible threats to equipment failure.
Determine criticality of dominant failures. Even if a failure is reasonably likely, its consequences may not warrant consideration of routine maintenance. The determination of criticality helps focus the remainder of the study on failures that are worth defending because of the consequences that can be avoided.
Identify dominant causes of critical equipment failures. As with criticality, the RCM study is only concerned with dominant causes of failure. This helps ensure that only those causes that are reasonably likely to occur will be addressed by routine maintenance. This is a key to making the routine maintenance program cost-effective. Since understanding causes of failure is important for proper task selection, considerable time is spent in this portion of the process.
Select cost-effective routine tasks to directly address dominant causes. Tasks selected must be both technically correct and worth the resources expended in order to be considered cost-effective. A considerable portion of study time is spent performing this portion of the work since it is key to developing a cost-effective overall strategy of routine maintenance. In this portion of the work, all possible alternative routine maintenance strategies are considered. Also, design changes and modification, operating equipment until failure, and changing the manner in which equipment is operated are also viable alternatives to address the causes of critical failure modes. The relative cost-effectiveness of each is an important consideration for task selection.
Select appropriate frequencies for tasks to ensure cost-effectiveness. Just as important as task selection is the assignment of frequency for a task. Often frequency is tied closely to the cause of failure and sometimes a frequency is assigned due to the influence of related tasks that make it more cost-effective to conduct in conjunction with other tasks. Develop a cost-effective routine maintenance strategy by coalescing the results of task selection into a reasonable program that can be implemented cost-effectively. At this point in the process, all tasks and frequencies are considered in light of one another to develop a strategy of routine maintenance. A format, such as a template, can be created to show from a program implementation standpoint how the tasks will be applied.
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