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Inner secrets
OMDEC's inner secrets and strategies on reliability analysis, knowledge management, and CBM optimization can be found here.
Potential failure
Potential failure: an indicated failure that has clearly initiated and is in the process of deteriorating to become a functional failure that may have safety, environmental, operational, or major economic consequences.
Three ways in which a component's life-cycle may end
An item may be removed or reworked as the result of a scheduled task, or because it was expedient to do so at that particular time. Such an event would be an "ending by suspension" or “ES” event. If the item no longer performs as required (a functional failure), or, if failure was imminent (a potential failure), those events would be consiered as "endings by failure" or “EF”. EF would also include a "partial" functional failure - the item is still operational but cannot meet the user's requirements.
Hidden failures and Multiple failures
Hidden Failure: A failure of a protective function, e.g. a safety limit switch, that would normally go undiscovered until the function that it was protecting, e.g. a high level limit switch, also fails.
Multiple Failure: A failure of a protected function at a time when its protective function is already in a failed state.
The origin of reliability-centered maintenance
Report AD-A066-578, “Reliability-Centered Maintenance”, F. Stanley Nowlan, Howard F. Heap, National Technical Information Service, U.S. Department of Commerce, 1978
EXAKT and the potential failure
For many failure modes the measurement level at which a potential failure is declared is based on judgment and experience. The EXAKT methodology recognizes the probabilistic nature of a potential failure and therefore defines a “best” decision (way of setting an action limit) based on a stated long-run optimizing objective.
What is proportional hazard modeling?
The PHM (proportional hazard model) extends the age based reliability model developed by Walodi Weibull in the 1950’s to one developed by Cox in the 1970’s that adds condition monitoring and performance data to the age-reliability relationship.
The reliability knowledge elements
We use the expression “knowledge element” interchangeably with the phrase “RCM question” in order to emphasize that knowledge drives decisions to do the right maintenance at the right time. The 7 knowledge elements constitute the framework of our reliability centered knowledge to be physically enshrined in our CMMS.
Applicable and effective tasks in maintenance.
Applicable: A task is technically feasible. Effective: A task accomplishes the intended objective
Age Exploration, Relaibility aAnalysis, and Reliability-centered maintenance analysis
Age Exploration: Any analysis procedure that examines historical maintenance data in order to alter the maintenance plan for improved physical asset reliability.
Items and significant items
Item: A group of one or more parts or assemblies that is convenient to treat as a single entity for reliability analysis. Items are defined at a high enough level of indenture so that their failures may be clearly related to failure of the equipment as a whole. (See Appendix 3. Sizing the analysis page 283.)
Significant item: An item whose failures:
· Are not evident under normal circumstances, or
· Can directly negatively impact safety or the environment, or
· Can have direct major economic or operational impact.