reliability centered maintenance

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When working for Petrobras at PRSI (Pasadena Refining System Inc.) I had this opportunity to share my experience as a Maintenance Manager in Brazil with PRSI operators and maintenance crew.


  • 1. Reliability CenteredMaintenance (RCM)
  • 2. Evolution of MaintenanceAt the very beginning, Maintenance was an appendix to Operations / Production: It existed only to fix failures, when they happened. These were the days of absolute Corrective Maintenance
  • 3. Evolution of MaintenanceAs times went by, it was detected that many failures have an almost regular pattern, failing after anaverage period. Therefore, one could choose regular intervals to fix the equipment BEFORE the failure: Preventive Maintenance Also know as Time Based Maintenance.
  • 4. Evolution of Maintenance However, very often these failures happen in irregular periods. To avoid an unwanted failure, the periods of Preventive Maintenance are shortened. If equipmentconditions were known, the maintenance could be later. Technology development enabled to identify failure symptoms: Predictive Maintenance Also know as Condition Based Maintenance.
  • 5. Evolution of Maintenance Many pieces of equipment have sporadic activity (alarms,stand-by equipments, etc.). However, we must be sure thatthey are ready to run. These are "hidden faults. Detect and prevent hidden failure is called: Detective Maintenance
  • 6. Evolution of MaintenanceThe different failure modes mean that theres notone only approach, about Corrective, Preventive orPredictive Maintenance Programs.The correct balance will give in return betterequipment reliability, thus the name:Reliability Centered Maintenance Take it easy, Remember, my grandma, not kid, Prevention always! is better than Cure....
  • 7. Reliability Centered Maintenance (RCM)John Moubray 1949-2004After graduating as a mechanical engineer in 1971, John Moubray workedfor two years as a maintenance planner in a packaging plant and for oneyear as a commercial field engineer for a major oil company.In 1974, he joined a large multi-disciplinary management consultingcompany. He worked for this company for twelve years, specializing in thedevelopment and implementation of manual and computerizedmaintenance management systems for a wide variety of clients in themining, manufacturing and electric utility sectors.He began working on RCM in 1981, and since 1986 wasfull time dedicated to RCM, founding Aladon LCC, whichhe led until his premature death in 2004.John Moubray is today considered a synonym of RCM.
  • 8. Reliability Centered Maintenance (RCM) Its originsWhat about a failure rate of 0.00006/event?Quite good, no?This was the average failure rate in commercial flightstakeoffs, in the 50s. Two thirds of them caused byequipment failures.Today, this would mean 2 accidents per day, withplanes with more than 100 passengers!!!Thats why Reliability Centered Maintenance has begunin the Aeronautical Engineering. Pretty soon, Nuclearactivities, Military, Oil & Gas industries also began touse RCM concepts and implement them in theirfacilities.
  • 9. Reliability Centered Maintenance (RCM) Reliability and Availability Reliability Reliability is a broad term that focuses on the ability of a product to perform its intended function. Mathematically speaking, reliability can be defined as the probability that an item will continue to perform its intended function without failure for a specified period of time under stated conditions. Reliability is a performance expectation. Its usually defined at design. Availability Depends upon Operation uptime and Operating cycle. Availability is a performance result. Equipment history will tell us the availability.Bibliography: Kardec, Alan y Nascif, Julio - Manuteno- Funo Estratgica, Editora Qualitymark
  • 10. Reliability Centered Maintenance (RCM) Reliability and Availability MTBF = Mean Time Between Failures MTTR = Mean Time To Repair A first definition: MTBFAvailability = MTBF + MTTRBibliography: Kardec, Alan y Nascif, Julio - Manuteno- Funo Estratgica, Editora Qualitymark
  • 11. Reliability Centered Maintenance (RCM) Availability definitions MTBF = Mean Time Between Failures MTTR = Mean Time To Repair MTBM = Mean Time Between Maintenance actions M = Maintenance Mean Downtime (including preventive and planned corrective downtime) Inherent Availability: consider only corrective downtime Achieved Availability: consider corrective and preventive maintenance Operational Availability: ratio of the system uptime and total time MTBF Inherent Availability = MTBF + MTTR MTBM Achieved Availability = MTBM + M UptimeOperational Availability = Operation Cycle
  • 12. Reliability Centered Maintenance (RCM) Reliability and Availability 250 days 360 days 200 days 120 days = 947 days Downtime 9d 6 2 MTBF = (250 + 360 + 200 + 120) / 4 = 232.5 days MTTR = (9 + 6 + 2) / 3 = 5.67 days Availability = 232.5 / (232.5 + 5.67) = 97.62 % 180 days 400 days 120 days 233 days = 947 daysDowntime 7 4 3 MTBF = (180 + 400 + 120 + 233) / 4 = 233.25 days MTTR = (7 + 4 + 3) / 3 = 4.67 days Availability = 233.25 / (233.25 + 4.67) = 98.04 %
  • 13. Reliability Centered Maintenance (RCM) Reliability and Availability Achieved Availability = MTBM/ (MTBM+M)To improve Availability:Improve MTBM:Reduce Preventive Programs to a minimum, or, have Preventive intervals as welldefined as possible.Using Predictive techniques whenever possibleImplementing Maintenance Engineering (RCM, TPM...)Minimize M:Implementing Maintenance Engineering (Planning, Logistics...)Improving personnel technical skills (training)Developing Integrated Planning (Mntce+Ops+HSE+Inspection+...) Bibliography: Kardec, Alan y Nascif, Julio - Manuteno- Funo Estratgica, Editora Qualitymark
  • 14. Reliability Centered Maintenance (RCM) Improving ProductivityProductivity Improvement Factors: Detailed work planning Delivering equipments to Maintenance as clean as possible Check-list at the end of Maintenance activities Complete and comprehensive Equipment data available Supplies available on job site Skilled personnel Bibliography: Kardec, Alan y Nascif, Julio - Manuteno- Funo Estratgica, Editora Qualitymark
  • 15. Reliability Centered Maintenance (RCM) Availability benchmark


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