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RCM

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RCM

  1. 1. Reliability Centered Maintenance 1
  2. 2. 2 Reliability Centered Maintenance Presented by:- Eng. Mohammed Hamed Reliability Centered Maintenance
  3. 3. Reliability Centered Maintenance 3 Content: 1. Introduction to RCM and Criticality Analysis 2. Intorduction to Failure Modes and Effect Analysis FMEA 3. The Steps of FMEA 4. A Case of Reliable Improvement by Increasing Detection 5. A Case of Reliable Improvement by Re Desiging the System
  4. 4. Reliability Centered Maintenance 4 RCM Reliability Centered Maintenance The RCM philosophy employs Preventive Maintenance (PM), Predictive Testing and Inspection, Repair (also called reactive maintenance) and Proactive Maintenance techniques in an integrated manner to increase the probability that a machine or component will function in the required manner over its design life cycle with a minimum of maintenance. The goal of the philosophy is to provide the stated function of the facility, with the required reliability and availability at the lowest cost. RCM requires that maintenance decisions be based on maintenance requirements supported by sound technical and economic justification.
  5. 5. A rigorous RCM analysis is based on a detailed Failure Modes and Effects Analysis (FMEA) and includes probabilities of failure and system reliability calculations. The analysis is used to determine appropriate maintenance tasks to address each of the identified failure modes and their consequence As with any philosophy, there are many paths, or processes, that lead to a final goal. This is especially true for RCM where the consequences of failure can vary dramatically. Rigorous RCM analysis has been used extensively by the aircraft, space, defense, and nuclear industries where functional failures have the potential to result in large losses of life, national security implications, and/or extreme environmental impact. Reliability Centered Maintenance 5 Equipment or Maintenance Reliability Definition: The instantaneous likelihoods of failure for a specific piece of equipment during a specific time period.
  6. 6. RCM Analysis The RCM analysis carefully considers the following questions: • What does the system or equipment do; what is its function? • What functional failures are likely to occur? • What are the likely consequences of these functional failures? • What can be done to reduce the probability of the failure, identify the onset of failure, or reduce the consequences of the failure • To ensure realization of the inherent safety and reliability levels of the equipment. • To restore the equipment to these inherent levels when deterioration occurs. • To obtain the information necessary for design improvement of those items where their inherent reliability proves to be inadequate. • To accomplish these goals at a minimum total cost, including maintenance costs, support costs, and economic consequences of operational failures. RCM Goals Reliability Centered Maintenance 6
  7. 7. Reliability Centered Maintenance 7 Reliability centered maintenance (RCM) is a reliability tool that is used to ensure the inherent designed reliability of a process or piece of equipment through the understanding and discovery of equipment functions, functional failures, failure modes and failure effects. In performing a RCM analysis, the RCM team uses a structured decision process to develop mitigating tasks for each failure mode identified during the analysis.
  8. 8. Indentify System & Boundary Indentify Sub System and Components Examine Function Identify Consequence of Failure Define Failure & Failure Mode ------------------------ •System Input •System Output •Resources •Constraints To what level? •Inconsequential •Primary or Support •Continuous or Intermittent •Active or Passive Failures: •Hidden Failures •Potential Failures Environmental, Health & Safety Operational/Mission •Availability •Quantity •Quality ●Cost ------------------------ ------------------------ ------------------------ ----------------------- Reliability Analysis Reliability Centered Maintenance 8
  9. 9. Will the failure have a direct effect on environment health or safety Is there an effective PdM technology or approach? Develop & schedule PdM task to measure condition Develop Condition Based Task Will the failure have a direct & adverse effect on mission quantity or quality? Will the failure result in other economic losses (high cost damage to equipment or system) No Candidate For Run to Failure Is there an effective Interval Based Task Develop & schedule Interval Based Task Re design system or accept the failure risk No Yes Yes Yes No No Yes Yes Maintenance Analysis No Reliability Centered Maintenance 9
  10. 10. Will the failure of the system or equipment item have a direct & adverse effect on safety or critical mission function Is this item expendable Can redesign solve the problem effectively and cost effective Accept Risk Is there a PdM technology that will monitor condition and give sufficient warning of an impending failure Redesign Is PdM cost and priority justified Define PdM task and schedule Is there an effective PM task that will minimize functional failure Define PM task and schedule Is installed redundant cost and priority justified Install Redundant Unit Yes Yes Yes Yes Yes Yes No No No No No No No Yes Abbreviated decision tree used to identify the maintenance approach Reliability Centered Maintenance 10
  11. 11. RCM Employs all Maintenance Policies Maintenance Policies Failure Based Reactive RTF/FF CM Redundancy Non- Critical Risk Based Preventive Calendar Semi Annually Quarterly Monthly Daily/ Weekly Time Based Proactive RCFA FMEA RBI Condition Based Predictive Thermal Vibration Oil Ultrasound Wear Effeciency Pressure Motor Current Reliability Centered Maintenance 11
  12. 12. Predictive Maintenance Embraced by Plant Maintenance Technique Application Pumps Electric Motors Diesel Generators Condensers Heavy Equipment/ Crane Circuit Breakers Valves Heat Exchangers Electrical Systems Transformers TankPiping VIB Analysis • • • • Oil Analysis • • • • • Wear Analysis • • • • IR Analysis • • • • • • • • • • • Ultrasound • • • • • • • • • Non-Destructive testing (Thickness) • • • Visual Inspection • • • • • • • • • • • • Motor Current Analysis • Reliability Centered Maintenance 12
  13. 13. Reliability Centered Maintenance 13
  14. 14. Reliability Centered Maintenance 14
  15. 15. KPI Description MTBF Mean Time Between Failure No of failures addressed by root cause analysis >75% Ratio of PM work orders to CM work orders generated by PdM inspection OEE (Overall Equipment Effectiveness) Availability x Reliability x Quality (85%) Percent of Faults Found in Predictive maintenance Survey (Vib, IR, UT, OA) No of faults found/ No of devices checked (target <3% Percent of equipment covered by condition monitoring Target= 100% Reliability of critical equipment 99% Facility Availability >98% Availability of critical equipment >98% Percent emergency maintenance <5% Percent planned maintenance 90% Reliability KPIs Reliability Centered Maintenance 15
  16. 16. Reliability Centered Maintenance 16
  17. 17. Importance of Equipments Criticality Analysis: • Influence the priority assignment of the Work Orders. • Influence the Work Orders execution speed. • Determine which Maintenance Class should come first. • Effect the scheduling of the preventive maintenance program. • Influence the priority of the preventive maintenance work. • Help in determining which maintenance approach to be used. Reliability Centered Maintenance 17
  18. 18. Reliability Centered Maintenance 18 Eq Criticality Measuring Principles: Safety Safety equipments (equipments carrying peoples, fire fighting system,….etc). Consequence of parts failure effect safety (elevator ropes broken, fire fighting generator stopped…etc). Gas piping leakage at any point poses a risk.
  19. 19. Snappy Cables Shock Absorber 19Reliability Centered Maintenance Safeties are the braking system in the elevator.
  20. 20. Criticality decreases with redundancy in the system. Production, Process Equipment breakdown affect the whole production line. Equipment breakdown affect partially the production line. Equipment failure has native effect on production quality. Criticality is Influenced by the availability of standby equipment in a system But how much time does it take for the standby equipment to operate? And what is the effect of this on the production? Reliability Centered Maintenance 20
  21. 21. Time (Time=Money) 1 min production=How much? 1 Hr production =How much? If your equipment is classified as critical, ask yourself the following questions: • What is the preventive maintenance program I have for it? Enough? Or not? • How much time does it take to repair it in case of failure? • Spare parts allocation? Available? Not available?....If not available, how much does it take to allocated it from the vendor? • Require special skills for repair? Is my team trained to repair it in a proper time? • Do you have an emergency plan for it in case of accident or failure? Is your team aware of this plan and trained on it? Reliability Centered Maintenance 21
  22. 22. Reliability Centered Maintenance 22 Money, Cost
  23. 23. Reliability Centered Maintenance 23
  24. 24. A proactive tool to minimize the risk of failures and improve reliability Reliability Centered Maintenance 24
  25. 25. Reliability Centered Maintenance 25 FMEA can provide the answer to many problems: •How can we prevent this problem from occurring again in the future? •How can we minimize the risk of this potential failure? •How can we produce an error-free product? •How can we reduce the warranty costs? •How can we improve the safety condition in the workplace?
  26. 26. What is Failure Mode Effect Analysis FMEA? An FMEA is a systematic method for identifying and preventing product and process problems before they occur. FMEAs are focused on preventing defects, enhancing safety and increasing customer satisfaction. FMEAs are conducted in the product design or process development stages, although conducting an FMEA on existing products and processes can also yield substantial benefits. What is the purpose of a FMEA? Preventing the process and product problems before they occur is the purpose of Failure Mode Effect Analysis. Used in both the design and manufacturing process, they substantially reduce costs by identifying product and process improvement early in the develop process when changes are relativity easy and inexpensive to make. Reliability Centered Maintenance 26
  27. 27. FMEA as a part of a Comprehensive Quality System Can FMEA be used a lone? While FMEAs can be effectively used a lone, a company won’t get maximum benefit without systems to support conducting FMEAs. Two things are necessary needed: 1. A reliable product or process data. Without this data, FMEA becomes a guessing game based on opinions rather than actual facts. Without data the team may focus on the wrong failure modes or missing significant opportunities to improve the failure modes that are the biggest problems. 2. Documentation of procedures. In the absence of documents and procedures, people working in the process could be introducing significant variation in to it by operating it slightly different each time the process is run. Reliability Centered Maintenance 27
  28. 28. Reliability Centered Maintenance 28 FMEA is one of the ISO 9001:2000 requirements as you must have a system capable of controlling process that determine the acceptability of your product or services.
  29. 29. Benefits of Failure Modes Effect Analysis “FMEA” The object of an FMEA is to look for all of the ways a process or product can fail. A product failure occurs when the product does not function as it should or when it malfunction in some way. •Contribute to improve design for product & process. -Higher reliability -Better Quality -Increase Safety •Contribute to cost saving. -Decrease development time & redesign cost -Decrease warranty costs. -Decrease wastes •Contribute to continuous improvement. Reliability Centered Maintenance 29
  30. 30. Reliability Centered Maintenance 30 • System FMEA focuses on global system functions. • Design FMEA focuses on components and subsystems. • Process FMEA focuses on manufacturing and assembly processes. • Service FMEA focuses on service functions. Apply to: System, Process, Design, Service Service engineers use FMEA to improve the lifecycle of the product and lower its service costs by developing a proper maintenance program. FMEA helps manufacturing engineers control the process and eliminate errors during production, thus decreasing warranty costs and wastes.
  31. 31. Potential Applications: •Equipment components & parts. •Component proving process. •Outsourcing/resourcing of product. •Develop suppliers to achieve quality. •Major process/ Equipment / Technology. •Changes. •Cost Reductions. •New Product/ Design Analysis •Assist in analysis in a flat Pareto chart. Reliability Centered Maintenance 31
  32. 32. Failure Modes: •Any event which causes a functional failure. Example failure modes: •Bearing Seized •Motor burned out •Coupling broken •Impeller jammed Compressors Failure Modes : •Discharge pressure low -Air leakage -leaking valves -Defect gauge Engines Failures Mode: •Knocking -Pistons hitting the head -Crankshaft plays -Oil pump not function Reliability Centered Maintenance 32 •Ways in which product or process can fail are called failure modes. The FMEA is a way to identify the failures, effects, and risks within a process or product, and then eliminate or reduce them.
  33. 33. Even the simple products have many opportunities for failure. For example, a drip coffee maker. A relativity simple household appliance-could have several things fail that would render the coffeemaker inoperable. Here are some ways the coffee make can fail: • The heating element doesn’t heat water to sufficient temperature to brew coffee. • The pump doesn’t pump water into the filter basket. • The coffee maker doesn’t turn on automatically by the clock • The clock stops working or running too fast or too slow. • There is a short in the electrical cord. • There is either not enough or too much coffee used. Reliability Centered Maintenance 33
  34. 34. Reliability Centered Maintenance 34
  35. 35. Reliability Centered Maintenance 35 Failures are not limited to problems with the product. Because failures also can occur when the user makes a mistake. Those types of failures should be included in the FMEA. Anything can be done to ensure the product works correctly, regardless of how the user operates it, will move the product closer to 100 percent total customer satisfaction. The use of mistake-proofing techniques, also known by its Japanese term poka-yoke, can be a good tool for preventing failures related to user mistakes. The goal is
  36. 36. The failure effect as it applies to the item under analysis. Ex. Water pump stop The failure effect as it applies at the next higher indenture level. Ex. Water system pressure drop down. The failure effect at the highest indenture level or total system. Ex. System stop. Local Effect Next Higher Effect End-Effect Failure Effects Description Reliability Centered Maintenance 36
  37. 37. The team size should be between 4 to 6 persons. But the number of people is dedicated by the number of areas affected by the FMEA for example (manufacturing, maintenance, design, engineering, material, technical service…etc). The customer add another unique perspective and should be considered for team membership. Team Leader: The team leader is responsible for coordinating the FMEA process as follow: 1. Setting up and facilitate meeting. 2. Ensuring the team has the necessary resources available. Reliability Centered Maintenance 37
  38. 38. Reliability Centered Maintenance 38 3. Making sure the team is progressing toward the completion of the FMEA process. 4. The team leader role is more like of a facilitator rather than decision maker.
  39. 39. Reliability Centered Maintenance 39  Determine the boundaries of freedom  Define the scope of the project
  40. 40. Reliability Centered Maintenance 40 Select a high-risk process, then follow these steps. 1. Review the process: this step usually involves a carefully selected team that includes people with various job responsibilities and levels of experiences. The purpose of an FMEA team is to bring a variety of perspectives and experiences to the project. 2. Breakdown the system into components and sub-components. 3. Brainstorm potential failure modes. 4. List potential effects of each failure mode. 5. Assign a severity ranking for each effect. 6. Assign an occurrence ranking for each failure mode. 7. Assign a detection ranking for each failure mode. 8. Calculate the risk priority number (RPN) for each effect. 9. Prioritize the failure modes for action using RPN. 10. Take action to eliminate or reduce the high-risk failure modes. 11. Calculate the Resulting RPN as the failure modes are reduced or eliminated. Steps of FMEA Process :
  41. 41. Reliability Centered Maintenance 41 FMEA Working Sheet Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN Component/Item Name: Function :
  42. 42. Step.1 Review the Process or Product Reliability Centered Maintenance 42 If the team is considering a product, they should review the engineering drawing of the product. If the team considering a process, they should review the operation flowchart. This is to ensue that everyone has the same understanding about the process or product. For a product, they should physically see the product and operate it. For a process, they should physically walk through the process exactly as the process flows.
  43. 43. Reliability Centered Maintenance 43 Step.2 Breakdown the system into components and sub-components If the system is a large system, like a water system that supplies an industrial process, the pump can be a critical component inside the system. A motor pump is a critical subcomponent because its failure can break down the entire process. The motor pump should be broken down into more subcomponents that are likely to fail and will affect the system, such as the motor’s bearings and the rotor shaft. The FMEA will be used to prevent the probability of failure for each component or subcomponent.
  44. 44. Step.3 Brain Storm Potential Failure Modes Reliability Centered Maintenance 44 Once everyone in the team has an understanding about the product or the process, team members should begin thinking about the potential failure modes that could affect the manufacturing process or the product quality. Focusing should be on the different elements (people, material, equipment, method,…etc). Once the brainstorming is completed, the ideas should be organized by grouping them into like categories. There are many ways to group failure modes, they can be grouped by type of failure (electrical, mechanical, user created). Where on the product or process the failure occurs.
  45. 45. Reliability Centered Maintenance 45 Main Rules of Brainstorm: 1. Do not comment on, judge or critique ideas at the time they are offered. 2. Encourage creative and offbeat ideas. 3. The goal is to end up with a large number of ideas; and evaluate ideas later. 4. Each idea should be listed and numbered exactly as offered, on a flip chart. 5. Expect to generate at least 50 to 60 concepts in a 30-minute brainstorming session.
  46. 46. Failure Mode & Effect Analysis FMEA -How can this sub system fail to perform its function? -The Way the failure occurred -What will the operator see? Reliability Centered Maintenance 46 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  47. 47. Step.4 List Potential Effects for Each Failure Mode Reliability Centered Maintenance 47 For some of the failure modes, there may be one effect, while for other modes, there may be several effects. This information must be through because it will feed into the assignment of the risk ranking for each of the failure. Tips: 1. One failure mode could have several effects. For example, an electrical cutoff in the home could stop the refrigerator and damage food or prevent you from doing work on the computer. 2. Several failure modes could have one effect. A dead car battery or tire failure has the same effect on your vehicle – it will be difficult to make it to work on time with such a failure early in the morning. 3. The team must determine the end-effect each failure mode has on the system or the process. This means examining how each failure affects the entire system, the facility or the other connected processes.
  48. 48. Failure Mode & Effect Analysis FMEA -What happen when failure mode occurs? -Immediate consequences of a failure on operation, function or functionality, or status of some item. Reliability Centered Maintenance 48 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  49. 49. Steps 5-7 Assign Severity, Occurrence, and Detection Rankings Reliability Centered Maintenance 49 Each of these three rankings is based on 10-point scale, with 1 being the lowest ranking, and 10 the highest.
  50. 50. Failure Mode & Effect Analysis FMEA Effect of failure is determined by the worst case outcome with respect to safety and environment impact, production availability and direct economic cost and all that in numerical measure which are identified from ranking criteria Reliability Centered Maintenance 50 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  51. 51. Failure Mode & Effect Analysis FMEA Safety and Environment severity degree Impact degree on availability of Production Impact degree on Cost Reliability Centered Maintenance 51 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  52. 52. Description of Failure Effect Effect Ranking No reason to expect failure to have any effect on Safety, Health, Environment or Mission. None 1 Minor disruption of production. Repair of failure can be accomplished during trouble call. Very Low 2 Minor disruption of production. Repair of failure may be longer than trouble call but does not delay Mission. Low 3 Moderate disruption of production. Some portion too of the production process may be delayed. Low to Moderate 4 Moderate disruption of production. The production process will be delayed. Moderate 5 Moderate disruption of production. Some portion of production function is lost. Moderate delay in to High restoring function. Moderate to High 6 High disruption of production. Some portion of production function is lost. Significant delay in restoring function. High 7 High disruption of production. All of production function is lost. Significant delay in restoring High function. Very High 8 Potential Safety, Health or Environmental issue. Failure will occur with warning. Hazard 9 Potential Safety, Health or Environmental issue. Failure will occur without warning. Hazard 10 Severity Ranking Criteria Reliability Centered Maintenance 52
  53. 53. Reliability Centered Maintenance 53 Step.6 Assign an occurrence ranking for each failure mode The best method for determining the occurrence ranking is to use actual data from the process. This may be in the form of failure logs. When actual failure data are not available, the team must estimate how often a failure mode may occur, The team can make better estimate on how likely a failure mode is to occur and at what frequency by knowing the potential cause of failure. Once the potential causes have been identified for all of the failure modes, an occurrence ranking can be assigned even if the failure data are not exist.
  54. 54. Failure Mode & Effect Analysis FMEA For each failure mode there may be several failure causes. Assign a Cause for each failure mode. Select only potential failure to get failure causes. Use Why Why Technique to get the root causes. Identifying the failure cause can be the second option to determine the occurrence if no data is available in the form of failure logs. Reliability Centered Maintenance 54 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  55. 55. Failure Mode & Effect Analysis FMEA The probability of failure Occurrence during the expected life of the system “potential occurrence” Reliability Centered Maintenance 55 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  56. 56. Rank Freq Description 1 1/10,000 Remote probability of occurrence; unreasonable to expect failure to occur 2 1/5,000 Low failure rate; similar to past design that has, in the past, had low failure rates for given volume or load 3 1/2,000 Low failure rate; similar to past design that has, in the past, had low failure rates for given volume or load 4 1/1000 Occasional failure rate; similar to past design that has, in the past, had similar failure rates for given volume or load 5 1/500 Moderate failure rate; similar to past design that has, in the past, had moderate failure rates for given volume or load 6 1/200 Moderate failure rate; similar to past design that has, in the past, had moderate failure rates for given volume or load 7 1/100 High failure rate; similar to past design that has, in the past, had high failure rates that have caused problems 8 1/50 High failure rate; similar to past design that has, in the past, had high failure rates that have caused problems 9 1/20 Very High failure rate; almost certain to cause Problems 10 1/10 Very High failure rate; almost certain to cause Problems Occurrence Ranking Criteria Operating hours based on the automotive industry benchmark. Ranking can be determined based on historical data or similar system benchmarking Reliability Centered Maintenance 56
  57. 57. Reliability Centered Maintenance 57 Step.7 Assign a detection ranking for each failure mode and/or effect First, the current control should be listed for all of the failure modes, or effects , and then the detection rankings assigned. *If one failure mode or effect has several causes, detection and occurrence rankings should be assigned based on these causes. When potential causes are eliminated, the risk of failure is lowered.
  58. 58. Current control/fault detection methods applied to detect this failure. This will help assign the detection ranking. Each detection method should be assigned for each failure mode or effect. Reliability Centered Maintenance 58 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  59. 59. Failure Mode & Effect Analysis FMEA Probability that a failure of mode will be Detected using the control methods that are in place. Reliability Centered Maintenance 59 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  60. 60. Rank Description 1-2 Very high probability of detection 3-4 High probability of detection 5-7 Moderate probability of detection 8-9 Low probability of detection 10 Very low probability of detection Detection Ranking Criteria Reliability Centered Maintenance 60
  61. 61. Step.8 Calculate the Risk Priority Number RPN Reliability Centered Maintenance 61 Risk Priority number= Severity x Occurrence x Detection This number alone is meaningless because each FMEA has a different number of failure modes and effects. However, it can serve as a gauge to compare the revised RPN once the recommended actions has been instituted.
  62. 62. Failure Mode & Effect Analysis FMEA Risk Priority Number Calculation Occurrence X Severity X Detection RPN= O x S x D Reliability Centered Maintenance 62 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  63. 63. RPN Calculation Benefits: •Contribute in Risk Assessment. •Compare components to determine priority for corrective action. What is RPN? The Risk Priority Number (RPN) methodology is a technique for analyzing the risk associated with potential problems identified during a Failure Mode and Effects Analysis (FMEA) Reliability Centered Maintenance 63
  64. 64. Assessing the risk priority number. Each potential failure mode or effect is rated in each of these three factors on a scale ranging from 1 to 10. By multiplying the ranking a risk priority number RPN can be determined for each potential failure mode and effect. The RPN will range from 1 to 1000 for each failure mode. It is used to rank the need for corrective action. Those failure modes with the highest RPN number should be attended first. Although the special attention should be given when the severity ranking is high from (9 to 10) regardless of the RPN. Once a corrective action is takes, a new RPN is determined . This new RPN is called the resulting RPN. Reliability Centered Maintenance 64
  65. 65. Step.9 Prioritize the Failure Modes for Action Reliability Centered Maintenance 65 Failure modes should be prioritized by ranking them in order, from the highest risk priority number to the lowest. Chances are that you will find that the rule 80/20 rule applied with the RPNs. The team must now decided which item to work for. Usually it helps to set a cutoff RPN (cutoff point), where any failure modes with an RPN above that point are attended to. Those below the cutoff are left alone for the time being. Tip: High-risk numbers should be given attention first; then you can pay attention to the severity rankings. Thus, if several failure modes have the same risk priority number, that failure mode with the highest severity should be given more priority.
  66. 66. Failure Mode & Effect Analysis FMEA Appropriate maintenance action, appropriate maintenance task Corrective actions may include: reduce the severity of occurrence ,or increase the detection probability Reliability Centered Maintenance 66 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN
  67. 67. Step.10 Take Actions to eliminate or Reduce the High-Risk Failure Modes Reliability Centered Maintenance 67 This is organized using the problems-solving approaches and implement actions to reduce or eliminate the high risk failure modes. Often the easiest way to make an improvement to the product or process is to increase the detectability of the failure, thus lowering the detection rate. Increase the detection rate can be done though assigning a schedule PM action, use a proper condition monitoring program or consider a mistake proofing method in the design. For example, ac computer software will automatically warn incase of low disk space.
  68. 68. Reliability Centered Maintenance 68 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN Appropriate actions taken to reduce the risk of failure
  69. 69. Reliability Centered Maintenance 69 Step.11 Calculate the Risk Priority Number RPN as the High Risk is Removed Once actions have been taken to reduce the risk priority number, a new ranking for the severity, occurrence, and detection should be calculated. And a resulting RPN is calculated. Expectation is at least 50 percentage reduction in RPN with the FMEA approach. There will always be a potential for failure modes to occur. The question the company must ask is how much relative risk the team is willing to take. That answer might depend o the industry and the seriousness of the failure. For example, in the nuclear industry, there is a little margin for errors,; they can’t risk a disaster occurring. In other industries, it may be acceptable to take the high risk.
  70. 70. Reliability Centered Maintenance 70 Item Function Failure Mode Failure effect Severity Failure Cause occurrence Current Controls Detection RPN Recommendation Take action Resulted S O D RPN NEW RPN based on the new Severity, Occurrence, and Detection rankings
  71. 71. Reliability Centered Maintenance 71 Failure mode Failure Effect Failure Effect (System) Failure Effect (End) Failure cause Level 1 Root cause Fan operate with high vibration level Equipment damage/breakdown Unexpected plant shutdown Major production losses Bearing fails Poor Maint Equipment damage/breakdown Unexpected plant shutdown Major production losses Housing wear Poor Maint Equipment damage/breakdown Unexpected plant shutdown Major production losses Unbalance fan blade Poor Maint Equipment damage/breakdown Unexpected plant shutdown Major production losses Looseness in foundation Poor Maint Equipment damage/breakdown Unexpected plant shutdown Major production losses Shaft wear Poor Maint
  72. 72. Item name Failure mode Failure Effect (local) Failure Effect (System) Failure cause Failure Cause Root cause Oil 1.Short circuit in transformer Functional stop Production losses Particles in the oil Overheated Bad Maintenance Functional stop Production losses Water in the oil Overheated Bad Maintenance Aging Tap Changes 2-Can’t change voltage level Functional stop Production losses Mechanical damage Wear Life time/ maintenance Ex.2 Transformer Reliability Centered Maintenance 72
  73. 73. Ex.3 Water System Function Functional failure/failure modes Causes Provide water to the industrial process Total loss of pressure, volume & flow Pump failed Motor failed Valve out of position Electric Motor Function Functional failure/failure modes Causes Drive the water pump Burn out Circuit Breaker tripped Bearing seized Insulation Rotor Insulation Stator Failure mode Failure Cause Sources of failure/causes Causes Bearing seized, this include bearing, seals, lubrication Lubrication Contamination Supply dirty Sealing failed Wrong type Procedure wrong Supply information wrong Tool little Human error Procedure error Too much Human error Procedure error Motor Bearing Reliability Centered Maintenance 73
  74. 74. Failure effect Severity Causes Root Cause Occurrence Current fault detection methods Detection RPN Actions Local sys end S A C Seal failed Seal failed Motor shutdown System shutdown TPL Procedure wrong Lack of trainingHuman error Human error Final Table Reliability Centered Maintenance 74
  75. 75. Consequence or Severity Probability or frequency (1) Low (2) Medium (3) High (1) Low (2) Medium (3) High 1 L 2 L 3 M 6 H 4 M 2 L 9 H 6 H 3 M It’s important to design your own matrix Risk=Probability x Severity Reliability Centered Maintenance 75
  76. 76. Reliability Centered Maintenance 76 Read the publication here URL: http://www.iienet2.org/details.aspx?id=37883
  77. 77. Reliability Centered Maintenance 77
  78. 78. Reliability Centered Maintenance 78
  79. 79. Reliability Centered Maintenance 79
  80. 80. Electric Distribution Transformer for Glass Furnace Equipment Information Equipment Type : Distribution Transformer Technical Specs : 11KV, 2.5KV Function : Transform electric voltage from 11KV to 400V System : Electric station- Supply Glass Furnaces Availability of standby system: Generators Working intervals : 1-2 seconds Effectiveness : Avoid furnace damage, but medium productivity Reliability Centered Maintenance 80
  81. 81. Reliability Centered Maintenance 81 The electric transformer is considered critical because a failure causes high production losses – $5,000 an hour. A standby generator could keep the furnace running if the transformer failed. The standby was sufficient to avoid damaging the furnace but did not supply enough electricity to continue production.
  82. 82. RPN Reduction %=Ri-Rr/Ri Reliability Centered Maintenance 82
  83. 83. Transformer Fault Tree Transformer Components Bushing Tank Core Winding Tap Changers Isolation Reliability Centered Maintenance 83
  84. 84. Reliability Centered Maintenance 84 Current Control/Prevention methods PM type Component/Item PM Level Visual inspection Oil level Monthly Silica gel Monthly Cooling fans Monthly Temp & gauges Monthly Cleaning External body of the transformer Monthly Tightening Cables Monthly Measurements Voltage Semi annual Ampere Semi annual Sampling Oil Annually
  85. 85. Reliability Centered Maintenance 85 Failure type Frequency per year Oil heated 3 Short circuit 2 Volt regulation function error (tap changers fault) 3 Working condition= 24 hours Failure Log History
  86. 86. Component Name & Function: Bushing, supply high voltage Failure Mode Failure Effect Severity Failure Causes Failure Cause Failure Causes Failure Cause Occurrence Current control detection/pr evention methods Detection RPN Short circuit Equipmentshutdown 4 Fault in insulation material Water penetration or dirt Inelastic gasket Aging 1 Visual inspection and cleaning 6 24 Lack of maintenance 1 6 24 Damage bushing Sabotage stone, crash or Careless handling 1 4 16 Analysis Reliability Centered Maintenance 86 Recommendation Take actions Result S O D RPN Increase inspection & detectability Use infrared camera & ultrasound for high detection ability 4 1 2 8 4 1 2 8
  87. 87. The function of the bushings is to isolate electrical between tank and windings and to connect the windings to the power system outside the transformer Reliability Centered Maintenance 87
  88. 88. Component Name & Function: Tank , enclose oil, protect active parts Failure Mode Failure Effect Severity Failure cause Failure Cause Failure Cause Failure Cause Occurrence Current controls Detection RPM Leakage Equipmentshutdown 4 Tank Damage (Rupture) Material/ method Inelastic gasket or corrosion Aging 1 Visual inspection 5 20 Insufficient maintenance 1 5 20 Mechanica l damage High pressure due to gas generation Arcing 1 None 10 40 Careless handling 1 1 4 Reliability Centered Maintenance 88 Recommendation Take actions Result S O D RPN Increase inspection & detectability Use ultrasound for detection of arcing phenomena 4 1 1 4 4 1 1 4 4 1 1 4
  89. 89. The tank is primarily the container of the oil and a physical protection for the active part of the transformer. It also serves as support structure for accessories and control equipment. The tank has to withstand environmental stresses, such as corrosive atmosphere, high humidity and sun radiation. The tank should be inspected for oil leaks, excessive corrosion, dents, and other signs of rough handling. Reliability Centered Maintenance 89
  90. 90. Component Name & Function: Core, carry magnetic flux Failure Mode Failure Effect Severity Failure Cause Failure Cause Occurrence Current Control Detection RPN Loss of efficiency (reduction of transformer efficiency) Lower voltage, production disturbance 4 Mechanical failure DC magnetization 1 Basic measurements 4 16 Displacement of the core steal during construction (construction fault) 1 4 16 RPN=S x O x D=16 Reliability Centered Maintenance 90 No Recommendation or actions will be taken here.
  91. 91. Reliability Centered Maintenance 91
  92. 92. Failure Mode Failure Effect Severity Failure cause Failure Cause Failure Cause Occurrence Current Controls Detection RPN Short circuit Equipmentshutdown 4 Fault insulation Generation of copper sulfide 1 8 32 Hot spot Low oil quality 1 Oil sampling 1 4 Mechanical damage Movement of transformer Ageing of cellulose 1 None 5 20 Transient overvoltage Short circuit in the net 1 5 20 Connection of transformer 1 5 20 Lightning 1 5 20 Construction fault 1 5 20 Component Name & Function: Winding, carry current Reliability Centered Maintenance 92
  93. 93. Reliability Centered Maintenance 93 Recommendation Take actions Result S O D RPN Increase inspection & detectability Use ultrasound for detection of winding problems 4 1 2 8 4 1 2 8 4 1 2 8 4 1 2 8 4 1 2 8 4 1 2 8
  94. 94. The windings belong to the active part of a transformer, and their function is to carry current. The windings are arranged as cylindrical shells around the core limb, where each strand is wrapped with insulation paper. Copper is today the primary choice as winding material. In addition to dielectric stresses and thermal requirements the windings have to withstand mechanical forces that may cause windings replacement. Such forces can appear during short circuits, lightnings, short circuits in the net or during a movement of the transformer Reliability Centered Maintenance 94
  95. 95. Failure Mode Failure Effect Severity Failure cause Failure Case Failure Cause Failure Case Occurrence Current Controls Detection RPN Oil Equipmentshutdown 4 Short circuit in transformer Particles in the oil Overheated Pump failure, Dirty particles in the oil 2 Visual monitoring of gauges and oil sampling 4 32 Water in the oil Overheated or aging Overheated Oil is not cooled Oil, circulation out of function, or Air/Water cooling is out of function Fan/Pump failure 2 4 32 Component Name & function: Oil, the oil serves as both cooling medium and part of the insulation system Reliability Centered Maintenance 95
  96. 96. Reliability Centered Maintenance 96 Recommendation Take actions Result S O D RPN Increase oil sampling frequency 1. Sample oil every 6 months 2. Increase detectability with infrared camera inspection 4 1 2 8 4 1 2 8
  97. 97. The transformer oil is a highly refined product from mineral crude oil and consists of hydrocarbon composition of which the most common are paraffin, naphthenic, and aromatic oils. The oil serves as both cooling medium and part of the insulation system. The quality of the oil greatly affects the insulation and cooling properties of the transformer. The major causes of oil deterioration are due to moisture and oxygen coupled with heat. Another function of the oil is to impregnate the cellulose and isolate between the different parts in the transformer. Reliability Centered Maintenance 97
  98. 98. Function Failure Mode Failure Effect Severity Failure cause Failure Cause Failure Cause Occurrence Current Controls Detection RPN Regulate volt leveling Tap Changes Change of the voltage output 3 Can’t change voltage level Mechanical damage Wear 2 Voltage measuring 6 36 Component Name & Function : Tap Changers, regulate volt levelling Motorized Taps Reliability Centered Maintenance 98 Recommendation Take actions Result S O D RPN Increase inspection & detectability Use infrared inspection to detect tap changers faults 3 1 2 8
  99. 99. Reliability Centered Maintenance 99
  100. 100. The function of a on-load tap-changer (OLTC) is to regulate the voltage level by adding or subtracting turns from the transformer windings Reliability Centered Maintenance 100
  101. 101. Component Name & Function: Solid Isolation, is cellulose based products such as press board and paper. Its function is to provide dielectric and mechanical isolation to the windings. Failure Mode Failure Effect Severity Failure cause Sources of failure Failure Cause Occurrence Current Controls Detection RPN Can’t supply insulation EquipmentShutdown 4 Mechanical damage Short circuit, Ageing of cellulose 1 None 10 40 Movement of transformer fault in insulation material Ageing of cellulose 1 10 40 Hot spot Low oil quality, or Overload 1 1 4 Generation of copper sulfide 1 10 40 Reliability Centered Maintenance 101
  102. 102. Reliability Centered Maintenance 102 Recommendation Take actions Result S O D RPN Increase inspection & detectability Use ultrasound for detection of winding problems 4 1 2 8 4 1 2 8 4 1 2 8
  103. 103. The solid insulation in a transformer is cellulose based products such as press board and paper. Its function is to provide dielectric and mechanical isolation to the windings. Reliability Centered Maintenance 103
  104. 104. Part/Item RPN Bushing 16 16 16 Tank 20 20 40 4 Core 16 16 Winding 4 4 20 RPN Analysis for Transformer Components Reliability Centered Maintenance 104 Part/Item RPN Winding 20 20 20 Oil 32 32 Tap Changers 36 Solid Insulation 40 40 4 40 Total 492 A cutoff point of RPN 16 can be set because over 50% of the failure modes are above this number.
  105. 105. Total Risk Priority Number= 492 Recommendations 1. Increase the detection probability for the following failures: -Winding insulation -Tap changers -Oil condition -Insulation breakage -Bushing insulation failure -Tank corrosion/leakage 2. Fit more generators to avoid production losses upon transformer failure (we will need more specially if the whole furnaces are working). Corrective Actions (stage 1): 1. Usage of thermal camera to monitor the winding, tap changers, oil temp, insulation, bushing and tank corrosion. 2. Increase visual inspection capability for the tank. Reliability Centered Maintenance 105
  106. 106. Reliability Centered Maintenance 106
  107. 107. Transformer Fins Overheating issue Reliability Centered Maintenance 107
  108. 108. Expected Total Risk Priority Number after applying the corrective actions Corrective Actions (stage 2): Use the Ultrasound detection to detect winding problems & isolation. Expected Total Risk Priority Number after applying the corrective actions (stage 1 &2): Supportive for early detection RPN Reduction %=R initial – R revised/ =492-184/492 =62% R initial Increase inspection reduce the risk of failure Thermal Camera Reliability Centered Maintenance 108
  109. 109. Reliability Centered Maintenance 109 The improvements that yielded success included using ultrasound to detect issues, increasing the frequency of oil sampling and using infrared analysis to detect mechanical damage.
  110. 110. Detect Transformer Problems Electric Discharges: •Arcing •Corona •Tracking Reliability Centered Maintenance 110
  111. 111. Remember FMEA is a Team Work Job! Team Members for FMEA: •Process Engineer •Operators •Quality •Safety •Maintenance •Product engineer •Customer •Supplier Reliability Centered Maintenance 111
  112. 112. Design of FMEA Sheet Reliability Centered Maintenance 112
  113. 113. Reliability Centered Maintenance 113 Each step is a FMEA toward the target
  114. 114. Reliability Centered Maintenance 114 An FMEA process can trigger a number of such actions to improve a product’s service or maintenance processes. They include, but are not limited to:  Increase the detection rate of high-risk failures using a proper technique to monitor conditions.  Increase the inspection rate for a specific component or part.  Modify the routine maintenance program.  Increase the frequency of replacing a specific spare part.  Modify the preventive maintenance schedule.  Change a spare part supplier.  Redesign a specific part in the system – or redesign the whole system.  Use different types of materials or spare parts.
  115. 115. Reliability Centered Maintenance 115 Does FMEA Sound Like a Standalone Tool??
  116. 116. Reliability Centered Maintenance 116 Failure mode and effects analysis can maximize a product’s reliability. But don’t mistake it as a standalone tool. For example, to determine occurrence ratings, FMEAs rely on the failure log history, and the documentation process also is important. Problem-solving techniques like “five whys,” brainstorming, fault-tree analysis and Pareto analysis must be engaged. These techniques will help determine potential failure modes; assign the severity, occurrence and detection rankings; and provide solutions or actions to eliminate those failures. Other Quality Tools and FMEA
  117. 117. Reliability Centered Maintenance 117 Reliability of Firing System
  118. 118. 118Reliability Centered Maintenance
  119. 119. 119 Gauge Reservoir Hose Valve Reliability Centered Maintenance
  120. 120. 120 ID Failure Mode Failure Effect Severity Failure Cause Occurrence Current Control Prevention Current Control Detection Detection RPN Recommendation Action Taken A Cracks Misfire 10 Exposure to excessive heat or cold in shipping 5 Insulated pkg material; temp controlled ship container None 6 300 Use hose that is not temp sensitive Change hose material B Pinholes Low discharge pressure 8 Damage to hose during mfg 8 No sharp objects used in operations None 4 256 Add protection kelvar coating to hose Add puncture resistant cover for hose C Blockages No discharge 10 Foreign object in hose 6 None Incoming inspect; hose air passage test 3 180 None Component ID: 1 Component Name: Hose; delivers extinguishing agent ID Action results Severity Occurrence Detection RPN 1.A 10 2 6 120 1.B 8 5 4 160 Reliability Centered Maintenance
  121. 121. 121 ID Failure Mode Failure Effect Severity Failure Cause Occurrence Current Control Prevention Current Control Detection Detection RPN Recommendation Action Taken A Paint coverage uneven Bare spots rust weakening metal, possible explosion 10 Paint line low on paint 6 Automated inventory mgt system Automated inventory mgt system 2 120 None None B 10 Spray nozzle partially plugged 9 Regular nozzle cleaning procedure None 4 360 Keep nozzle path when not in used in water New procedure instituted Component ID: 2 Component Name: Canister; reservoir for extinguisher agent ID Action results Severity Occurrence Detection RPN 2.B 10 3 4 120 Reliability Centered Maintenance
  122. 122. 122 Failure Mode Failure Effect Severity Failure Cause Occurrence Current Control Prevention Current Control Detection Detection RPN Recommendation Actio n Taken Label not properly applied Label separated from consister, slip out of hand in use 8 Wrong glue or obsolete glue used 3 Glue standard in place None 2 48 None None Operating instructions not readable 7 Excessive humidity 5 Climate control in mfg facility Visual 2 70 None None Component Name: Canister; reservoir for extinguisher agent Reliability Centered Maintenance
  123. 123. 123 ID Failure Mode Failure Effect Severity Failure Cause Occurrence Current Control Prevention Current Control Detection Detection RPN Recommendation Action Taken A Inaccurate reading Overfill if gauge reads low; under fill if gauges reads high 10 Gauge not correctly calibrated 7 None Random calibration inspection 5 350 100% incoming inspection; overflow valve; improve supplier quality Changed to more reliable supplier B Broken crystal Injury to user from cut glass 8 Untempered glass 3 None Incoming glass breakage test 4 96 None None C 8 Sharp blow to crystal 8 None Visual 9 576 Use plastic-break resistance crystal Switche d to plastic crystal Component ID: 3 Component Name: Charge gauge; determine remaining volume of agent ID Action results Severity Occurrence Detection RPN 3.A 8 4 2 64 3.C 3 3 5 45Reliability Centered Maintenance
  124. 124. 124 ID Failure Mode Failure Effect Severity Failure Cause Occurrence Current Control Prevention Current Control Detection Detection RPN Recommendation Action Taken A Safety pin missing Extinguisher engages on its own; slow leakage 10 Pin falls out; too small 2 None Incoming inspection on pen diameter 5 100 None None B 10 Pin not inserted during mfg 9 None Visual 9 810 Issue pin supply in quantities equal to extinguishers Change mfg system to issue material s in kits C Handle jams User unable to discharge extinguisher 10 Handle becomes rusted 5 Rust inhibitor used None 7 350 Switch to rust inhibitor preventing metal Switch to zinc plated metal D 10 Spring in handle too tight 2 None Incoming inspection on springs 4 80 None None Component ID: 4 Component Name: Valve mechanism; releases agent Reliability Centered Maintenance
  125. 125. 125 ID Action results Severity Occurrence Detection RPN 4.B 10 3 3 90 4C 10 1 3 30 Reliability Centered Maintenance
  126. 126. Part/Item RPN Hose 300 256 180 Gauge 120 360 48 70 Canister 350 96 576 Valve 100 810 RPN Analysis for Transformer Components 126 Part/Item RPN Valve 350 80 Total 3796 A cutoff point of RPN 200 can be set because over 50% of the failure modes are above this number. Reliability Centered Maintenance
  127. 127. 127 Create a Pareto chart of failure modes so that it would be easy to distinguish visually between items. The team decided it would work on any item that had an RPN of 200 or higher. That was the cutoff point because it encompassed over half of all of the potential failure modes. Time allowed for actions to be implemented: 6 weeks Total RPN reduction= (3796-1323)/ 3796= 65% Reliability Centered Maintenance
  128. 128. Reliability Centered Maintenance 128 Eng. Mohammed Hamed Ahmed Soliman The American University in Cairo Email: mhamed206@yahoo.com m.h.ahmed@ess.aucegypt.edu Tel: +201001309903 https://eg.linkedin.com/in/mohammedhamed References: Raymond J. Mikulak, Robin McDermott. (2008). The Basics of FMEA. Productivity Press; 2 edition Robert T. Amsden and Davida M. Amsdenand. (1998). SPC Simpliefied: Practical steps to quality. Productivity Press; 2 edition KTH Electrical Engineering

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