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Introduction to Reliability Centered Maintenance

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Introduces Reliability Centered Maintenance, strategies employed, formulation of effective maintenance plan, reduction of consequences of failures and failure rate.

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Introduction to Reliability Centered Maintenance

  1. 1. © RMCPL All rights reserved
  2. 2. © RMCPL All rights reserved Make Life Easy & Innovative Thru RCM
  3. 3. Vision  To improve reliability of critical plant and machinery to improve upon Productivity, Performance and Profitability.
  4. 4. Mission  Formulate a Reliability Centered Maintenance plan with clear strategy  Would be able to have a firm grasp on application of CBM techniques in improving reliability of a plant.  Would be able to carry out deep analysis of failure modes in order to improve upon the inherent reliability of a plant
  5. 5. MAINTENANCE RELIABILITY ENERGY EFFICIENCY COST & SAFETY ENVIRONMENT WORK LIFE © RMCPL All rights reserved
  6. 6. RCM – some definitions  Maintenance: Ensuring that physical assets continue to do what their users want them to do.  RCM: a process used to determine what must be done to ensure that any physical asset continues to do what its users want it to do in its present operating context.  RCM helps people determine the best maintenance tasks in a cost effective manner for managing the functions of physical assets – and for managing the consequences of functional failures.  RCM does not challenge the design of the equipment or system
  7. 7. Why RCM?  IN ORDER TO SUCCESSFULLY COMPETE TODAY, PLANT AVAILABILITY AND RELIABILITY MUST BE MAINTAINED AT DESIRED LEVELS WHILE OPERATING COSTS MUST BE KEPT AS LOW AS REASONABLY ACHIEVABLE.  A KEY ELEMENT IN THIS COST REDUCTION IS CONTROLLING MAINTENANCE PRACTICES.
  8. 8. RCM - features  Structured - Logical – nothing done without a reason  Reduces intrusiveness and improves flexibility of maintenance teams  Auditable -- Quantifiable results and benefits  Induces higher skills (cognitive and physical) of technicians  Living document
  9. 9. RCM – Benefits  Choosing the appropriate maintenance strategies/tasks  Formulating a structured maintenance plan and schedule  Avoid/minimize consequence of a failure  Reduction in maintenance tasks (25% to 50%)  Reduction in number of failures (15% to 25%)  Reduction in costs (25% to 50%)  Improved quality of maintenance actions  Maximizing Reliability, Availability, Safety  Optimum use of maintenance resources
  10. 10. Main Benefits 1. PHASE-OUT COSTLY INTRUSIVE INSPECTIONS 2. DEVELOP CBM PROGRAM TO CONDITIONALLY DIRECT MAINTENANCE ACTIVITIES. 3. DISCOVER “BAD ACTORS” 4. IDENTIFYING MORE COST-EFFECTIVE TASKS 5. REFINE PRIORITIZATION Of Maintenance
  11. 11. Maintenance Strategies & Evolution  On-Failure maintenance (OFM)  Time Based Maintenance (TBM)  Condition Based Maintenance (CBM)  Detective Maintenance  Design Out Maintenance (DOM)  Opportunity Maintenance (OM)
  12. 12. On-Failure Maintenance  Advantages:  Can be effective where consequence of a failure is zero  Disadvantages:  Affects production (undesired downtime)  Affects quality  Large stand-by crew  Large stock of spare parts
  13. 13. Time Based Maintenance  Advantages:  Can be applied to components purely subjected to time based wear (2%)  And consequences of a failure is relatively low  Disadvantages:  Scheduled overhaul; however intensive; of complex equipment has little or no effect on in-service reliability  Increase in cost  Lack of time  Large stock of spare parts  Large crew needed
  14. 14. Condition Based Maintenance  Advantages:  Maintenance can be done as needed  Can be applied to random failures (minimum 68%)  Applied where consequences of a failure ranges from Low to high  Detects incipient and hidden failures in time  Prevents secondary damage  Maintenance can be planned in advance to fit production windows  Resources can be optimized as per need and operating context  Can be operator driven or system driven or IOT driven  Disadvantages:  High skill needed to implement and run a CBM system  Multiple failures can happen at the same time stressing the maintenance system
  15. 15. © RMCPL All rights reserved Pump Vibration Measurement Thermography of switch Yard Wear debris analysis (External) Non contact temperature measurement Condition Based Maintenance
  16. 16. © RMCPL All rights reserved What is Trend Monitoring? 60 Life Units 50 40 30 20 10 0 CM depends on the trending of parameters which are indicators of the condition of key equipment failure modes
  17. 17. © RMCPL All rights reserved Warning Alarm Detection of Defects Cause finding through correlation
  18. 18. © RMCPL All rights reserved
  19. 19. Design Out Maintenance (DOM)  Advantages:  Can be applied to prevent repeat failures  Minimizes or eliminates failure rate  Generally applied where consequences of a failure is high  Maintenance can be minimized  Minimum resources needed to maintain assets  Disadvantages:  High skill needed  Time
  20. 20. EXISTING STRATEGIES © Dibyendu De#POWEROFSEE TBM Preventing age related failures (2% to 5%) RCM prevents consequences of failures OFM no control on failures CBM Detects random failures(>68%)
  21. 21. Basic Steps to RCM
  22. 22. © RMCPL All rights reserved On-Failure Fix it when it fails Condition Based Maintain based upon known condition Maintenance PlanFixed Time Maintain based upon calendar or running time Design Out Identify & design out root cause of failure
  23. 23. 7 Questions…. 1. WHAT ARE THE FUNCTIONS AND RELATED PERFORMANCE STANDARDS OF THE ASSET IN ITS CURRENT OPERATING CONTEXT? 2. WHAT ARE THE POSSIBLE WAYS IN WHICH THE ASSET MAY FAIL TO PERFORM ITS REQUIRED FUNCTIONS? 3. WHAT ARE THE CAUSES OF EACH FUNCTIONAL FAILURE OR FAILURE MODE? 4. WHAT ARE THE EVENTS THAT FOLLOW EACH FAILURE?
  24. 24. 7 Questions… 5. WHAT IS THE SIGNIFICANCE OF EACH FAILURE? 6. WHAT MEASURES CAN BE TAKEN TO PREVENT FAILURE? 7. WHAT MIGHT BE THE CORRECTIVE MEASURES THAT MAY BE TAKEN IF THERE IS NO APPROPRIATE PREVENTIVE STEP?
  25. 25. The RCM Process Application  DURING EQUIPMENT DESIGN AND DEVELOPMENT PHASE, WHEN IT IS USED TO DEVELOP MAINTENANCE PLAN.  DURING EQUIPMENT/PRODUCT OPERATION AND DEPLOYMENT, THESE PLANS ARE THEN MODIFIED BASED ON FIELD EXPERIENCE.
  26. 26. 2 criteria  PARTS THAT ARE NOT CRITICAL TO SAFETY –preventive maintenance tasks should be chosen that will decrease the ownership life ownership life cycle cost (LCC).  PARTS THAT ARE CRITICAL TO SAFETY – maintenance tasks should be chosen that will that will help prevent reliability or safety from safety from drooping to an unacceptable level, unacceptable level, or will help reduce the the ownership life cycle cost (LCC).
  27. 27. Heart of the thing  INCIPIENT & HIDDEN FAILURES ARE DETECTED AND CORRECTED – APPLICATION OF CBM TECHNIQUES  PROBABILITY OF FAILURE IS REDUCED – APPLICATION OF DESIGN OUT MAINTENANCE (DOM)  SYSTEMIC ROOT CAUSE FAILURE ANALYSIS (SRCFA)  REDUCE OWNERSHIP OF LIFE CYCLE COST
  28. 28. Analysis & design of systems  FOCUS ON CRITICAL EQUIPMENT WITH DOCUMENTED FAILURE MODES. (Maintenance Records)  STRATEGY EMPHASIZING CONDITION-BASED TASKS.  IDENTIFYING ACTIONS THAT HELP PRECLUDE COSTLY UNPLANNED CORRECTIVE MAINTENANCE.  IDENTIFYING AND REMOVING UNNECESSARY ROUTINE PM TASKS. (Review of Equipment Maintenance - REM)
  29. 29. The 7 step process STEP 1: DETERMINE EQUIPMENT/PARTS WITH HIGHEST MAINTENANCE PRIORITY. OBTAIN APPROPRIATE FAILURE DATA, WHICH MAY BE OBTAINED FROM – A) A) EQUIPMENT HISTORY B) WORK ORDERS STEP 2: DETERMINE CONTEXTUAL FAILURE MODES STEP 3: PERFORM SYSTEMIC ROOT CAUSE ANALYSIS – FTA, FTA, FMECA, SRCFA TECHNIQUES
  30. 30. Reliability Centered Maintenance © Dibyendu De#POWEROFSEE review • MULL• EXCHAN GE • ENGAGE• NOTICE CHANGES ? PATTERN S? INTERACTI ONS? MINIMA L CHANG ES
  31. 31. © RMCPL All rights reserved 2 3 41 0.99 x 0.99 x 0.99 x 0.99 = 0.96 ≈ 96% Process Reliability
  32. 32. © RMCPL All rights reserved Equipment diagram Pump Gear Box Motor B CA
  33. 33. Determining Criticality Period selected = 2 yr/1yr/6m (Tp) # Equipment Frequency # (F) Downtime (total) Hrs (DT) F x DT Rank 1 Xxxx 20 50 1000 2 2 Yyyy 5 500 2500 1 3 Zzzz 10 40 400 3 From this we also obtain: MTBF = Tp/F MTTR = DT/F Steady State Reliability R = MTBF/(MTBF + MTTR) and other maintenance parameters Risk
  34. 34. Critical equipment for Power plant 1. MAIN STEAM AND WATER 2. FUEL HANDLING 3. CIRCULATING WATER 4. ASH HANDLING 5. SOOTBLOWING
  35. 35. Critical equipment for Power plant…. 6. BOILER GAS AND AIR 7. FEEDWATER HEATER DRAINS/EXTRACTION STEAM 8. COAL HANDLING 9. FEEDWATER 10. CONDENSATE
  36. 36. © RMCPL All rights reserved Failure Characteristics Failure Probability Graph Condition Monitoring Mean Time Before Failure Strategy in order of preference Analysis of Maintenance Records permits an effective strategy to be chosen
  37. 37. The 7 step process STEP 1: DETERMINE EQUIPMENT/PARTS WITH HIGHEST MAINTENANCE PRIORITY. OBTAIN APPROPRIATE FAILURE DATA, WHICH MAY BE OBTAINED FROM – A) A) EQUIPMENT HISTORY B) WORK ORDERS STEP 2: DETERMINE CONTEXTUAL FAILURE MODES STEP 3: PERFORM SYSTEMIC ROOT CAUSE ANALYSIS – FTA, FTA, FMECA, SRCFA TECHNIQUES
  38. 38. Critical Equipment: Vertical Roller Coal Mill Sub-assembly: Main Gear Box Performance Standard: To provide constant torque to Mill table Failure Mode MTBF Failure Pattern Warning Effect Root Cause Consequence Risk Rating Bearing cracked (anti-friction) 2 yrs Random Increased noise Bush Wear of output shaft -> Lateral shift of input shaft Full Load loss 1
  39. 39. De Diagram: S^S -> E -> Failure Mode
  40. 40. 7 step process….. STEP 5: CLASSIFY MAINTENANCE REQUIREMENT – CBM, DOM, TBM, OFM, LABOUR, SPARES, INSTRUMENTS, SOFTWARE, ETC. STEP 6: IMPLEMENT RCM DECISIONS. CHECK EFFECTIVENESS.
  41. 41. Critical Equipment: Vertical Roller Coal Mill Sub-assembly: Main Gear Box Performance Standard: To provide constant torque to Mill table Maintenance Action Strategy Frequency Responsibility Remarks 1. Measure displacement (H) on Input shaft 2. Change Bush material 3. Change lubricant specification 4. Drill hole on bearing cover CBM DOM DOM DOM 1M One Time One Time One Time MID Engineering Engineering Engineering Use low frequency sensor Within 3 m Within 3 m; Servomesh EE 320 To let out debris; else enter bearing
  42. 42. © RMCPL All rights reserved On-Failure Fix it when it fails Condition Based Maintain based upon known condition Maintenance PlanFixed Time Maintain based upon calendar or running time Design Out Identify & design out root cause of failure
  43. 43. RCM Maintenance Plan Distribution 2 68 5 30 Plan OFM CBM TBM DOM DOM TBM CBM
  44. 44. © RMCPL All rights reserved Life Lost Additional Life Time N Risk Just Restore (Plan) Restore with Improvements (Innovate) Threshold
  45. 45. TPM:PEOPLE CBM:STEM RCM:RISK RI:cREATIvITY 1/10 1/20 1/40 1/100 © RMCPL All rights reserved
  46. 46. Failure Modes: Verb + Noun # Noun Verb 1 Bearing Seized 2 Bearing Worn 3 Shaft Cracked 4 Seal Worn 5 Motor Burnt 6 Contact Short-circuited 7 Coil Burnt 8 Gear Worn 9 Hinge Bent 10 Packing Leaked # Noun Verb 11 Switch Open 12 Circuit Open 13 Valve Sticking 14 Lubricant Foaming 15 Lubricant Heated 16 Tubes Clogged 17 Rotor Bowed 18 Filter Jammed 19 Oil Contaminated 20 Contact Pitted
  47. 47. MTBF  Mean Time Between Failures = Time period of observation/#of failures Usually a two years of observation period is ideal. With lack of information a 6 months period is just enough With no information Dynamic analysis is employed to ascertain failure modes.
  48. 48. © RMCPL All rights reserved Failure Rate Early Random Failure Wear Out Time Typical “Bathtub” Curve 30%
  49. 49. © RMCPL All rights reserved 70% 25% 05% 2 Pyramids (Nature of Problems) Big Problem Medium Problem Small Problem Possible > 2hr < 2 hr < 30m 70% 25% 05% Wear Early Random
  50. 50. Failure Patterns – contd..  Random (68 to 80% cases)  CBM is the default  Time based (2 to 5% cases)  TBM is the default  Early (> 10%)  DOM is the default  Hidden (5%)  CBM/DOM is the default  Complex  Combination of strategies needed
  51. 51. Warning Effect (e.g.)  Vibration  Noise  Loss of performance  Quality  Overheating  Leakage  Corrosion  Etc. Actions are taken by considering both effect and causes
  52. 52. Failure Cause(s): FRECTLS (e.g.) # Basic Cause Manifestations 1 F Unbalance Force/ Misalignment Inertia Looseness Acceleration Decelration Impact Torsion Bending/Bow Crack/Open Fatigue (low) Fatigue (high) Flow Flow turbulence Foundation # Basic Cause Manifestations 2 R Selective Transfer Reactive Chemical reaction Material Moisture Restrictions 3 E Dust Environment Humidity/Dryness Ambient Temp EM interference Heat transfer Vibration Nox/Ozone Human Pressure
  53. 53. Failure Cause(s): FRECTLS (e.g.) # Basic Cause Manifestations 4 C Small Changes Chaos Periodic attractor & Resonance Complexity Point attractor Oscillating Big changes Non-Equilibrium Non-Linearity Feedback loop 5 T High Temperature Low Transition # Basic Cause Manifestations Thermal shocks Variations Entropy Heat band Radiation Convection Conduction 6 L Incompatible Lubrication Additive loss & Viscosity Wear Moisture Temperature
  54. 54. Failure Cause(s): FRECTLS (e.g.) # Basic Cause Manifestations L Wear Lubrication Adhesive & Abrasive (2 body) Wear Abrasive (3 body) (contd) Erosion Catastrophic Pitting Spalling Flaking Brinelling Fluting Fretting Corrosion (8) Stress Corrosion # Basic Cause Manifestations 7 S Structure/Soil Structure Speed Speeds Surface rough Surfaces Sync Space/Shape Symmetry/Asym Softness/Sticky Surface interfaces Shocks/Impact Sound/Noise Substance Shorting Separation System design
  55. 55. Consequences and Ranking Priority Reliability/Capability Efficiency Environment Safety Employee Worklife 1 Full Load loss Non-compliance Asset required to protect life/property Protect employee life 2 Major derating 40% or more Imminent violation 3 Significant derating 20% or more Heat rate effect significant 4 0% derating but possible generation loss due to extended asset failure Prevents effective management Redundant safety system Employee Safe work environment 5 Possible loss of generation due to to failure of redundant equipment Heat rate effect moderate Supports training needs 6 Loss of assets causes loss of auto function to multiple equipment or or system Detracts from improvement goals Protects equipment from damage 7 Loss of asset causes significant operational inconvenience Heat rate effect minimal Provides employee comfort 8 Loss of asset precludes normal system or equipment operation 9 No effect No effect No effect No effect No effect
  56. 56. Maintenance Tasks are guided by  Nature of Failure Mode, Pattern, Warning Effect, Cause(s) and Consequence  Frequency of a CBM task = MTBF/5  Task takes care to avoid the consequences  Task takes care to detect incipient defects  Task takes care to increase the MTBF  Task takes care to reduce the MTTR
  57. 57. © RMCPL All rights reserved Equipment Causes of Failure Techniques Comments Fan Out of balance Misalignment Bearing damage Aerodynamic forces Belt problems Overall acceleration Spike energy measurement Overall vibration Vibration analysis Flow measurement Motor current measurement Simple application using windowed spectra to trend deterioration in specific faults. Equipment performance is monitored by measuring process parameters Application of Monitoring Techniques
  58. 58. Basic Steps to RCM
  59. 59. 7 step process…. STEP 7: BASE SUSTAINING ENGINEERING ON REAL-LIFE LIFE EXPERIENCE DATA – LIVING RCM
  60. 60. © RMCPL All rights reserved 2% Unpredictable 30% Plan 68% Improvements Make Life easy & Innovative
  61. 61. © RMCPL All rights reserved # Audit Parameters Previous After 1year After 2years 1 No. of breakdowns per year 57 19 3 2 % of breakdown hours 25 12 5
  62. 62. Reliability Centered Maintenance © Dibyendu De#POWEROFSEE # Audit Parameters Previous After 1 Year After 2 Years 1 No. of Breakdowns /Year 57 19 3 2 % of Breakdown Hours 25 12 5 effects of ON CEMENT PLANT 57 19 3 25 12 5 0 10 20 30 40 50 60 Previous After 1 Year After 2 Years Effect of ACM No of BreakDowns/Year % of BreakDown Hours
  63. 63. © RMCPL All rights reserved No. of Breakdowns (Avg/Month) 1st Year 2nd Year 3rd Year 4th Year 30 20 10 0 Number
  64. 64. © RMCPL All rights reserved 1 2 3 4 5 6 7 8 9 10 11 12 25 20 15 40 30 20 10 0 Reliability vs. Cost
  65. 65. RCM – broad steps - Implementation  Equipment survey to establish time and costs  Prioritise and plan the project  Set up Study Team  Carry out study  Produce reports and schedules  Monitor results, failure modes, schedules and tune the program
  66. 66. RCM – Outcome of the Study  Facilitated sessions between –  RCM Facilitator  Stakeholders of an area/equipment  Study Group produces the reports in form of a structured plan  Reports are turned into actionable maintenance schedules and recommendations.  Produce reports and schedules  Monitor results, failure modes, schedules and tune the program
  67. 67. summary  CONCENTRATE MAINTENANCE RESOURCES WHERE THEY WILL DO THE MOST GOOD.  ELIMINATE UNNECESSARY AND INEFFECTIVE MAINTENANCE.  DEVISE THE SIMPLEST AND MOST COST-EFFECTIVE MEANS OF MAINTAINING EQUIPMENT, OR TESTING FOR DEGRADATION  FOCUS PM TASKS ON PREDICTIVE OR CONDITION MONITORING ACTIVITIES WHERE APPLICABLE. DEVELOP A DOCUMENTED BASIS AND HISTORY FOR THE MAINTENANCE PROGRAM.  MAXIMIZE PLANT EMPLOYEE AND ANALYST EXPERIENCE WHEN DETERMINING EQUIPMENT TASKS WITH
  68. 68. Reilability Centered Maintenance © Dibyendu De#POWEROFSEE ingredients PEOPLE LEADERS
  69. 69. © RMCPL All rights reserved Once done the company gains permanent on- going benefits. Prof. Tim Henry, Manchester University, U.K
  70. 70. © RMCPL All rights reserved Contact Dibyendu De dde337@gmail.com +91 7044627404 / 9836466678

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