J-5.pdf

RELIABILITY CENTERED MAINTENANCE

MANUAL

APRIL 2002

DRAFT

April 2002 DOS Reliability Centered Maintenance Manual

Table of Contents

Preface .............................................................................................................................................. i

Section I Introduction ................................................................................................................. I 1 A. Definition .................................................................................................................. I 1 B. Types of RCM .......................................................................................................... I 2

1. Classical/Rigorous RCM ..................................................................................... I 2

2. Abbreviated/Intuitive/Streamlined RCM ............................................................ I 3

C. Background .............................................................................................................. I 3 D. Purpose of this Manual ............................................................................................. I 5 E. Applicability ............................................................................................................. I 5 F. Use of this Manual ................................................................................................... I 6

Section II Reliability Centered Maintenance Approach ............................................................ II 1 A. Philosophy ............................................................................................................... II 1 B. RCM Analysis ......................................................................................................... II 1 C. RCM Principles ....................................................................................................... II 3 D. Failure ...................................................................................................................... II 4

1. System and System Boundary ............................................................................ II 4

2. Function and Functional Failure ......................................................................... II 5

3. Failure Modes ..................................................................................................... II 5

4. Reliability ........................................................................................................... II 5

5. Failure Characteristics ........................................................................................ II 6

6. Preventing Failure .............................................................................................. II 8

E. Failure Modes and Effects Analysis ........................................................................ II 9

1. Criticality and Probability of Occurrence ........................................................ II 11

2. Cause of Failure ................................................................................................ II 12

F. Reliability Centered Maintenance Goals ............................................................... II 13 G. Program Benefits ................................................................................................... II 14

1. Safety and Security ........................................................................................... II 15

2. Cost ................................................................................................................... II 15

3. Reliability ......................................................................................................... II 15

4. Scheduling ........................................................................................................ II 15

5. Efficiency/Productivity .................................................................................... II 15

H. Impact of RCM on the Facilities Life Cycle ......................................................... II 16 I Measuring RCM Program Effectiveness (Metrics) ............................................... II 17

1. Measuring the Program .................................................................................... II 17

2. Purpose of Metrics ............................................................................................ II 18

3. Sample Metrics ................................................................................................. II 19

4. Trending Indicators .......................................................................................... II 20

5. Recommended Metrics ..................................................................................... II 21

6. Metric Selection ............................................................................................... II 23

7. Benchmark Selection ....................................................................................... II 24

8. Utilization of Metrics ....................................................................................... II 24

Section III RCM Program Components .................................................................................. III 1 A. Reactive Maintenance ........................................................................................... III 1

1. RTF Examples ................................................................................................ III 2

2. Reactive Maintenance Criteria ........................................................................ III 2

B. Preventive Maintenance (PM) ............................................................................... III 2

1. Preventive Maintenance Criteria ..................................................................... III 3

2. Determining PM Task and Monitoring Periodicity ........................................ III 3

C. Condition Monitoring ............................................................................................ III 5 D. Proactive Maintenance .......................................................................................... III 5

1. Specifications for New/Rebuilt Equipment .................................................... III 6

2. Precision Rebuild and Installation .................................................................. III 7

3. Failed-Part Analysis ........................................................................................ III 8

4. Root-Cause Failure Analysis (RCFA) ............................................................. III 9

5. Reliability Engineering ................................................................................. III 10

6. Rebuild Certification/Verification ................................................................ III 10

7. Age Exploration ............................................................................................ III 10

8. Recurrence Control ....................................................................................... III 11

E. Facilities Condition Assessment ......................................................................... III 14

Section IV Condition Monitoring Technologies ..................................................................... IV 1 A. Introduction ........................................................................................................... IV 1

1. Alerts and Alarms ........................................................................................... IV 1 B. Vibration Monitoring and Analysis ....................................................................... IV 3

1. Applications and Techniques .......................................................................... IV 3

2. Limitations ...................................................................................................... IV 6

3. Logistics .......................................................................................................... IV 6

C. Infrared Thermography ......................................................................................... IV 7

1. Applications .................................................................................................... IV 8

2. Limitations ...................................................................................................... IV 8

3. Logistics .......................................................................................................... IV 8

D. Passive (Airborne) Ultrasonics .............................................................................. IV 9

1. Applications and Procedures ......................................................................... IV 10

2. Limitations .................................................................................................... IV 12

3. Logistics ........................................................................................................ IV 12

E. Lubricant and Wear Particle Analysis ................................................................. IV 13

1. Purpose .......................................................................................................... IV 13

2. Lubrication Analysis ..................................................................................... IV 14

3. Standard Analytical Tests ............................................................................. IV 14

4. Special Tests ................................................................................................. IV 17

5. Application .................................................................................................... IV 19

6. Sampling ....................................................................................................... IV 21

F. Water Testing and Treatment ............................................................................. IV–21

1. Purpose ......................................................................................................... IV– 21

2. Corrosion...................................................................................................... IV– 22

3. Scale .......................................................................................................... IV– 22

4. Biological Growth ........................................................................................ IV– 23

5. Testing.......................................................................................................... IV– 23

6. Operating Parameters ................................................................................... IV– 24

G. Electrical Condition Monitoring ......................................................................... IV 25

1. Techniques .................................................................................................... IV 25

2. Additional Techniques and Troubleshooting ................................................ IV 33

3. Applications .................................................................................................. IV 34

4. Logistics ........................................................................................................ IV 35

H. Non-Destructive Testing ..................................................................................... IV 36

1. Techniques ...................................................................................................... IV 36

2. Location and Intervals .................................................................................... IV 42

3. Applications .................................................................................................... IV 44

4. Limitations ...................................................................................................... IV 46

I. Data Correlation .................................................................................................. IV 48

Section V Condition Monitoring Criteria ................................................................................. V 1 A. Baselines ................................................................................................................. V 1 B. Criteria by Conditioning Monitoring Technology ................................................. V 1

1. Vibration Monitoring ........................................................................................ V 1

2. Lubricant and Wear Particle Analysis ............................................................... V 5

3. Thermography ................................................................................................... V 7

4. Airborne Ultrasonics ......................................................................................... V 8

5. Motor Circuit Analysis .................................................................................... V 11

6. Motor Current Signature Analysis (MCSA) ................................................... V 12

7. Insulation Resistance ....................................................................................... V 13

8. Surge Testing ................................................................................................... V 14

9. Start-Up Tests .................................................................................................. V 14

Section VI RCM Requirements During Facilities Acquisition ............................................... VI 1 A. Planning ................................................................................................................. VI 1 B. Design .................................................................................................................... VI 1

1. Maintainability and Ease of Monitoring .......................................................... VI 1

2. Technology Review .......................................................................................... VI 2

C. Construction .......................................................................................................... VI 3 D. Maintenance and Operations (M&O) .................................................................... VI 4

Section VII Building Commissioning .................................................................................... VII–1 A. Building Commissioning Overview .................................................................... VII–1

1. Use of an Independent Commissioning Authority ......................................... VII–2

2. Types of Commissioning ............................................................................... VII–3

3. The Commissioning Team – The Players ...................................................... VII–4

4. Components and Phases ................................................................................. VII–5 B. The Commissioning Process ............................................................................... VII–6

1. Developing the Design Intent and Basis of Design ....................................... VII–6

2. The Commissioning Plan ............................................................................... VII–8

3. Designing to Design Intent ............................................................................ VII–9

4. Matching Equipment and Space Size to Needs and Optimal Performance ... VII–9

5. Maintainability and Supportability .............................................................. VII–10

6. Design Deficiency Detection ....................................................................... VII–12

7. Specification Requirements ......................................................................... VII–12

8. Quality Construction Checks ....................................................................... VII–13

9. TAB Evaluation ........................................................................................... VII–14

10. EMS Calibration ........................................................................................ VII–14

11. Prefunctional, Condition Acceptance, and Functional Performance Testing......................................................................................................... VII–15

12. Training ....................................................................................................... VII–18

13. Documentation ............................................................................................ VII–19

14. Continued Quality and Reliability .............................................................. VII–22

15. Warranty Enforcement ................................................................................ VII–22

Section VIII – RCM Contract Clauses................................................................................... VIII 1 A. General Contract Clauses ................................................................................... VIII 1

1. Measurements and Measurement Data .......................................................... VIII–2

2. Bearing Information ...................................................................................... VIII 2

3. Gearbox Information ..................................................................................... VIII 2

4. Pumps .......................................................................................................... VIII 3

5. Centrifugal Compressors .............................................................................. VIII 3

6. Fans .......................................................................................................... VIII 3

7. Vibration Monitoring .................................................................................... VIII 4

8. Vibration Monitoring Locations ................................................................. VIII 10

9. Lubricant and Wear Particle Analysis ........................................................ VIII 12

10. Thermography ........................................................................................... VIII 17

11. Airborne Ultrasonics ................................................................................ VIII 18

12. Pulse Echo Ultrasonics ............................................................................. VIII 18

13. Motor Circuit Analysis (Complex Phase Impedance) .............................. VIII 18

14. Motor Current Spectrum Analysis ........................................................... VIII 19

15. Insulation Resistance ................................................................................ VIII 19

16. Surge Testing ............................................................................................ VIII 19

17. Start-Up Tests ........................................................................................... VIII 19

18. Maintainability and Ease of Monitoring .................................................. VIII 19

19. Equipment Pads ........................................................................................ VIII 20

20. Leveling of Installed Equipment .............................................................. VIII 20

B. Architectural and Engineering (A&E) Contracts ............................................. VIII 20 C. Construction Contracts ..................................................................................... VIII 20 D. Equipment Procurement Contracts ................................................................... VIII 22

E. Maintenance and Operations (M&O) Contracts .............................................. VIII 23

Section IX Checklists for RCM Quality Assurance ................................................................ IX 1 A. Planning ................................................................................................................. IX 1 B. Design .................................................................................................................... IX 1 C. Construction .......................................................................................................... IX 2 D. Equipment Procurement ........................................................................................ IX 3 E. Maintenance and Operations ................................................................................. IX 3

Section X RCM During Facilities Operation ............................................................................ X 1 A. RCM Program Data ................................................................................................ X 1 B. Maintenance Feedback ........................................................................................... X 1 C. Maintenance and Operations (M&O) Considerations ............................................ X 2

1. Labor Force ....................................................................................................... X 2

2. System Experts .................................................................................................. X 2

3. Training ............................................................................................................. X 3

4. Equipment ......................................................................................................... X 4

5. Maintenance History ......................................................................................... X 4

6. Procedural Documentation ................................................................................ X 5

Appendices

Appendix A Glossary Appendix B Abbreviations/Acronyms Appendix C Technical Data Appendix D Bibliography Appendix E Sources of CdM Equipment, Services, and Training Appendix F Vibration Criteria Appendix G CdM Technologies Correlation Relationships Appendix H Alignment Standard Appendix I Balance Standard Appendix J AC Motor Repair Specification Appendix K Maintenance Procedures

List of Tables

2 1 Criticality/Severity Categories ...................................................................................... II 11 2 2 Probability of Occurrence Categories ........................................................................... II 12 2 3 Chilled Water System Analysis .................................................................................... II 12 2 4 Electric Motor Component Analysis ............................................................................ II 13 2 5 Cause of Motor Bearing Failure ................................................................................... II 14 2 6 RCM Facility Life-Cycle Implications ......................................................................... II 16 3 1 Maintenance Priority Levels ......................................................................................... III 1

3 2 Reactive Maintenance Priorities ................................................................................... III 2 3 3 Limitations on Rolling Bearing Misalignment (Harris, 1984) ...................................... III 8 4 1 Estimated Steam Loss ................................................................................................. IV 11 4-2 Recommended Maximum Inspection Intervals (API 570) ......................................... IV- 42 5 1 Actions Required Based on Temperature Rise Under Load .......................................... V 7 5 2 Temperature Limits for Selected Components .............................................................. V 9 7 1 Sample Functional Performance Test Form .............................................................. VII–23 8-1 Motor Balance Specifications .................................................................................... VIII 7 8 2 Motor Vibration Criteria ............................................................................................ VIII 7 8 3 Pump Vibration Limits .............................................................................................. VIII 8 8 4 Belt-Driven Fan Vibration Limits .............................................................................. VIII 9 8 5 ISO 3945 Vibration Severity Table. .......................................................................... VIII 9 8 6 Vibration Acceptance Classes.................................................................................. VIII 10 8 7 Machine Classifications ........................................................................................... VIII 10 8 8 Lubricant Tests......................................................................................................... VIII 14 8 9 Sperry Vickers Table of Suggested Acceptable Contamination Levels for Various Hydraulic Systems...................................................................................... VIII 15 8 10 Typical Properties of Transformer Oils ................................................................... VIII 16 8 11 RCM Clauses for A&E Contracts ............................................................................ VIII 20 8 12 RCM Clauses for Construction Contracts................................................................ VIII 21 8 13 RCM Clauses for Equipment Procurement Contracts ............................................. VIII 22 8 14 RCM Clauses for M&O Contracts ........................................................................... VIII 24 9 1 RCM Quality Assurance Planning Considerations ....................................................... IX 1 9 2 RCM Quality Assurance Design Considerations .......................................................... IX 2 9 3 RCM Quality Assurance Construction Considerations ................................................ IX 2 9 4 RCM Quality Assurance Equipment Procurement Considerations .............................. IX 3 9 5 RCM Quality Assurance Maintenance and Operations Considerations ....................... IX 4 10 1 Maintenance Training .................................................................................................... X 4

List of Figures

1 1 Components of an RCM Program.................................................................................... I 1 1 2 Bearing Life Scatter ......................................................................................................... I 4 2 1 Reliability Centered Maintenance (RCM) Logic Tree ................................................... II 2 2 2 Conditional Probability of Failure Curves ...................................................................... II 6 2 3 Preventing Failure ........................................................................................................... II 8 2 4 Sample FMEA Worksheet (Partial) for West African Electrical Distribution System ........................................................................................................................... II 10 2 5 Stages of Life-Cycle Cost Commitment ....................................................................... II 17 3 1 Effects of Misalignment on Roller Bearings ................................................................ III 9 3 2 Failure Analysis Form................................................................................................. III 12 3 3 Office Assessment Form ............................................................................................. III 16

4 1 CdM Applications ......................................................................................................... IV 2 4 2 Sound Disc Diagram ..................................................................................................... IV 5 4 3 Lubrication Analysis Chart ......................................................................................... IV 15 4 4 Power Factor Current/Voltage Relationship ............................................................... IV 26 4 5 NDT Technique Selection Process ............................................................................. IV 37 4 6 Shielded Radiography Enclosure ................................................................................ IV 38 4 7 Magnetic Particle Testing ........................................................................................... IV 40 4 8 Inspection Program Development ............................................................................... IV 45 4 9 Sample System ............................................................................................................ IV 49 5 1 Pump Vibration, Before and After Balancing ................................................................ V 4 5 2 Fan Vibration, Before and After Balancing ................................................................... V 5 5 3 Wear Particle Size and Equipment Condition ............................................................... V 6 5 4 Infrared Image of Distribution Connector ................................................................... V 10 5 5 Infrared Image of a Bad Electrical Connection ........................................................... V 10 7 1 Functional Performance Test Process ........................................................................ VII–17 8–1 Transducer Response ................................................................................................. VIII 4 10 1 Design Improvements through Maintenance Feedback ................................................. X 3

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PREFACE

With a few exceptions, preventive maintenance has been considered the most advanced and effective maintenance technique available for use by industrial and facility maintenance organizations. A Preventive Maintenance (PM) program is based on the following:

One of the underlying assumptions of maintenance theory has always been that there is a fundamental cause-and-effect relationship between scheduled maintenance and operating reliability. This assumption was based on the intuitive belief that because mechanical parts wear out, the reliability of any equipment [is] directly related to operating age. It therefore followed that the more frequently equipment was overhauled, the better protected it was against the likelihood of failure. The only problem was in determining what age limit was necessary to assure reliable operation. 1

Based on this assumption, it appears that the introduction of computerized maintenance management systems combined with the availability of computers would allow maintenance to solve the problem of when (what age) to overhaul the equipment in order to assure the required reliability.

The majority response of industry was to expand its' PM efforts to include virtually everything. However, the airline industry, lead by the efforts of F. Stanley Nowlan and Howard F. Heap, parted from the crowd and developed a maintenance process based on system functions, consequence of failure, and failure modes. Their development of the Reliability Centered Maintenance (RCM) process was based on maintenance and operations failure and reliability data being reported by airlines. Namely, In the case of aircraft it was also commonly assumed that all reliability problems were directly related to operating safety. Over the years, however, it was found that many types of failures could not be prevented no matter how intensive the maintenance activities.

Moreover, in a field subject to rapidly expanding technology it was becoming increasingly difficult to eliminate uncertainty. Equipment designers were able to cope with this problem, not by preventing failures, but by preventing such failures from affecting safety. In most aircraft essential functions are protected by redundancy features which ensure that, in the event of a failure, the necessary function will still be available from some other source. Although fail-safe and "failure-tolerant" design practices have not entirely eliminated the relationship between safety and reliability, they have disassociated the two issues sufficiently that their implications for maintenance have become quite different.

Nowlan, F.S. and Heap, H.F. Reliability-Centered Maintenance, Dolby Access Press, San Francisco, CA

1978.

A major question still remained, however, concerning the relationship between scheduled maintenance and reliability. Despite the time-honored belief that reliability was directly related to the intervals between scheduled overhauls, searching studies based on actuarial analysis of failure data suggested that the traditional hard-time policies were, apart from their expense, ineffective in controlling failure rates. This was not because the intervals were not short enough, and surely not because the tear down inspections were not sufficiently thorough. Rather, it was because, contrary to expectations, for many items the likelihood of failure did not in fact increase with increasing operation[al] age. Consequently a maintenance policy based exclusively on some maximum operating age would, no matter what the age limit, have little or no effect on the failure rate. 1

It was not until the 1980’s that alternatives, namely early forms of condition monitoring, to traditional PM programs began to migrate to the maintenance arena. This emergence of condition monitoring, which coincided with the development of low cost microprocessors and an ever-increasing computer literacy in the work force, supported the findings of Nowlan and Heap and others and reinforced the fallacy of the following two basic principles of the traditional PM program:

A strong correlation exists between equipment age and failure rate.

Individual component and equipment probability of failure can be determined statistically, and therefore components can be replaced or refurbished prior to failure.

These discoveries lead to the development of RCM. The principles of RCM were documented in Nowlan and Heap's seminal publication, Reliability-Centered Maintenance1. Their work, sponsored by the Office of the Assistant Secretary of Defense (Manpower, Reserve Affairs and Logistics), was published in 1978.

Additional independent studies performed in 1978 and 1982 confirmed Nowlan and Heap’s findings. In fact, the work performed in 1982 by the United States Navy expanded the work beyond aircraft and dealt with more down-to-earth equipment.

In all the studies, it was noted that a difference existed between the perceived and the intrinsic design life for the majority of equipment and components. In fact, it was discovered that in many cases equipment greatly exceeded the perceived or stated design life.

For example, SKF Industries, Inc. proposed changes in the method for evaluating bearing life from the original method (empirical) proposed by G. Lundberg and A. Palmgren in 1947. They found that "bearings exhibit a minimum fatigue life; that is, "crib deaths" due to rolling contact fatigue are non-existent when the aforementioned operating conditions [properly lubricated, mounted, operated and protected from dirt and moisture] are ii iii achieved."2 This lack of a predefined fatigue life for bearings greatly impacts the concept of a predetermined design life for rotating equipment where rolling element bearings are used and provides the basis for extending the time between overhauls and equipment replacement.

This process, known as Age Exploration (AE), was used by the U.S. Submarine Force in the early 1970s to extend the time between periodic overhauls and to replace time-based tasks with condition-based tasks. While the initial program was limited to Fleet Ballistic Missile (FBM) submarines it was expanded continually until it included all submarines, aircraft carriers, other major combatants, and ships of the Military Sealift Command (MSC). Furthermore, the Navy invoked the requirements of RCM and condition monitoring as part of the design specifications.

Development of relatively affordable test equipment and computerized maintenance management software during the last decade has made it possible to:

Determine the actual condition of equipment, and not have to rely on traditional techniques where the probability of failure is based solely on age and appearance instead of condition.

Track and analyze equipment history as a means of determining failure patterns and life cycle cost.

Also, it has only been recently accepted that while there are many different equipment failure characteristics, only a small number are age-related. This knowledge has increased the emphasis on condition monitoring, commonly, and in the author’s opinion inaccurately, referred to as predictive maintenance, and has resulted in extensive reviews of existing PM and interval-based overhaul/outages strategies by a large number of corporate and government organizations.

While RCM has long been accepted by the Department of Defense (DOD), the aircraft, spacecraft, and nuclear industries, it is a relatively new way of approaching maintenance for the majority of facilities. The benefits of RCM far exceed those of any one type of maintenance program.

Reliability-centered Maintenance is a comprehensive analytical approach identifying what must be done to deliver targeted asset performance. In fact, it is the only structured approach to Preventive Maintenance (PM) Work Identification that produces a Program that can be validated against a criteria of technical feasibility and worth doing. When RCM is effectively deployed, and its outcomes implemented, substantial impact on business performance is achievable.3

The question is whether there is economic justification for implementing RCM at DOS overseas facilities. Furthermore, it has been suggested that for small, non-critical, or

Harris, Tedric A. Rolling Bearing Analysis, Second Addition, John Wiley & Sons, New York, 1984.

3 Reliability Magazine, October 1997, Integrating RCM into An Equipment Reliability Program At Dofasco, F. Dunbrack & R. Thomas, Dofasco Inc.

iv inconsequential equipment that DOS should rely on redundancy, instead of improved procurement standards, commissioning, and periodic condition-monitoring, as redundancy will be cheaper in the long run.

Assuming that OBO will continue to procure and install to pre-RCM standards implies that approximately 85% of all rotating equipment4 will be installed with some type of deficiency, whether it be minor or major.

These installed deficiencies will reduce equipment life by some percentage and increase overall construction and O&M costs. Reduction in effective equipment life will be in the range of 50-67%5, 6 and 2.5 repairs can be avoided by extending the life of a pump, based on the impact of imbalance and misalignment on bearing and seal life. Assuming the pumps average 10 HP in size, and the average Post where vibration analysis will be used has 6 pumps, and there are 25 Posts where vibration analysis will be used, translates as follows:

$3,500/pump7 X 150 pumps X 2.5 = $1,312,500 in needless M&R

Cost to perform vibration monitoring on the pumps

8 trips of 2 weeks each for setup, training, and baseline $ 64,000

Labor for setup $ 72,000

Biennial monitoring (shipping datalogger) for 5 years $ 10,000

Data Analysis for 5 years $140,000

Expendables $ 5,000

Total $291,000

The direct cost avoidance is in excess of $1,000,000 for pumps alone. This estimate does not take into consideration the indirect costs avoided such as:

Loss of productivity

Collateral damage

Safety and security concerns

Procurement of emergency services

A similar case for vibration can be made for fans and the impact of oil analysis on diesel generator O&M costs.

As shown in the following figure, the impact of the thermography program in Africa has reduced the number of reported electrical fires8 by 38% from 1999 -2001.

4 Based on condition monitoring surveys performed at Singapore, Ottawa, Santiago, Bangkok, and Moscow 5 Dupont Pumps Running Program 6 Reliability Analysis of Bristol Myers Squibb Barceloneta pumps 7 RS Means Facilities Construction Cost Data 8 Fire Statistics provided by OBO/OM/Fire (Mr. Bruce Sincox)

FY99 FY00 FY01

Total

AF

Electrical

AF Electrical

While this manual is offered as a tool to assist Department of State (DOS) facility organizations in implementing and institutionalizing RCM to achieve and maintain the world-class facilities required to support the reliability goals inherent at any Post, it should be noted that all of the RCM tools will not be applicable to every Post. The following table should be used to determine what RCM tools to apply:

Large with Central Utilities

Large No Central Utilities TBD

Small No Central Utilities TBD

NOB

Major Rehabilitation

Acquisition TBD

This manual should be utilized by:

Facility Planners

Designers

Equipment Procurement Specialists

Construction Managers

Maintenance and Operations (M&O) personnel

Contract Planners v vi

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SECTION I INTRODUCTION

A. Definition

The following definition is used throughout and should be thoroughly understood prior to reading this manual.

Reliability Centered Maintenance (RCM) is the optimum mix of reactive, time- or interval-based, condition-based, and proactive maintenance practices. The basic application of each strategy is shown in Figure 1 1. These principal maintenance strategies, rather than being applied independently, are integrated to take advantage of their respective strengths in order to maximize facility and equipment reliability while minimizing life-cycle costs. These strategies are defined and discussed in detail in Section III, RCM Program Components.

Figure 1 1. Components of an RCM Program

RCM includes reactive, time-based, condition-based, and proactive tasks. In addition, a user should understand system boundaries and facility envelopes, system/equipment functions, functional failures, and failure modes, all of which are critical components of the RCM program.

• Small items

• Non-critical

• Inconsequential

• Unlikely to fail

• Redundant

• Subject to wear-out

• Consumable replacement

• Failure pattern

• Random failure patterns

• Not subject to wear

• PM induced

• RCFA

• Age

Exploration

• FMEA

Reliability Centered Maintenance

Reactive Preventive CBM Proactive

B. Types of RCM

There are several ways to conduct and implement an RCM program. The program can be based on rigorous Failure Modes and Effects Analysis (FMEA), complete with mathematically-calculated probabilities of failure based on design or historical data, intuition or common-sense, and/or experimental data and modeling. These approaches may be called Classical, Rigorous, Intuitive, Streamlined, or Abbreviated. Other terms sometimes used for these same approaches include Concise, Preventive Maintenance (PM) Optimization, Reliability Based, and Reliability Enhanced. All are applicable. The decision of what technique to use should be left to the end user and be based on:

Consequences of failure

Probability of failure

Historical data available

Risk tolerance

1. Classical/Rigorous RCM

a. Benefits

Classical or rigorous RCM provides the most knowledge and data concerning system functions, failure modes, and maintenance actions addressing functional failures of any of the RCM approaches. Rigorous RCM analysis is the method first proposed and documented by Nowlan and Heap and later modified by John Moubray, Anthony M. Smith, and others. In addition, this method should produce the most complete documentation of all the methods addressed here.

b. Concerns

Classical or rigorous RCM historically has been based primarily on the FMEA with little, if any, analysis of historical performance data. In addition, rigorous RCM analysis is extremely labor intensive and often postpones the implementation of obvious condition monitoring tasks.

c. Applications

This approach should be limited to the following three situations:

The consequences of failure result in catastrophic risk in terms of environment, health, or safety and/or complete economic failure of the business unit.

The resultant reliability and associated maintenance cost is still unacceptable after performing and implementing a streamlined type FMEA.

The system/equipment is new to the organization and insufficient corporate maintenance and operational knowledge exists on its function and functional failures.

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2. Abbreviated/Intuitive/Streamlined RCM

a. Benefits

The intuitive approach identifies and implements the obvious, usually condition-based, tasks with minimal analysis. In addition, it culls or eliminates low value maintenance tasks based on historical data and Maintenance and Operations (M&O) personnel input. The intent is to minimize the initial analysis time in order to realize early-wins that help offset the cost of the FMEA and condition monitoring capabilities development.

b. Concerns

Reliance on historical records and personnel knowledge can introduce errors into the process that may lead to missing hidden failures where a low probability of occurrence exists. In addition, the intuitive process requires that at least one individual has a thorough understanding of the various condition monitoring technologies.

c. Applications

This approach should be utilized when:

The function of the system/equipment is well understood.

Functional failure of the system/equipment will not result in loss of life or catastrophic impact on the environment or unit business.

For these reasons, the streamlined or intuitive approach is recommended for DOS facilities.

C. Background

From approximately 1960 until the late 1980s, preventive (interval-based) maintenance (PM) was the most advanced technique used by progressive facilities maintenance organizations. PM is based on the principle that equipment failures result largely from age or use. Therefore, PM tasks were performed at fixed intervals based on the calendar, operating hours, or cycles.

PM assumes that failure probabilities can be determined statistically for individual machines and components, and parts can be replaced or adjustments can be performed in time to preclude failure. For example, a common practice has been to replace or renew bearings after so many operating hours assuming that bearing failure rate increases with time in service.

Figure 1 2, Bearing Life Scatter, shows the failure distribution of a group of thirty identical 6309 deep groove ball bearings installed on bearing life test machines and run to failure. The wide variation in bearing life is obvious and precludes the use of any effective time-based maintenance strategy.

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The X-axis identifies the individual bearing being tested while the Y-axis is the number of revolutions achieved prior to fatigue failure of the individual bearing. It should be noted that the bearings are tested at above design loads to accelerate the failure rate. This is the standard procedure used to test bearings in order to determine the expected life of the bearing.

Fortunately, the development of affordable microprocessors and increased computer literacy in the work force during the 1990s has made it possible in many cases to identify the precursors of failure, quantify equipment condition, and schedule the appropriate repair with a higher degree of confidence than was possible when performing strictly interval-based maintenance based on usually erroneous estimates of when a component might fail. Also, it has been discovered recently that there are many different equipment failure characteristics, only a small number of which are age- or use-related. This new knowledge has increased the emphasis on Condition Monitoring (CdM), often referred to as Condition-Based Maintenance, which has caused a reduction in the reliance upon PM or interval based maintenance.

It should not be inferred from the above that all interval-based maintenance should be replaced by condition-based maintenance. In fact, interval-based maintenance is appropriate for those instances where an abrasive, erosive, or corrosive wear takes place, material properties change due to fatigue, embrittlement, etc. and/or a clear correlation between age and functional reliability exists.

Bearing Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

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Figure 1 2. Bearing Life Scatter

In addition, for those systems or components where no failure consequences in terms of mission, environment, safety, or Life Cycle Cost (LCC) exist, maintenance should not be performed; i.e., the equipment should be run to failure and replaced.

The concept of RCM should be adopted as the preferred strategy for performing maintenance. RCM applies maintenance strategies based on consequence and cost of failure. In addition, RCM seeks to minimize maintenance and improve reliability throughout the life cycle by using proactive techniques such as improved design specifications, integration of condition monitoring in the commissioning process, and the Age Exploration (AE) process. All of these will be discussed in detail in Section II, Reliability Centered Maintenance Approach.

D. Purpose of this Manual

The purpose of this manual is to provide DOS Headquarters and Post facilities personnel, M&O contractor personnel, and anyone else involved in maintenance and/or construction a single reference document to be used to identify the RCM requirements during the facility’s life cycle. This manual is intended to provide the following:

An Overview of RCM.

Contract Clauses for Planning, Design, Construction, and Maintenance.

Guidelines for Developing Procurement Specifications and Criteria.

Guidelines for Establishing Monitoring Intervals.

In-service Criteria for Facilities and Production Equipment and Systems.

Guidance Certification of CdM Personnel.

An Overview of CdM Technologies.

An Introduction to Root Cause Failure Analysis.

Guidelines for Performing Facilities Condition Assessment.

E. Applicability

This manual, particularly its recommendations and sample contract clauses, should be used for facilities planning, design, new construction, modification, equipment procurement, and M&O contracts. It should be used in preparing Requests for Proposals (RFPs) or Requests for Quotations (RFQs) for facilities contracts and contract modifications.