Rcm

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The RCM Guide
Reliability Centered Maintenance

The RCM Guide
1. Definitions

1. RCM definitions (1)
• Reliability Centered Maintenance (RCM) is a
methodology used to determine the right
maintenance tasks to ensure that any
physical asset or system continues whatever
its users want it to do, in its present
operating context

1. RCM definition (2)
Reliability
- The probability that equipment will not
fail in a given time period
- = a measure of the frequency of
downtime

1. RCM definition (3)
Maintenance
- Any activity carried out on an asset in
order to
- ensure that the asset continues to
perform its intended functions
- repair the asset

The RCM Guide
2. History

2. RCM History
• 60’s: RCM developed in the airline industry
• 70’s: RCM used in the army and the
American Navy
• 1978: first use of the term “Reliability
Centered Maintenance” in Nowlan & Heap’s
book: this book showed that a strong
correlation between age and failure rate did
not exist
• 80’s - 90’s: transfer of the RCM methodology
to other industrial sectors (railways,
chemical industry)

The RCM Guide
3. Objectives

3. RCM Objectives (1)
• Determine the optimum maintenance program
• Optimize your maintenance efforts
• focus on the most important functions of the systems
• avoid maintenance actions that are not strictly
necessary
• Strive for the required reliability
• at the lowest cost
• without sacrificing safety
• without sacrificing the environment

3. RCM Objectives (2)
• Establish maintenance practices which focus
more on
• the functional importance of a piece of equipment and
its failure/repair history
• and less on
• vendor PM recommendations
• traditional “time-directed” overhaul tasks

The RCM Guide
4. Principles

4. RCM principles
• 4.1. RCM is Business-Oriented
• 4.2. RCM is Function Oriented
• 4.3. RCM is System Focused
• 4.4. RCM investigates how Equipment Fails
• 4.5. RCM defines the best Maintenance
Strategy based on the consequences of
failures
• 4.6. RCM acknowledges Design Limitations
• 4.7. RCM is an Ongoing Task

4. RCM principles
4.1. Business oriented
• Maintenance is business oriented (not only
technical oriented):
• operations efficiency
• quality
• cost
• safety
• environment

4. RCM principles
4.2. Function oriented
• RCM focuses on preserving the functions of
equipment, not on preserving the equipment
itself
• Equipment function: what its users want it to do
• 2 function categories
• primary functions: speed, output, product quality
• secondary functions: safety, comfort, environmental
integrity

4. RCM principles
4.3. System focused
• RCM is more concerned with maintaining the
system function, than individual component
function
• If the system still provides its primary function if
a component fails, the component is allowed to
run to failure

4. RCM principles
4.4. RCM investigates how equipment fails (1)
• Failure:
• a failure is the inability of an equipment, system or
plant to fulfill one or more of its intended functions
• Failure mode:
• what is wrong
• what we need to prevent or physically fix
• Failure cause:
• why it went wrong
• Failure effect:
• the consequence of the failure mode, when it occurs

4. RCM principles
4.4. RCM investigates how equipment fails (2)
• Failure patterns:
• the relationship between the probability of failure of
an item, and its age (see Maintenance Management
Guide)
• RCM seeks to know the probability of failures at
specific ages
AGE
Prob. Of
Failure

4. RCM principles
4.5. RCM defines Maintenance Strategy
• Based on the consequences of failures, the
best maintenance strategy is defined
• Run to Failure (RTF)
• Preventive Maintenance (PM) ·
• Predictive Maintenance (PDM)
• Proactive Maintenance (PAM)
• Condition-based or predictive maintenance
strategies are favored over traditional time-
based methods

4. RCM principles
4.6. RCM recognizes Design Limitations
• A maintenance program can only maintain the
level of reliability inherent in the system design
• No amount of maintenance can overcome poor
design
• Maintenance knowledge is fed back to designers
to improve the next design

4. RCM principles
4.7. RCM is an ongoing task
• The full benefit of RCM is only achieved when
operation and maintenance experience is
continuously fed back into the analysis process.

The RCM Guide
5. Tools

5. RCM tools
• 5.1. Selection and prioritizing tool
• Pareto analysis
• 5.2. Failure analysis tool
• FMECA
• 5.3. Reliability Modeling tools
• Reliability Block Diagram
• Fault Tree
• 5.4. Decision Tool
• Decision Tree analysis

5. RCM tools
5.1. Pareto analysis (1)
• Pareto analysis is a selection and prioritizing tool
• Pareto analysis (sometimes referred to as the
80/20 rule and as ABC analysis) is a method of
classifying items, events, or activities according
to their relative importance
• Pareto analysis is based on the premise that 80
% of problems are due to 20 % of the possible
causes

5. RCM tools
5.1. Pareto analysis (2)
• Steps
• sort data in descending order of importance
• calculate individual percentages for each category
• calculate cumulative percentages for each category
• all categories with cumulative % less than or equal to
80 % can be selected for further review

5. RCM tools
5.1. Pareto chart
Problem Causes
%
20
40
60
80
100
A B C D E F ... O P
42
62
80
100

5. RCM tools
5.2. FMECA (1)
• Failure Mode, Effect and Criticality Analysis is a
Failure Analysis tool
• It is a step-by-step procedure for the systematic
evaluation of the failure effects and the criticality
of potential failure modes in equipment and plant
• A standard form (next slide) must be filled out

5. RCM tools
5.2. FMECA (2): standard form
Item Function Failure mode Failure cause Failure effect Failure detection Failure isolation Actions Severity

5. RCM tools
5.3.1. Reliability Block Diagram (RBD) analysis (1)
• RBD is a Reliability Modeling tool, and is
constructed to assess the overall system
reliability
• A Reliability Block Diagram graphically
represents the logical interaction of components
within your systems
• The components are arranged by blocks, and
are related reliability-wise

5. RCM tools
5.3.1. Reliability Block Diagram (RBD) analysis (2)
A
D
B
0.9
0.8
0.7
A,B,..: Components
Numbers: availability

5. RCM tools
5.3.2. Fault Tree Analysis (FTA) (1)
• FTA is a Reliability Modeling tool
• FTA specifies a top event (ex. a fire) to analyze,
followed by identifying all of the elements in the
system that could cause the top event to occur
• A symbolic logic diagram with AND/OR gates is
constructed

5. RCM tools
5.3.2. Fault Tree Analysis (FTA) (2)
Top event
Failure 1 Failure 2
OR
Failure 3 Failure 4
AND

5. RCM tools
5.4. Decision Tree analysis (1)
• A Decision Tree Diagram is a graphical
illustration in which lines branch out from a
central point without forming any closed loops
• The Decision Tree Diagram guides the user
through a question-and-answer process
• Options are ranked in an order of preference

5. RCM tools
5.4. Decision Tree analysis (2)
?
?
?
YES
YES
NO
NO
YES NO
Option 1 Option 2 Option 3 Option 4

The RCM Guide
6. RCM analysis

6. RCM analysis
• 6.1. Study preparation
• 6.2. System selection and definition
• 6.3. System function definition
• 6.4. Functional failures definition
• 6.5. Failure modes analysis
• 6.6. Failure consequences assessment
• 6.7. Selection of maintenance actions
• 6.8. Data collection and documentation

6. RCM analysis
6.1. Study Preparation
• Establishment of an RCM project group
• one person from the maintenance function
• one person form the operations function
• an RCM specialist
• Definition of objectives and scope of the analysis
• Definition of boundary conditions with respect to
safety and environmental protection

6. RCM analysis
6.2. System Selection and Definition
• The description of the assembly hierarchy (plant
register) is a good standing point for system
selection and definition
• Tools:
• Pareto analysis,
• Reliability Block Diagram analysis,
• Fault Tree Analysis
To which systems are an RCM analysis beneficial compared with more
traditional maintenance planning?
At what level of assembly (plant, system, subsystem …) should the
analysis be conducted?

6. RCM analysis
6.3. System function definition
• Identify and describe the system’s required
functions and performance standards in its
present operating context
• Describe input interfaces required for the
system to operate
What are the functions and the associated
desired standards of performance of the asset
in its present operating context?

6. RCM analysis
6.4. Functional failures definition
• Identify the ways in which
• the system might fail to fulfill its functions
• the system functions at an unacceptable level of
performance
In what way can the asset
fail to fulfill its functions?

6. RCM analysis
6.5. Failure modes analysis
• The objective of this step is to identify the events
which cause the failure
• normal wear
• human errors
• design
• Tool: FMECA
What causes each functional failure?

6. RCM analysis
6.6. Failure consequences assessment
• Failures which affect production / operations
• Failures which threaten
• safety
• the environment
• Failures which entail the direct cost of repair
• Tool: FMECA
What happens when the failure occurs?

6. RCM analysis
6.7. Selection of Maintenance Actions (1)
• Only applicable and cost-effective tasks may be
selected
• Applicability:a PM task will be applicable if it can
eliminate a failure, or at least reduce the probability of
occurrence to an acceptable level - or reduce the
impact of failures!
• Cost-effectiveness: the cost of performing the
maintenance is balanced with the "cost" of not
performing it.
What should be done to predict or prevent
each failure?

6. RCM analysis
6.7. Selection of Maintenance Actions (2)
• Tool: Decision Tree analysis
• Options
• do nothing: run to failure
• prevent: scheduled or non-scheduled tasks
• predict: checking the condition of equipment and
detecting failure
• redesign
• equipment
• process
• procedures

6. RCM analysis
6.8. Data Collection and Documentation
• The data necessary for the RCM analysis may
be categorized and collected in the following
three groups:
• Design data
• Operational data
• Reliability data
• The revised tasks and procedures must be
documented in a way that ensures that they will
be easily understood and performed by the
people who do the work

The RCM Guide
7. Implementation

7. RCM implementation
Eight implementation steps (1)
1. Define the scope and objectives of the
project
2. Establish review groups
• facilitator
• project manager
• operations personnel
• functions and performance standards
• maintenance personnel
• types of failures
• most appropriate condition monitoring techniques
• maintenance and operations personnel
• consequences of identified failures

3. Train the review group
4. Estimate the amount of time to review the
selected equipment
5. Plan meetings
• date
• time
• location

6. Plan senior management audits
Senior management has to agree on
• definition of functions and performance
standards
• identification of failure modes
• description of failure effects
• assessment of failure consequences
• selection of tasks
7. Implement the selected tasks
8. Document the tasks and procedures

The RCM Guide
8. Benefits

8. RCM benefits (1)
• Cost saving
• shift from time-based to condition-based work
• workload reduction
• spare part usage reduction
• improved operation performance
• Rationalization
• unnecessary preventive work is eliminated
• Improved safety
• Improved environmental integrity

8. RCM benefits (2)
• A precise and comprehensive maintenance
database
• during the analysis, information is gathered in a
coherent form
• Education
• improved overall level of skill and technical knowledge
• Improved teamwork
• Greater motivation of individuals

The RCM Guide
9. CMMS and RCM integration

9. CMMS and RCM integration
• Constant evolution to integrate RCM
software in the Computerized Maintenance
Management Systems:
• Reliability Prediction Programs
• Reliability Modeling Programs
• FMEA / FMECA Programs
• RCM databases
• Links:
• http://www.relexsoftware.com/
• http://www.sohar.com/software/meadep/
• http://www.itemsoft.com/

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Rcm

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