CORE Principles of ReliabilityCentered Maintenance
Rich Overman,
Overman CMRP
(904) 655-0787 Cell
Rich@coreprinciplesllc.com
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1
Introduction
• L
Late
t 1970’s
1970’ ushered
h d in
i a new era off assett
maintenance
• United States Department of Defense
published the seminal book entitled
Reliability-Centered Maintenance (RCM)
• Entire industries have g
grown from this one
book
• Growth brings variability
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Definition of RCM
• “a logical discipline for the development of
programs.”
g
– Nolan and
scheduled maintenance p
Heap
• “Reliability-centered
Reliability centered Maintenance: a process used to
determine what must be done to ensure that any
physical asset continues to do what its users wanted
it to do in its present operating context.” – John
Moubray
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Definitions of RCM
• RCM is “the best way to develop a maintenance
improvement program.
program ” – A.M.
A M Smith
• “RCM uses a cross-functional team to develop a
complete
l t maintenance
i t
strategy
t t
designed
d i d to
t ensure
inherent design reliability for a process or piece of
equipment.”
i
t ” – Doug
D
Pl
Plucknett
k tt
• RCM “is to identify components whose functional
failures can cause unwanted consequences to ones
plant or facility.” – Neil Bloom
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Process Variants
• Jack Nicholas categorized various RCM
p
processes:
– Classical
– Variants
– Derivatives
• Result is RCM has come to mean different
things to different people
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CORE Principles of RCM
• Not presenting:
– RCM process
– RCM philosophy
• Primary or CORE Principles of RCM
• Underlying principles upon which all RCM
processes are based.
b d
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Core Principles of RCM
• Components Fail
• Operational Impact
• Reliability Engineering Solutions
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Components Fail
• Without intervention everything will eventually fail
• Each component has failure characteristic
• Nolan and Heap identified six failure characteristics
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Components Fail
• Failure characteristic curves basis for all of
the RCM processes
• One fundamental principle of RCM is
identification of component failure
characteristic
• The
Th goall is
i to
t attempt
tt
t to
t understand
d t d failure
f il
characteristic to identify appropriate
i t
intervention
ti
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Failure Characteristics
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But There is More
• It is intuitively obvious that components will fail
• It is possible to intervene in some way to try to
pprevent all failures
• It is equally intuitively obvious that no company can
afford to try to prevent all failures
• The primary purpose of RCM is to identify the
appropriate intervention
• Simply recognizing that components fail is not
sufficient
ffi i t
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Core Principles of RCM
• Components Fail
• Operational Impact
• Reliability Engineering Solutions
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Operational Impact
• Every component failure has some degree of
operational impact
• Direct operational impact ranges from shutting
down to none
• Indirect operational impact is to drain resources
• Every failure requires resources that could be more
efficiently and effectively used to increase company
value
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Operational Impact
• Goal of RCM
–
–
–
–
evaluate
categorize
Prioritize
understand the operational impact of failure
• Identify the appropriate intervention.
intervention
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But There is More
• Components fail
• They impact operations
• That knowledge, by itself, is not sufficient
to identify appropriate intervention
• Need a logical way of organizing and
evaluating
l i information
i f
i to make
k soundd
intervention decisions
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Core Principles of RCM
• Components Fail
• Operational Impact
• Reliability Engineering Solutions
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Reliability Engineering Solutions
• Reliability Engineers used analytical
q
for yyears
techniques
– Failure Modes, Effects, and Criticality Analysis
(
(FMECA)
)
– Stochastic analyses
• Only logical to apply these techniques to the
issue of failure intervention.
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FMECA
• FMECA provides logical method for identifying
failures and evaluating operational impact
• Every component failure leads to loss of a function
• Loss
oss of
o function
u ct o has
as process
p ocess effect
e ect
• FMECA process identifies and documents
–
–
–
–
–
Functions
Functional failures
F il
Failure
modes
d
Effects of failure at various levels
C i i li analysis
Criticality
l i categorizes/prioritizing
i / i i i i failure
f il
modes
d
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FMECA
• Importance of FMECA to RCM process cannot be
overstated
• Understanding operational impact of failure is
crucial to developing appropriate intervention
• “a good FMECA will not guarantee a good RCM
analysis but a bad FMECA will guarantee a bad
RCM analysis.”
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Stochastic Analysis
• FMECA is great existing Reliability Engineering
tool for understanding operational impact of failures
• Not sufficient for developing intervention schemes
• FMECA
C iss foundation
ou dat o but not
ot eend
d oof RCM
C pprocess
ocess
• Stochastic analysis is other Reliability Engineering
tool that needs to be employed
• Most common stochastic analysis used in RCM is
Weib l analysis
Weibul
anal sis
• Weibul analysis can identify failure characteristic
curve applicable
li bl to failure
f il
mode
d
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Relating Failure to Intervention
• Failure characteristic defines intervention
• Scheduled overhaul/replacement would not work for
infant mortality characteristic
• A random
a do failure
a u e characteristic
c a acte st c iss more
o e appropriate
app op ate
for applying a predictive maintenance
• A wear out characteristic would benefit from either
a predictive maintenance or overhaul/replacement
intervention
• Stochastic techniques provide information to
determine intervention interval
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Function Preservation
A
Classical RCM asks:
How do I keep
fl id flowing
fluid
fl i out
of tank?
Traditional analysis asks:
B
How do I keep the
pump
p
p operating?
p
g
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Function Preservation
A
What are ways to keep
fluid flowing out of
Tank B other than
keeping the pump
running?
i ?
How do I keep
fl id flowing
fluid
fl i out
of tank?
• Bypass valve
• Standby pump
B
• Keep tank B full enough to
give time to change a failed
pump
• With a functional approach
many alternatives are available
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7 Steps in the RCM Process
1. System Selection
2. Systems Boundary Definitions
3. System Description
4. Identify System Functions &Functional Failures
5. Failure Modes and Effects Analysis (FMEA)
6 Task
6.
k Selection
S l i
7. Program Implementation
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Source: William A. Keeter, MQS and Jack Nicholas
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SAE Standard
1. What are the functions, performance standards in the
present operating context? (Function)
2. In what ways does it fail to fulfill its functions? (Functional
failure))
3. What causes each functional failure? (Failure mode)
4. What happens when each failure occurs? (Failure effects)
5. Why does the failure matter (Failure consequences)
6 What can be done to predict or prevent each failure?
6.
7. What should be done if a suitable task cannot be found?
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Example Analysis – Water Jet Machine
• Nagging Failures – Worn and failed tips
• Lots of down time
• Cause – “Dirty” Water
• Source – Versatile Reliability-Centered
Reliability Centered
Maintenance
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System and Boundaries
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Water Jet Reclamation System
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Water Jet RCM Analysis
•
•
•
•
•
•
•
•
7 Functions
14 F
Functional
ti l Failures
F il
47 Failure Modes
8 Inspections
4 Overhaul/discard
1 Failure finding
25 R
Run-to-failure
t f il
Estimated annual savings $334K
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Conclusion
• All RCM processes apply CORE Principles of RCM
• Must be applied to identify appropriate failure
intervention
• Component failure must be understood
• Operational impact assessed
• Reliability Engineering tools applied
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Conclusion
• Each RCM process available today applies the CORE
Principles of RCM to varying degree
• Degree applied is indicative of overall benefit
• If CORE Principles of RCM applied superficially - some
but limited benefit
• More rigorous application of the CORE Principles of RCM
- enhanced benefits
• Degree to which CORE Principles of RCM are applied
affects
ff
cost off analysis
l i
• The more a company is willing to invest in RCM the more
b fit they
benefit
th can expectt
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