Reliability is of a great interest for me because I studied it during my MSc. of Eng. and because I do believe in it: "a reliable asset is a safe asset"... One of the many ways to improve the reliability of an asset is to implement a Reliability-Centered Maintainance.

1. 7/26/2011
Content
1. RCM Introduction
2. Maintenance Strategy Review
3. Introduction to Functional Analysis
Reliability-Centred Maintenance
4. Introduction to FMECA
“An Introduction to” 5. Function selection
6. RCM Tasks evaluation
7. RCM Tasks selection
Jean-Baptiste MARTIN 8. RCM Implementation
9. Feedback
Risk, Safety & Reliability Consultant
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RCM Introduction RCM Introduction
 Logical and systematic approach to define a routine  Started in 1960’s – Federal Aviation Administration
maintenance program composed of cost-effective tasks (USA) concerned with high crash rate
that preserve important functions
 1978: “Reliability-Centred Maintenance” Report by
 Process to establish the safe minimum levels of United Airlines Engineers (for US Defence)
maintenance  Basis of Maintenance strategy
 Promulgated in 1980s
 Process to determine the maintenance requirements of
any physical asset in its present operating context  Used these days (slightly modified) by commercial
aviation industry
“Why” maintenance should be conducted on equipment
instead of “What” maintenance tasks could be done
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RCM Introduction RCM Introduction
 First RCM approach  RCM strength
 Frequent overhaul and parts replacement  HSE levels are met or exceeded
 Costly and did not improved reliability  Increase cost effectiveness
 Maximize equipment availability
 Why Aviation Industry ?
 Reduce repairing time
 The “Fix it when it breaks” approach was obviously not
acceptable for airplanes !  Set up a new data base
Availability
 Nowadays derivatives of RCM implemented in many
other industries
Maintenance Cost
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RCM Introduction Maintenance Strategy Review
 RCM weakness Functional analysis
 Requires significant effort and focus (labor intensive)
FMECA F
 Needs some specific data to be available or assumed
e
(MTBF etc.)
e
 Yes / No answers are required – but everything is not Significant functions selection
always black / white d
 Where to stop ? Level of details should be defined at the b
RCM task evaluation
beginning a
c
RCM task selection
k
RCM implementation
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Maintenance Strategy Review Maintenance Strategy Review
1930’s 1950’s – 1980’s 2000’s  Different maintenance strategies
 On failure  Increased demand of goods  Stringent economical  On failure: “We need to fix it quickly !”
maintenance (World war II) environment
 “Feeling”: “Why not maintaining it tomorrow before
 Downtime not an  Increased automation  Need to reduce operating lunch?”
issue & maintenance costs
 Higher maintenance cost
 Based on experience: “If some maintenance is good, then
 6 , TPM, RBI, RCM a lot more must be better !” or “We have always done it
 Scheduled Overhaul that way!”
Planning Systems
Computerisation
Maintenance is a process NOT an event
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Maintenance Strategies Review Maintenance Strategy Review
 Need for MSR  Dangers of MSR
 Safety, cost-effective &  Fall into the technology
technical viability trap
 Produce an optimised  Use inappropriate
maintenance programme technology
 Document all information  Fail to set Functional analysis
used in making decisions objectives/success
 Identifies important criteria
monitoring parameters  Fail to address cultural
 Allows for feedback & issues
continuous improvement  Fail to gain management
support
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Introduction to Functional Analysis Introduction to Functional Analysis
 Integrated Definition (IDEF0)  Integrated Definition (IDEF0)
 Function: an activity, process, or transformation identified by
a verb or verb phrase that describes what must be
Control accomplished.
 Input: data or consumables that trigger
the activity
 Control: commands which guide or Control
Input Function Output influence the activity
Input Function
Mechanism
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Introduction to Functional Analysis Introduction to Functional Analysis
 Integrated Definition (IDEF0)
 Mechanism: means, tools or people used to accomplish
the activity (allocation of activities)
 Outputs: data or products that are produced by the
activity
Function Output
Mechanism
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Maintenance Strategy Review Introduction to FMECA
 Failure Modes, Effects and Criticality Analysis
 Extension of FMEA
 Identification of all possible failures within a system, the
possible effects of these failures and any potential
consequences
FMECA
 Ranking of these potential problems in terms of
“Criticality”
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Introduction to FMECA What is the function?
 Two categories of functions
 Primary Functions: usually fairly easy to recognise. They
are the main reasons why assets have been acquired
 Secondary Functions: less obvious than the primary, even
though their failure can sometimes have more serious
consequences (Environmental, Safety, Control / Comfort,
Appearance, Protection, Economy etc.)
 Function description: “To be capable of”, “To provide”
What is the
function ?  Example: Pump
 Primary function: To pump oil from well to refinery
 Secondary function: To contain the fluid
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What is the function? What is the function?
 Operational mode – Example is Airplane  Performance standards
 Taxi  Performance standards specify the boundary between
 Take-off satisfactory performance and failure
 Climb  Performance standards describe the minimum acceptable
performance requirement associated with functions rather
 Cruise
than the item design capability
 Descent
 Some performance standards can be drawn directly from
 Approach the operating context
 Flare-out
 Roll
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What is the function? Introduction to FMECA
 “What are the items supposed to do …”
 Define The Primary Function “What It Is Required To Do”
- Not The Design
 Define The Performance Standards “Quantitative rather
than Qualitative”
 Define The Tolerances On The Performance Standard
“Minimum, Maximum, Nominal Etc.”
In what
way can
it fails?
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In what way can it fails? In what way can it fails?
 Functional Failure: inability of an asset to fulfil a
function with an acceptable level of performance for When capability drops below desired
the user performance after the asset commissioned
 Covers • Most common
 Complete loss of function
 Situations where the asset still functions but performs When desired user performance raises above
outside acceptable limits capability after the asset commissioned
 Described as “Fails to be capable of …”
When the asset is not capable of doing what is
wanted from the beginning
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Introduction to FMECA What’s the failure modes ?
 A failure mode is any event which could cause a
functional failure - past, future & currently prevented
 All failure modes which are reasonably likely to cause
a functional failure should be identified
 The root cause of failure modes should be identified
 Black boxing is acceptable under certain
circumstances
What are the failure
modes?
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What’s the failure modes ? Introduction to FMECA
 Failure detection: the means by which functional
failures become evident and how their failure
 Evident: lights, buzzers, smoke etc.
 Hidden: detectable by maintenance only
 Example: the failure mode “fail to start” of a pump with
operational mode “standby” is an example of a hidden
failure.
What
are the
effects
of
failure?
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What the effects of failure? FMECA
 Effect identification should describe
 The effects on safety or the environment
 The effect on production/operation (economic or service
level)
 Potential secondary damage to other equipment
 Downtime or repair actions with estimated time (loss of
function to the restoration of function)
Does it matter?
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Does it matter? Does it matter?
 Severity categories (examples)  Ranking of Risk Priority Number (RPN)
 Hidden or evident under normal conditions  O = the rank of the occurrence of the failure mode
 Safety or environmental  S = the rank of the severity of the failure mode
 Operational (economic or service level)  D = the rank of the likelihood the failure will be detected
 Non-operational before the system reaches the end-user/customer
 Etc.  The smaller the RPN the better – and – the larger the
worse
RPN = S x O x D
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Does it matter? Does it matter?
 Severity Ranking Example  Occurrence Ranking Example
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Does it matter? Maintenance Strategy Review
 Detection Ranking Example
Significant functions selection
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Functions Selection Functions Selection
 Function selection
 Significant Function (SF) – A function whose failure will
result in adverse consequences with respect to safety, the
environment, operations, or economics
 Non-significant Function (NSF) – A function whose failure
will have no adverse safety, environmental, operational,
or economic consequences
 SF Selection Logic diagram
 Apply to every function that has the potential of being
significant
 First question in the logic flow that evokes a “YES”
answer dictates that the function is significant
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Maintenance Strategy Review RCM decision logic
RCM task evaluation
 √ = Optional
 M = Mandatory
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RCM task evaluation RCM task evaluation - OC
 Task evaluation: process used to determine which of  On Condition task (predictive)
several options is best suited to
 To detect potential failure
 Prevent a failure mode from occurring
 And then take action to prevent the functional failure or to
 Reduce the consequence of its failure to a level that is avoid the consequences (outside of RCM scope)
acceptable
 Each option has unique criteria that determine if the task is
appropriate for the failure mode
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RCM task evaluation - OC RCM task evaluation - SR
 Development of OC task  Scheduled Replacement
 Do we have any prior warning of the failure?  Removes or restores the item at a predetermined age
 What is this warning? regardless of whether or not failure is impending
 How long will it take to fail from the prior warning?  SR development
 Is It consistent in time?  Do we have a reliable age projection (Wear Out)?
 Will it give us enough time to respond appropriately?  Will most items reach this age?
 Can a task interval be developed that reduces the
probability of failure to an acceptable level?
If YES to ALL: OC is technically feasible
If YES to ALL: SR is technically feasible
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RCM task evaluation - SR RCM task evaluation - FF
 Wear out  Failure Finding task
 Increase in the conditional probability of failure with age  Objective: prevent or at least reduce the probability of the
associated multiple failure
 Life limit
 Check a hidden function at regular intervals to find out
 Safe Life Limit (SLL) whether it has failed
 Economic Life Limit (ELL)  Multiple failure is when the protected function fails and
the protective device is also in a failed state
 FF task should avoid dismantling protective devices or
otherwise disturbing them
ELL
SLL
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RCM task evaluation - FF RCM task evaluation - OFM
 Failure Finding Interval  On Failure Maintenance task valid only if:
 MTBF of protective device  A suitable proactive or failure-finding task cannot be
 Desired availability of the device found for a hidden failure, and the associated multiple
failure does not have safety or environmental
consequences
Availability (%) 99.99 99.95 99.90 99.50 99.00 98.00 95.00  A cost-effective proactive task cannot be found for evident
Interval (% of 0.02 0.10 0.20 1 2 4 10 failures which have operational or non-operational
MTBF) consequences
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RCM task evaluation - RD Maintenance Strategy Review
 Re-Design definition
 A change in the physical configuration of an asset or
system
 A change to a process or operating procedure
 A change to the capability of a person, usually by training RCM task selection
 Re-Design if only
 The multiple failure could affect safety or the environment
 If the multiple failure does not affect safety or the
environment but RD economically justified
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RCM Task selection RCM Task selection
 Three types of outputs depending on the option  Cost
 Perform PM tasks (OC, FF, SR)  Cost of options are typically compared by normalizing
 Allow the failure mode to occur, then take corrective them to a common unit such as cost per unit operating
action (OFM) hour, cost per hour, or cost per cycle
 Take some other action, such as redesigning the item  Operational consequences
(RD)
 If the operational impact is considered more important,
 BEST solution: comparing each of the available options the more expensive task should be chosen
with the others
 How to define which one is the BEST ?
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Maintenance Strategy Review RCM implementation
 Build RCM Team
 RCM Facilitator
 Production
 Maintainers
 HSE
RCM implementation
 Ensure RCM methodology is followed
 Keep the review at the right level
 Document all the RCM information
 Chair and manage the meetings / workshops (ensure
time aspects and involvement of all members etc.)
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RCM implementation RCM implementation
 Make documents available  Align tasks for effective resources and production use
 Plant overall plot plan ; layouts
 Process flow Diagram  Schedule routine maintenance
 Operating & Maintenance manuals
 Incorporate into SAP
 Existing maintenance strategy
 Maintenance history record
 Define context : objectives
 Process / product affected
 Applicable HSE regulations
 Process availability requirements
 Business risk & reliability
 DownTime economics
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RCM implementation RCM implementation
 Alternative to detailed RCM (medium criticality  Alternative to detailed RCM (Low criticality functions):
functions): Generic RCM MS Review
 Define equipment type (pump, filter etc.)  Analyse vendors recommendations
 Define failure modes from previous experience  Define failure modes from previous experience
 Define failure consequences
 Define failure consequences
 Compare existing vendor tasks with failure modes
 Define failure characteristics
 Determine if task is
 Determine task or strategy most applicable  (R) retained
 Apply task routines to medium criticality equipment  (U) updated
generically  (C) changed or
 Ensure consequences are still applicable  (D) deleted
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Maintenance Strategy Review Feedback
 RCM analysis will never be perfect because
 Numerous decisions have to be made on the basis of
incomplete or non-existent hard data
 The assets, and the processes of which they form part,
Feedback will be subject to continuous change
 The perspectives, attitudes and priorities of people will
be changing continuously
 Technological advancements may affect / invalidate
analysis decisions
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Feedback Conclusion
 The RCM should be periodically reviewed  RCM
 Is an effective mean of improving production availability
 Collect data on the effectiveness of the maintenance and reducing maintenance cost
program through in-service equipment performance
 But has some weaknesses …
 To investigate and correct maintenance related problems
 A strong RCM team is needed
 To identify hardware design and manufacturing
 Management willingness and support is required
deficiencies
 Close cooperation between maintenance and production
 To document specific resource savings that are achieved
through the RCM process  Basics equipment information required as a starting point
Compare cost, manpower, and readiness levels achieved by
previous maintenance approach to the revised RCM strategy Let’s implement RCM on a pilot system !
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