maintenance management and rcm

8/19/2019 Maintenance Management and RCM

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State of the Industry in ReliabilityCentered Maintenance

Presented by Marius BassonGlobal Head of Reliability at CH2M HILL

Xenia, OHJune 5, 2014

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Maintenance Paradigms

1. The Primary objective of maintenance is to optimize plantavailability at minimum cost

2. Maintenance is all about preserving physical assets3. Most equipment becomes more likely to fail as it gets older

4. Proactive maintenance is all about preventing failure5. Generic maintenance programs can be developed for most types

of physical assets6. Comprehensive data about failure rates must be available before it

is possible to develop successful maintenance strategies7. The probability of catastrophic failures can be almost eliminated

by fitting suitable protection

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Maintenance Paradigms (continued)

8. There are three basic types of maintenance: predictive, preventiveand corrective

9. The frequency of predictive tasks should be based on thefrequency of the failure and/or the criticality of the item

10. Maintenance policies should be formulated by managers andmaintenance schedules drawn up by suitably qualified specialistsor external contractors (a top-down approach)

11. The maintenance department on its own can develop a

successful, lasting maintenance program12. Equipment manufacturers are in the best position to develop

maintenance programs for new physical assets

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1. Primary objective of maintenance

Primary FunctionThis is normally the reasonwhy the asst exist

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Secondary Functions• Environmental integrity• Safety requirements• Structural integrity• Control requirements• Containment• Comfort• Appearance• Protection• Economy and Efficiency• Superfluous function

Example: The primary function of a wastewater pumping station is transfer wastewaterfrom the collection system to the treatment pant at a minimum rate of 600 MGD.Examples of secondary functions may be to generate an alarm when wet well levelrises above normal operating conditions or to shut down the motor in the event of anelectrical overload.


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2. Defining maintenance

Old ParadigmMaintenance is all aboutpreserving physical assets

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New ParadigmMaintenance is all aboutpreserving the functionsof physical assetsthroughout their usefullives

We have seen that every asset (system or subsystem) has at least oneand normally several functions (primary and secondary).

Preserving asset functions leads to optimization of the maintenanceprogram where on the other hand preserving physical asset could lead to

over maintenance and superficial maintenance.


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Maintenance must causethe asset to continue

to function in this zone

Maintenance cannot raisethe performance of the assetbeyond its built-in capability(or inherent reliability)

Desired performance(what the user wants it to do)

Built-in capability(what the asset can do)

If we are to apply a process used todetermine what must be done toensure that a physical assetcontinues to do whatever its users

want it to do in its present operatingcontext we need to:

Know exactly what its userswant it to do

Be certain that the asset iscapable of doing what its userswant from the start


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Example:When we maintain an oil pipeline800 miles long (by doing the samemaintenance along the entirelength), we are maintaining what itis (asset focused) rather than whatit should be (functional focus). Weneed to understand the user

requirements and asset capabilityto optimize the maintenanceprogram.


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3. Characteristics of failure

Old ParadigmMost equipment getsmore likely to fail as they

get older

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New ParadigmFailure characteristicsindicate that for less than20% of all failures there is adirect relationship betweenthe age of the equipmentand the likelihood of failure.

The traditional view was that most failures occur on or at about thesame age, and most maintenance programs were based on this belief.It is also true that for many failures there are no effective form ofproactive maintenance (predictive or preventive).Intrusive

maintenance may increase the likelihood of failure.


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Characteristics of failure (Traditional view)

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C o n

d i t i o n a

l

P r o

b a b i l i t y o f

F a i l u r e

LIFE Most items

wear out atabout thesame age

Time (age)Failure Pattern B


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Third Paradigm – Reality of failure

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Pattern A: The "Bathtub Curve"High infant mortality, then a low level ofrandom failure, then a wear-out zone

A

Pattern B: "The Traditional View"Random failure then a wear-out zoneB

Pattern C: Steady increase in the probability of failureC

Pattern D: A sharp increase in the probability of failuresettling down to random failure

D

Pattern E: Random FailureNo relationship at all between how old it is andhow likely it is to fail

E

Pattern F: The "Reversed J" CurveHigh infant mortality then random failure

F

4 %

2 %

5%

7%

14 %

68 %


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4. Proactive maintenance

Old ParadigmProactive maintenance isall about preventing failure

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New ParadigmProactive maintenance isabout preserving assetfunctions (ensureequipment continuous todo what its user want it todo)

All proactive maintenance (routine maintenance) is planned but not allplanned maintenance is routine. In some cases reactive maintenance(repair or corrective) may be more effective.


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4. Proactive maintenance – Preventivemaintenance for “age related” failures

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Time (age) C o n

d i t i o n a

l P r o

b a b i l i t y o f

F a i

l u r e

Life

Carry out scheduled overhaul (scheduled restoration)or planned replacement (scheduled discard) justbefore reaching the wear-out zone

Wear-outzone

Preventive maintenance – Scheduled restoration and scheduled discardtasks may be feasible for age related failures


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4. Proactive maintenance – Predictivemaintenance

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P e r

f o r m a n c e o r

C o n

d i t i o n

( R e s

i s t a n c e

t o S t r e s s )

Time

OK

Point where failure starts to occur(not necessarily related to age)P = Potential Failure(point where we can findout that it is failing)P

•

•

FunctionalFailure


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4. Proactive maintenance – Predictivemaintenance - failures that give us a warning

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On-condition techniques fall into 4 basic groups:

Condition monitoring Use specialized equipment to monitor the condition

of other equipmentProduct quality monitoring Such as Statistical Process Control

Machine performance monitoring Temperatures, pressures, power consumption, etc.

The human sensesSight, hearing, touch, taste and smell

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X 1 000


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4. Proactive maintenance – Functionalchecks for hidden failures

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Hidden functions - equipment(protective devices) fail in sucha way that no one knowswhether they are still working or

not during normal operation

Hidden failures only becomeevident when somethingelse also fail……

ProtectedFunction(Duty Pump)

ProtectiveDevice(Standby Pump)

Fails

Failed MultipleFailure


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5. Generic maintenance programs

Old ParadigmGeneric maintenanceprograms can be developed

for most types of physicalassets (similar assets)

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New ParadigmThe Operating Contextdetermines the wayequipment fail, theconsequences of failureand the appropriatemaintenance program

The Operating Context must be clearly defined at the start of the RCManalysis (before maintenance strategy is defined)


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5. Generic maintenance programs

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B A C

Stand alone

Failure of pump A affectsoperations

Try to prevent it from failingPreventive/ Predictive

maintenance)

If pump B fails swi tchto C and repair B

Run to failure

(“BreakdownMaintenance”)

No direct consequences if Cfails while B is still working

Check periodically if C hasfailed (failure finding)

Traditional thinking will suggest a generic maintenance program butthe from the above it is clear that identical items should have

different failure management policies if they are applied differently

Duty Stand-by


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6. Failure history and data

Old ParadigmComprehensive data aboutfailure rates must be

available before it is possibleto develop successfulmaintenance strategies

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New ParadigmIt is more important tounderstand the failuremechanisms andcharacteristics. In ourcontinuous effort toimprove availability andreliability we “destroy”

data required fordeveloping failuremanagement strategies.GOOD

FAIR

POOR


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7. Protective devices

Old ParadigmThe probability of catastrophicfailures can be almost

eliminated by fitting suitableprotection

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New Paradigm Adding protectivedevices only is notenough. A suitablefailure managementstrategy with adequateprotection will reduce the

risk of catastrophes. Adding protection alsoincreases maintenance

Electrical circuitprotection

Standby sump pump


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8. Maintenance Activities

Old ParadigmThere are three basictypes of maintenance:

predictive, preventiveand corrective

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New ParadigmThere are four basic typesof maintenance: predictive,preventive, functionalchecks and correctivemaintenance


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9. Predictive maintenance task frequency

Old ParadigmThe frequency of predictivetasks should be based on the

frequency of the failure and/orthe criticality of the item

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New ParadigmThe frequency ofpredictive task should bebased on the P-FInterval

Maintenance should be worth doing (deal with consequences) andtechnical feasible. Criticality determines weather maintenance is worthdoing, technical characteristics determine the frequency of maintenance.


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9. Predictive maintenance task frequency

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P e r

f o r m a n c e o r

C o n

d i t i o n

( R e s

i s t a n c e

t o S t r e s s )

Time

OK

Point where failure starts to occur(not necessarily related to age)P = Potential Failure(point where we can findout that it is failing)P

•

•

FunctionalFailure

P-F Interval


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10. Formulating maintenance strategies

Old ParadigmMaintenance policies should beformulated by managers andmaintenance schedules drawn up bysuitably qualified specialists orexternal contractors (a top-downapproach)

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New ParadigmMaintenance policies should beformulated by operations andmaintenance personnel workingtogether with anybody else whohave something legitimate to sayabout the asset.

MAINTAINER OPERATOR

SPECIALIST

OPERATIONSSUPERVISOR MAINTENANCESUPERVISOR

FACILITATOR


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Old ParadigmThe maintenance departmenton its own can develop a

successful, lastingmaintenance program

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New ParadigmMaintenance policies shouldbe formulated by operationsand maintenance personnelworking together withanybody else who havesomething legitimate to say

about the asset.MAINTAINER OPERATOR

SPECIALIST

OPERATIONSSUPERVISOR MAINTENANCESUPERVISOR

FACILITATOR


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Old ParadigmEquipment manufacturers are in thebest position to develop maintenanceprograms for new physical assets

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New ParadigmThe expertise of the equipmentmanufacturers should not beignored but in most cases the

OEMs ignore the operatingcontext and will provide genericmaintenance programs. On theirown, the OEMs cannot developsustainable maintenanceprograms……

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