Transcript Quality Control Tools

 Reliability
Centered
Maintenance
 Day II
 Salih O. Duffuaa
Reliability Centered
Maintenance
 Objective of Module
• Present the steps of RCM
• Demonstrate the steps clearly
• At the end each participant should
– Understand the basics of RCM
– Initiate an RCM project
– Participate effectively in teams
implementing RCM.
Impact Of RCM On O&M
Costs
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1984 RCM pilot study At FP & L’s Turkey
Point Nuclear plant provided evidence that
RCM could impact O & M costs
Survey conducted by Electric Power
Research Institute provided more evidence
that RCM has impact on Cost.
RCM Impact
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Plant trip reduction
Documented Basis For PM
Efficient PM Planning
Decrease in corrective maintenance
More accurate spare parts identification
Increase plant availability
Steps of RCM
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System selection and data collection
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System boundary definition
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System description and Functional Block
Diagram
RCM Steps Continued
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Systems function and functional failures
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Failure mode and effect analysis
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Logic tree analysis (LTA)
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Task selection
Level of RCM Application
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Part
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Component---Assembly
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System
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Plant
System Selection and Data
Collection
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Basis of system selection
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What data and information to collect
Criteria for System Selection
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1- Systems with high PM tasks
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2- Systems with high breakdown
maintenance
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3- Systems with large contributions to
full or partial outages.
Criteria for Selection
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4- Systems with high cost of CM actions
 5- Systems with high content of concern with
respect to safety and environmental issues
 6- Combinations of the Above
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In a Typical selection process at Florida Power &
Light Fossil Power Generation 5 is used coupled
with Parato chart.
Information Collection
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System piping and information diagram
System schematic block diagram
Vendor manual
Equipment history file
System operation manual
System design specification and data
description
Importance of system
Boundary Definition
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It provides knowledge of what hs or has not
been included
The boundary determines what comes into
and what leave the system ( in and out)
Boundary definitions must be clearly stated
and documented
Example of system Boundary
Definition
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Refer To Transparencies --- Figure 5.4
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System boundary details --- Figure 5.5 and
Figure 5.6
System Description and
Functional Block Diagram
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System description
Functional block diagram
In/out interfaces
System work breakdown structure
Equipment history
System Description
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Tangible benefit of system description
• Account and document baseline definition of
system as existed
• Ensure comprehensive understanding of the
system
• Aid in identifying critical parameters that
contribute to degradation and loss of function
System Description Cont.
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Elements of System Description
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Functional description/ key parameters
Redundancy features
Protection features
Key instrumentation features
See figure 5.7 in transparences
Functional Block Diagram
(FBD)
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The FBD is a top-level representation of the
major functions the system performs
It consists of functions no equipment
appear. labeled functional subsystems
In/out interfaces shown
See figure 5.8
System Work Breakdown
Structure (SWBS)
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Carryover from Ministry of Defense Terminology
Compilation of the equipment lists in each
functional subsystems shown in the fbd
Include all components within system boundary
list all instrumentation components
See figure 5.10 and 5.11 for equipment history file
Systems Functions and
Functional Failures
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List all functions
In essence every out interface should be
captured into a function statement
Two additional sources for functions
• Internal out interfaces between functional
subsystems
• Passive functions
• List all functional failures
Correct and Not Correct
Function Statements
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Provide 1500 psi safety relief valves(w)
Provide for pressure relief above 1500 psi
Provide a 1500 gpm centrifugal pump on
the discharge side of header 26 (w)
Maintain a flow of 1500 gpm at the outlet of
header 26.
Correct and Not Correct
Function Statements
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Provide alarm to control room if block
valves are < 90 percent open (w)
Provide alarm to control room if flow rate is
< 90 percent of rated flow
Provide water-cooled heat exchanger for
pump lube oil (w)
Maintain lube oil  130 o F.
Functional Failure
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The focus on loss of functions not loss of
equipment
Absolutely necessary to distinguish between
function loss conditions
• Most functions have more than one loss
condition
• Distinction in loss condition usually leads to
different failure modes
Functional Failures
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Function: provide for pressure relief above
1500 psi
Functional failure
• (a) Pressure relief occurs above 1650 psi
• (b) Pressure relief occurs prematurely ( below
1500psi)
Examples of Different
Functional Failure
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Function : Maintain a flow of 1500 gpm at
the outlet of header 26
Functional failures
• (a) Flow exceeds 1500 gpm
• (b) Flow is less than 1500 but greater than 1000
gpm
• ( c ) Flow is less than 1000 gpm
• Function ad functional failure are recorded on
figure 5.12
Failure Mode And Effect
Analysis(FMEA)
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Functional failure and equipment matrix
This matrix address which system
equipment could play a role in the creation
of functional failures. this is done by
completing the matrix in figure 5.13.
Failure Mode and effect
Analysis (FEMA)
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Record The following on figure 5.14
• Component
• Failure Mode --- Figure 5.15 provides typical
description for failure modes
• Failure cause
• Failure effect
• Local
• System
• Plant
Redundancy General Rule
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If redundancy prevent loss of function then
a failure shielded by redundancy should be
given different priority than a failure mode
that can singly defeat a necessary function.
If multiple independent failure in a
redundant situation is possible the we
identified a design issue
Logic Tree analysis (LTA)
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The purpose of this step is further
prioritize failure modes that survive
step 5. the prioritization is done
qualitatively using the logic tree
diagram in figure 5.16 and form 5.17
Task selection
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In this step the appropriate
maintenance task is selected to prevent
the loss of function.
 The task selection road map in figure
5.18 is used for this purpose with form
5.19
Sanity Checklist
The purpose of this check is to review
critically all components failures that
are treated run to failure to see if this
decision is optimal.
 Explain form 5.21
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Terms On Sanity Checklist
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marginal effectiveness : it is not clear that
the rtf costs are significantly less than the
current pm costs
High-cost failure : while there is no loss of
critical function, the failure mode is likely
to cause extensive damage to the
component that should be avoided.
Terms In Sanity Checklist
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Secondary damage: similar to 2, except that
there is a high probability extensive damage
in neighboring components.
OEM conflict : The original manufacturer
recommends a PM task that is not supported
by RCM. It is very sensitive of warranty
conditions are involved.
Terms In sanity Checklist
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Internal conflict : Maintenance or
operation feel strongly about the PM
task that is not supported by RCM.
 Regulatory conflict : regulatory body
established the PM, such as EPA.
 Insurance conflict : similar to the
above two.
Comparison Between RCM
Findings and existing Situation
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RCM-based and current tasks are
identical
 Current PM tasks exist, but need to be
modified to meet RCM-findings.
 RCM-based PM tasks are
recommended where no current tasks
exist.
 Current PM tasks exist where no RCM
tasks-based task recommendedcandidates for deletion