Rcm of compressor

RELIABILITY CENTERED MAINTENANCE OF GAS
COMPRESSOR
CONTACT 03363095695

Karam ali 15me54 (G.L)
Aaqib Hussain 15me08 (A.G.L)
Rashid ali 15me01
Zeeshan 15me151
Nadeem ali 15me56
SUPERVISED BY
ENGR. JAVED REHMAN LARIK

OUTLINES
1. Introduction
i. Presentation Outlines
ii. Project Overview
2. Aims & Objectives
3. Literature Review
i. Reliability Centered Maintenances (RCM)
ii. Failure Mode and Effect Analysis (FMEA)
4. Methodology

OUTLINES (Cont’d)
5. RCM software
i. Survey of RCM Software
ii. Software selection
iii. AvailabilityWorkbench (AWB)
6. Case Study: RCM of Gas Compressor
i. Main Parts of Compressor
ii. FMEA of Compressor (Theoretical Analysis)
iii. Software Based Analysis

PROJECT OVERVIEW
 Maintenance of gas compressor in LPG Plants is difficult task.The difficulties often
arise from the lack of reliable maintenance strategies. RCM addresses this problem
effectively
 In this thesis, Reliability Centered Maintenance (RCM) is done on selected
components of Natural Gas Compressor.
 A comparison is made between different maintenance strategies with reference to
cost & downtime based on FMEA technique of RCM
 The result of FMEA has been validated by using a AvailabilityWorkbench (A RCM
software)
1

PROJECT OVERVIEW (Cont’d)
Some of Common issues of maintenance of Gas compressors are:
1. Impeller BearingWear out
2. ControlValue Failure
3. Vibration issue
4. Air Filter Issue
5. High temperature of lube oil
 In this project first two issues have been studied and a frame work for RCM has been developed
 Based on RCM framework FMEA of Gas Compressor has been conducted theoretically and by using
AvailabilityWorkbench (RCM Software)
2

AIMS & OBJECTIVES
The aim of Project is to conduct FMEA Analysis of gas compressor. To achieve
this aim following objectives were set :
 Identify and Prioritize Failure modes that can affect the compressor function
 To analyze risks in failure of gas compressors
 To make FMEA (Failure modes & effects analysis) of gas compressor using
SEVERITY, OCCURANCE & DETECTION charts.
 To make FMEA of gas compressor using AvailabilityWorkbench Software
 Select applicable and effective tasks to control the failures
3

WHAT IS RCM?
 It is a systematic process and methodology for determining the most effective
and efficient maintenance management plan for a specific platform, system or
component [1]
 It is a corporate level maintenance strategy that is implemented to optimize
the maintenance program of a system [2]
LITERATURE REVIEW
4

WHY RCM IS BETTERTHANTRADITIONAL MAINTENANCE
Traditional Maintenance
 Focused on preserving the operation of the
component
 Consider only schedule maintenance on component
or fix when fail
 Scheduled Maintenance ,if any, based on
manufacturer or vendor recommendation
 More Corrective Maintenance
 Very Reactive approach
Reliability Centered Maintenance
 Focused on preserving the function of the system
 Consider many option, fix when failed only if cost
effective
 Scheduled Maintenance based on the failure
characteristics of the component in its operating
context
 Less Corrective Maintenance
 Proactive Approach
LITERATURE REVIEW
5
[6] [6]

BENEFITS OF RCM
[3]
 Slashing the amount of scheduled preventive maintenance
 Eliminating most Time Between Overhauls (TBOs)
 Reduce downtimes
 Reduce Maintenance Induced Failures (MIFs)
 Reduce overall maintenance cost
 Move to more methodical approach of resource allocation
6

FAILURE MODES & EFFECT ANALYSIS (FMEA)
 The FMEA is a tool used to systematically analyze postulated component
failures and identify the resultant effects on system operations. [4]
 The analysis is sometimes characterized as consisting of two sub-analyses, [5]
 Failure modes and effects analysis (FMEA),
 Failure modes and effects criticality analysis (FMECA).
 Successful development of an FMEA requires that the analyst include all
significant failure modes for each contributing element or part in the system.
 FMEAs can be performed at the system, subsystem, assembly, subassembly or
part level
LITERATURE REVIEW
7

PROCEDURE OF FMEA
Define the System
of Interest
Define the problems
of interest for
analysis
Subdivide the
system for analysis
Identify potential
failure modes
Evaluate potential
failure modes
capable of producing
problems
Performs
quantitative
evaluation
Use the result in
decision making
LITERATURE REVIEW
8

RISK PRIORITY NUMBER (RPN)
[7]
 In FMEA identification and prioritization of failure mode is very important step.
Prioritize of failure mode is based upon RPN.
 RPN is quantitative evaluation of failure mode
 It is calculated for each failure mode by multiplying the numerical ratings of the
severity (S),probability of occurrence (O) and the probability of detection
(D)
RPN=S x O x D
 In general, the failure modes that have the greatest RPN receive priority for
maintenance action
LITERATURE REVIEW
9

SURVEY ON SOFTWARE
 There are different software used for failure analysis, some of them are: [8]
➢ RCM++
➢ Xfmea
➢ IRCM
➢ RBI
➢ n code
➢ AvailabilityWorkbench AWB
 All these software have their own strength & limitations
11

SELECTION OF SOFTWARE
We have selected AvailabilityWorkbench (AWB) software
because :
 It has strong features
 Highly use in industries
 Student License is easily available from vendor
12

AVAILABILITY WORKBENCH
FEATURES
 It integrates FMEA along with RCM
 Does not requires complex and additional knowledge of mathematics
for analysis
 It has different modules in which our concerning modules are two
(02):
 RCMCost
 Weibull
[9]
13

AWB WORKING
 Every software works on some mathematical probability distribution
 Availability WorkbenchWorks onWeibull Distribution
 According to the Weibull Distribution the reliability equation is :
“η” is the point at which 63.2% of population is going to failed state.
14
[10]

THEVALUE OF SHAPE
FACTOR (β) DEPENDS
OF SOME FAILURE
BEHAVIOR
15

AVAILABILITY WORKBENCH RCMCOST MODULE
16

CASE STUDY : RCM OF GAS COMPRESSOR
 In this case study, we have conducted FMEA of gas compressor installed at case study plant
 The compressor under study is 3-stage centrifugal compressor used to compress natural gas
 Following are inlet and discharge conditions of compressor
CONDITIONS INLET DISCHARGE
Pressure ( MPa ) 3.57 8.72
TEMPERATURE ( °C) 44 131
Speed (RPM) 7050
Cp/Cv 1.39 1.35
17
[11]

MAIN PARTS OF COMPRESSOR
 Casing & Internal Cartridge
 Rotor
 Impeller
 Bearing
 Diaphragm
 ControlValve
 Sealing Device
18

FAILURE MODES & EFFECTS ANALYSIS (THEORETICAL ANALYSIS)
Function Functional Failure Failure Mode Failure Effect
Compress Natural Gas from
3.57 MPa to 8.72 MPa
Fails to compress natural gas
at all
Impeller jammed by
foreign object
• GasTurbine Trips due to
overload
Line Shaft Bearing Seize
due to NormalWear &
Tear
• GasTurbine Trips due to
overload
• Supply of Natural Gas
Stops
spurious signal from trip
mechanism
• Compressor Shutdown
Impeller Bearing seize due
to lack of lubrication
• magnetic drag causes
turbine overload
• Overload may cause
system shutdown
19

FAILURE MODES & EFFECTS ANALYSIS (THEORETICAL ANALYSIS)
(Cont’d)
Function Functional Failure Failure Mode Failure Effect
3.57 MPa to 8.72 MPa
Fail to supply enough quantity
(flow rate) of natural gas
Loss of Coolant Capability • the impeller will wear
our due to high
temperature
• vibration will be
produced
clogged discharge port • loss of compressor
output
leakage of output gas back
to low pressure side
• loss of gas capacity
valve sticking • Overheating
• increase wear
• flow loss
Fails to compress natural gas
at required pressure
Accumulation of water in
lubricant
• Early Compressor Failure
20

RISK PRIORITY NUMBER (RPN) CALCULATION
Functional Failure Failure Mode S O D RPN
3.57 MPa to 8.72 Mpa
Impeller jammed by foreign object 10 2 1 20
Line Shaft bearing seizes due to normal wear & tear 9 5 4 180
Bending of shaft during operation 8 2 1 16
Compressor Impeller Wear out 8 4 1 32
Impeller Bearing Seizes due to lack of lubrication 9 1 6 54
Fails to supply enough quantity
(Flow rate) of natural gas
Loss of coolant capability 9 5 1 45
Clogged Discharge Port 5 6 3 90
Leakage of output gas back to low pressure side 3 7 3 63
Valve Sticking 6 7 7 294
Fail to compress natural gas at
required pressure
Accumulation ofWater in Lubricant 4 3 9 108
Severity (S)
Occurrence (O)
Detectability (D)
22

PRIORITIZATION OF FAILURE MODES ON THE BASIS OF RISK
PRIORITY NUMBER (RPN)
S.No. Failure Modes (RPN)
1 ControlValve Failure 294
2 Line Shaft Bearing Seize due to normal wear and tear 180
3 Accumulation of water in lubricant 108
4 Clogged Discharge Port 90
5 Leakage of Output Gas back to low pressure side 63
6 Impeller Bearing Seized due to lack of lubrication 54
7 Loss of coolant capability 45
8 Compressor Impeller Wear-out 32
9 Impeller Jammed by foreign object 20
23

FMEA INTERPRETATION
 We prioritize the Failure modes based on Risk Priority Number (RPN)
 RPN shows the criticality of failure mode
 From above prioritization we noted that control valve failure is relatively most
critical failure than others
 On the basis of RPN number, we select the most appropriate and best maintenance
strategy for each failure
24

SOFTWARE BASED ANALYSIS OF RELIABILITY CENTERED
MAINTENANCE (RCM)
 Software based analysis is done on AvailabilityWorkbench (AWB) using RCMCost
and Weibull Module
 Analysis is made by input of Failure history data or Weibull variables recorded by
industry
 The results of software are in the form of Cost, Criticality, and Downtime
 We have selected two components of compressor for RCM Analysis
 Impeller Bearing
 ControlValve
25

IMPELLER BEARING
Function Reduce Friction,
Avoid loss Power
Functional
Failure
Bearing Seizes
Failure Cause Lack of Lubrication
Failure Effect Compressor
Shutdown
26

COST & DOWN
TIME SIMULATION
ONTHE BASIS OF
BREAKDOWN
MAINTENANACE
27

COST & DOWN
TIME SIMULATION
ONTHE BASIS OF
PLANNED
MAINTENANACE
28

PLANNED
MAINTENANCE
COST &
CRITICALITY
GRAPH
29

COST & DOWN
TIME SIMULATION
ON THE BASIS OF
INSPECTION
30

INSPECTION
MAINTENANCE
COST &
CRITICALITY
GRAPH
31

COST & DOWNTIME
SIMULATION ONTHE
BASIS OF BOTH
PLANNED
MAINTEANCE &
INSPECTION
32

COMPARISION & INTERPERTATION OF RESULTS FOR IMPELLER
BEARING
 It may be noted that based on cost Inspection is
best maintenance strategy
 There is no significant increase of operational
criticality in inspection compared with other
maintenance strategies
 The downtime is lesser in both Combined Planned
& Inspection but the cost is high relative to only
Inspection
 As a result, Inspection is a optimized maintenance
strategy
Maintenance
Strategy
Cost ($) Operation
Criticality (out of
1)
Downtime
(hrs)
Run-to-failure 288900 0.00171 16.16
Planned
Maintenance
304600 0.00097 9.52
Inspection 116300 0.000539 5.25
Combined Planned
& Inspection
225900 0.000417 4.06
33
Table 1

CONTROLVALVE
Function Regulate the
flow
Functional
Failure
Valve Shuts
Unexpectedly
Failure
Cause
Wear over time
Failure
Effect
Compressor
Shutdown
34

COST & DOWNTIME
SIMULATION ONTHE
BASIS OF
BRAKDOWN
MAINTEANCE
35

COST & DOWNTIME
SIMULATION ONTHE
BASIS OF PLANNED
MAINTEANCE:
36

RECOMMENDATION
BASED ON PLANNED
MAINTENANCE
37

COST & DOWN
TIME SIMULATION
ONTHE BASIS OF
INSPECTION
38

COST &
CRITICALITY
GRAPH BASED
ON INSPECTION
39

COST & DOWN TIME
SIMULATION ON THE
BASIS OF BOTH
PLANNED MAINTEANCE
& INSPECTION
40

COMPARISION & INTERPERTATION OF RESULTS FOR CONTROL
VALVE
 From the results, it may be noted that in Run-to-
failure the overall cost is relatively low, but
downtime is very high
 Inspection has relatively much less cost after Run-
to-failure maintenance
 Based on down time, Combined Planned &
Inspection is better but it is not feasible in terms of
cost
 So, for the control valves Inspection is relatively an
optimized maintenance strategy
Maintenance
Strategy
Cost ($) Operation
Criticality (out
of 1)
Downtime
(hrs)
Run-to-failure 123100 0.01227 107.5
Planned
Maintenance
895100 0.0054 47.46
Inspection 277000 0.00136 11.97
Combined
Planned &
Inspection
506000 0.00093 8.187
41
Table 2

FUTURE WORK
 RCM analysis should be done on all components of compressor and
whole plant
 Selection of optimized maintenance strategy for each equipment
 Implementation of selected maintenance strategies on each equipment &
hence the while system
42

REFERENCES
1. Jeff banks,2008 “RCM –an overview of the process” Available At
https://www.acq.osd.mil/log/MR/.rcm.html/RCM_brochure.pdf
2. Smith,Hinchcliffe,2003. “Reliability Centered Maintenance” , Butter-Worth Heinemann, Oxford
3. Atiq Waliullah,2015. “Reliability Centered Maintenance, Book Chapter In Handbook of Maintenance Management &
Engineering(PP397-415), Springer, Berlin
4. John Moubray,1999. “RCM II”, Butter-Worth Heinemann, Oxford
5. Anthony M.D, 2004 “A Statistical Comparison of three root cause analysis tools”. Journal of industrial technology, 20(2)
6. I.V. Sfflshkova, bulgaria,2004 “RCM VS. Traditional maintenance practice — some problems when rcm is introduced
for the first time”. Available at http://www.Iaea.Org/inis/collection/nclcollectionstore/_public/31/022/31022329.Pdf
7. http://www.ihi.org/resources/Pages/Measures/RiskPriorityNumberfromFailureModesandEffectsAnalysis.aspx
8. https://www.weibull.com/
9. https://www.isograph.com/software/availability-workbench/
10. http://reliawiki.org/index.php/The_Weibull_Distribution
11. https://statstuff.com/ssfiles/tools/FMEAScalesGuide.pdf
43

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