AN INVESTIGATION INTO THE SELECTION OF AN OPTIMISED 
MAINTENANCE STRATEGY FOR CONVEYOR SYSTEMS WITHIN THE 
PORT OF RICHARDS BAY 

 

 

 

 

Laventhran Naidoo  

 

 

 

 

 

A Research Project submitted to the Faculty of Engineering and the Built 
Environment in partial fulfilment of the requirements for the degree of 
Master of Science in Mechanical Engineering 

 

 

 

 

 

Johannesburg, 2022  



1 

DECLARATION 
 

University of the Witwatersrand, Johannesburg 

School of Mechanical, Industrial and Aeronautical Engineering 

SENATE PLAGIARISM POLICY 

Declaration by Students 

  

I hereby declare the following: 

• I am aware that plagiarism (the use of someone else’s work without 
their permission and/or without acknowledging the original source) 
is wrong. 

• I confirm that all the work submitted for assessment for the above 
course is my own unaided work except where I have explicitly 
indicated otherwise. 

• I have followed the required conventions in referencing the thoughts 
and ideas of others. 

• I understand that the University of the Witwatersrand may take 
disciplinary action against me if there is a belief that this is not my 
own unaided work or that I have failed to acknowledge the source 
of the ideas or words in my writing. 

  

Signature: _____________________ Date: ______________________ 

 

 

  

  

Laven Naidoo
18/03/2022



2 

ABSTRACT 

This research aimed to use conveyor failure data from the PORB to: 1) 

Review and identify effects of the existing maintenance approach, 2) 

Highlight failure causes and consequences and 3) To determine the most 

suitable maintenance strategy for conveyors in the PORB that will reduce 

failures thereby reducing downtime and loss of revenue. The scope of 

research was narrowed to the routes which had experienced the most 

failures which was supported through use of the Pareto principle. The 

failure data was put through a logical sequence of failure analysis tools to 

identify cause-and-effect relationships and survey questionnaires were 

sent to key personnel which formed the basis for the selection of a 

maintenance strategy. The research has shown that a modified version of 

Reliability Centred Maintenance (RCM), with dominant predictive methods, 

will provide benefit to the business by applying the appropriate 

combination of maintenance strategies (RM, PM or PdM) and prioritising 

maintenance tasks based on the equipment and components that pose 

significant consequential risks. 

  



3 

DEDICATION 

For my dear wife, Kimay Naidoo, for being the pillar of support and 

motivating me through this research process.    

  



4 

ACKNOWLEDGEMENTS 

I would like to sincerely recognise and acknowledge the effort, support and 

guidance from my supervisor, Mr. John Jones, and co-supervisor, 

Professor Vishal Sharma, both from the School of Mechanical, Industrial 

and Aeronautical Engineering at the University of Witwatersrand.  

I would like to thank Transnet SOC for allowing me the opportunity to 

conduct this research in utilising their data and resources. 

  



5 

CONTENTS           Page 

DECLARATION ......................................................................................... 1 

ABSTRACT................................................................................................ 2 

DEDICATION ............................................................................................. 3 

ACKNOWLEDGEMENTS .......................................................................... 4 

LIST OF FIGURES ................................................................................... 10 

LIST OF TABLES .................................................................................... 14 

LIST OF ABBREVIATIONS ..................................................................... 16 

ETHICAL CLEARANCE .......................................................................... 18 

1 CHAPTER 1: BACKGROUND ......................................................... 19 

 Introduction .............................................................................. 19 

 Research Problem.................................................................... 22 

 Motivation ................................................................................. 25 

 Research Aim ........................................................................... 27 

 Critical Research Question ..................................................... 27 

 Research Objectives ................................................................ 28 

 Research Report Overview ..................................................... 28 

2 CHAPTER 2: LITERATURE REVIEW .............................................. 29 

 Introduction .............................................................................. 29 

 Overview of a Conveyor Belt .................................................. 29 

 Reliability and Maintenance .................................................... 34 

 Maintenance Strategies ........................................................... 35 

2.4.1 Reactive Maintenance ............................................................ 36 

2.4.2 Preventive Maintenance ......................................................... 37 

2.4.3 Predictive Maintenance .......................................................... 38 

2.4.4 Reliability Centred Maintenance (RCM) ................................. 39 



6 

2.4.5 Total Productive Maintenance ................................................ 42 

2.4.6 Maintenance Steering Group 3 ............................................... 44 

2.4.7 Maintenance Strategy Selection ............................................. 45 

 Previous studies ...................................................................... 47 

 Research Method Types .......................................................... 51 

2.6.1 Data collection ........................................................................ 55 

2.6.2 Research Validity and Reliability ............................................ 57 

 Analysis tools ........................................................................... 57 

2.7.1 Pareto Principle ...................................................................... 58 

2.7.2 Failure Modes, Effects and Criticality Analysis ....................... 58 

2.7.3 Weibull Analysis ..................................................................... 59 

2.7.4 The Five Whys........................................................................ 60 

2.7.5 Ishikawa Diagram ................................................................... 61 

2.7.6 Multi Criteria Analysis (MCA) .................................................. 62 

 Literature Review Summary .................................................... 63 

3 RESEARCH DESIGN AND METHODS ............................................ 65 

 Research and Data Analysis Method and Overview ............. 65 

 Research Design ...................................................................... 66 

 Data Collection and Analysis Methods .................................. 69 

3.3.1 Data Collection techniques ..................................................... 69 

3.3.2 Level of Analysis..................................................................... 71 

3.3.3 Critical Item Selection ............................................................. 72 

3.3.4 Data Analysis ......................................................................... 73 

 Failure Analysis Tools ............................................................. 75 

3.4.1 Failure Modes, Effects and Criticality Analysis (FMECA) 

Method .............................................................................................. 75 

3.4.2 Weibull Method ....................................................................... 78 

3.4.3 Ishikawa “Fishbone” Method .................................................. 79 

3.4.4 The Five Whys Method ........................................................... 79 



7 

 Research Validity and Limitations .......................................... 80 

3.5.1 Assumptions and Limitations .................................................. 81 

4 RESEARCH CONTEXT .................................................................... 82 

 Boundary Definition ................................................................. 84 

 Conveyor Berth Selection ....................................................... 85 

 Common Failures in Conveyors at the PORB ....................... 86 

4.3.1 Pulleys .................................................................................... 87 

4.3.2 Idler failures ............................................................................ 88 

4.3.3 Electric Motor and Gearbox failures ....................................... 89 

4.3.4 Belting damage....................................................................... 89 

4.3.5 Take-up failures ...................................................................... 93 

 Existing Failure Effects ........................................................... 94 

 Ishikawa Diagram ..................................................................... 94 

4.5.1 People/staff ............................................................................ 96 

4.5.2 Operations .............................................................................. 96 

4.5.3 Environment ........................................................................... 97 

4.5.4 Materials ................................................................................. 97 

4.5.5 Machinery/Equipment ............................................................. 98 

 The Five Whys .......................................................................... 99 

4.6.1 Conveyor drive failure ........................................................... 100 

4.6.2 Belting failure ........................................................................ 101 

4.6.3 Idler Failure .......................................................................... 103 

4.6.4 Pulley failure ......................................................................... 104 

4.6.5 Take-up failure...................................................................... 105 

5 RESULTS PRESENTATION AND DISCUSSION .......................... 107 

 Conveyor Failure Types on Selected Berths ....................... 107 

 Existing Failure Effects ......................................................... 113 

 First Survey Questionnaire Results: General ...................... 121 



8 

 Failure Modes, Effects and Criticality Analysis (FMECA) 
Results ............................................................................................... 123 

5.4.1 FMECA Remedial Actions .................................................... 127 

 Weibull Analysis..................................................................... 130 

 Second Survey Questionnaire Results: MCA ...................... 134 

 Discussion .............................................................................. 140 

5.7.1 Existing Failure Effects ......................................................... 140 

5.7.2 First Survey Questionnaire ................................................... 142 

5.7.3 FMECA ................................................................................. 143 

5.7.4 Weibull .................................................................................. 146 

5.7.5 Second Survey Questionnaire and MCA .............................. 148 

5.7.6 Maintenance Strategy Selection ........................................... 150 

6 CONCLUSION AND RECOMMENDATION ................................... 154 

 Conclusion ............................................................................. 154 

 Recommendations for Future Work ..................................... 157 

REFERENCES ....................................................................................... 159 

APPENDICES ........................................................................................ 172 

A. APPENDIX A: CONVEYOR LAYOUT PORB ................................. 172 

B. APPENDIX B: CONVEYOR FAILURE DATA ................................ 173 

B1 Conveyor failure data received from PORB .............................. 173 

B2 Conveyor failure data per component ....................................... 175 

B3 Planned versus Achieved Tonnages ......................................... 175 

C. APPENDIX C: DETAILED FMECA TABLE .................................... 177 

D. APPENDIX D: WEIBULL RESULTS .............................................. 181 

D1 Speed switch failure.................................................................... 181 

D2 Conveyor unplanned maintenance actions .............................. 183 

D3 Conveyor misalignment.............................................................. 186 



9 

D4 Conveyor bearing or coupling failure........................................ 189 

D5 Conveyor tripped ........................................................................ 191 

D6 Conveyor belting failure ............................................................. 193 

D7 Conveyor drive failure ................................................................ 197 

E. APPENDIX E: FIRST QUESTIONNAIRE ....................................... 204 

F. APPENDIX F: SECOND QUESTIONNAIRE .................................. 205 

 

  



10 

LIST OF FIGURES 

Figure 1.1: PORB Conveyor Layout (3) .................................................... 19 

Figure 1.2: Typical Conveyor within the Port of Richards Bay (PORB) .... 22 

Figure 1.3: Typical PORB wear liners with wear indicators (25) ............... 23 

Figure 1.4: Pulley end disc failure ............................................................ 24 

Figure 1.5: Planned versus Achieved Tonnages per year ........................ 26 

Figure 1.6: Planned versus Achieved Tonnages at the PORB ................. 26 

Figure 1.7: Tonnages vs Failures at PORB .............................................. 27 

Figure 2.1: Conveyor Components (37) ................................................... 30 

Figure 2.2: Troughed Conveyor Cross sectional view (38) ....................... 30 

Figure 2.3: Exploded view of conveyor belting (39) .................................. 31 

Figure 2.4: Transfer chute and material loading (41) ................................ 32 

Figure 2.5: Deflector plates that guide material centrally .......................... 33 

Figure 2.6: Conveyor idler exploded view (43) ......................................... 33 

Figure 2.7: Pillars of TPM (60).................................................................. 43 

Figure 2.8: Flow diagram of MCA process (99) ........................................ 62 

Figure 3.1: Research process flow diagram ............................................. 68 

Figure 3.2: Snapshot of Failure Data ........................................................ 69 

Figure 3.3: Conveyor critical components and failures modes ................. 73 

Figure 3.4: Failure types and commodity in operation .............................. 80 

Figure 4.1: Process flow block diagram of conveyor routes and berths ... 83 

Figure 4.2: Pie Chart showing percentage of failures per area................. 84 

Figure 4.3: Bar Chart showing ranked conveyor route failures ................. 85 

Figure 4.4: Bar Chart showing Planned vs Actual tonnages..................... 86 

Figure 4.5: Pulley end disk failure ............................................................ 87 



11 

Figure 4.6: Spillage and dust ingress resulting in seized pulley bearing .. 88 

Figure 4.7: Idler bearing and end cap failure ............................................ 89 

Figure 4.8: Effects of loading off-centre (41) ............................................ 91 

Figure 4.9: Belt edge buckling under load ................................................ 91 

Figure 4.10: Engineered flow Chute DEM (113) ....................................... 92 

Figure 4.11: Take-up winch failure ........................................................... 93 

Figure 4.12: Conveyor failure fishbone diagram ....................................... 95 

Figure 4.13: Failure types and commodity in operation .......................... 100 

Figure 5.1: Selected berths failure types ................................................ 108 

Figure 5.2: Bar Chart showing percentage of failures on selected routes vs 
other routes ............................................................................................ 109 

Figure 5.3: Bar chart showing no. of failures and type per berth ............ 111 

Figure 5.4: Pie chart showing percentage failure types on selected routes
 ............................................................................................................... 111 

Figure 5.5: Failure types and commodity in operation ............................ 112 

Figure 5.6: Bar Chart showing Planned vs Actual tonnages................... 113 

Figure 5.7: Planned Maintenance Intervals for Conveyor routes ............ 115 

Figure 5.8: Operational schedule showing actual maintenance interval . 115 

Figure 5.9: Bar chart showing failure correlation of planned vs actual 
tonnages for 703 .................................................................................... 117 

Figure 5.10: Bar chart showing failure correlation of planned vs actual 
tonnages for 704 .................................................................................... 118 

Figure 5.11: Snapshot of operational schedule data .............................. 118 

Figure 5.12: Bar chart showing failure correlation of planned vs actual 
tonnages for 801 .................................................................................... 120 

Figure 5.13: Failure correlation of planned vs actual tonnages for all routes
 ............................................................................................................... 121 

Figure 5.14: Survey Questionnaire responses – component maintenance
 ............................................................................................................... 123 



12 

Figure 5.15: Condition monitoring devices for conveyor (116) ............... 127 

Figure 5.16: Weibull Density Function and Regression Data for speed 
switch failure........................................................................................... 133 

Figure 5.17: Weibull distribution for failure and suspension of the conveyor 
speed switch........................................................................................... 134 

Figure 5.18: Bar Chart showing MCA questionnaire results ................... 138 

Figure 5.19: Sensitivity radar graph ........................................................ 139 

Figure D.1: Weibull Density Function and Regression Data for speed 
switch failure........................................................................................... 181 

Figure D.2: Weibull distribution for failure and suspension of the conveyor 
speed switch........................................................................................... 182 

Figure D.3: Weibull Density Function and Regression Data for 
Maintenance actions .............................................................................. 185 

Figure D.4: Weibull distribution for failure and suspension of conveyor 
maintenance ........................................................................................... 185 

Figure D.5: Weibull Density Function and Regression Data for misaligned 
conveyor ................................................................................................. 187 

Figure D.6: Weibull distribution for failure and suspension of the 
misaligned conveyor ............................................................................... 187 

Figure D.7: Weibull Density Function and Regression Data for 
bearing/coupling failure .......................................................................... 189 

Figure D.8: Weibull distribution for failure and suspension of the conveyor 
bearing/coupling ..................................................................................... 190 

Figure D.9: Weibull Density Function and Regression Data for tripped 
conveyor ................................................................................................. 192 

Figure D.10: Weibull distribution for failure and suspension of a tripped 
conveyor ................................................................................................. 192 

Figure D.11: Weibull Density Function and Regression Data for belting 
failure ..................................................................................................... 196 

Figure D.12: Weibull distribution for failure and suspension of the conveyor 
belting ..................................................................................................... 196 



13 

Figure D.13: Weibull Density Function and Regression Data for drive 
failure ..................................................................................................... 198 

Figure D.14: Weibull distribution for failure and suspension of the conveyor 
drive ....................................................................................................... 199 

Figure D.15: Weibull Density Function and Regression Data for idler failure
 ............................................................................................................... 201 

Figure D.16: Weibull distribution for failure and suspension of the conveyor 
idlers ....................................................................................................... 202 

 

  



14 

LIST OF TABLES 

Table 2.1: Comparison of Qualitative and Quantitative Research Methods 
(87) ........................................................................................................... 54 

Table 3.1: Severity ranking used in FMECA (26) ..................................... 76 

Table 3.2: Occurrence ranking used in FMECA (26) ................................ 77 

Table 3.3: Detection probability ranking used in FMECA (26) .................. 77 

Table 4.1: Five Whys – Conveyor drive failure ....................................... 101 

Table 4.2: Five Whys - Belting failure ..................................................... 102 

Table 4.3: Five Whys - Idler failure ......................................................... 104 

Table 4.4: Five Whys - Pulley failure ...................................................... 105 

Table 4.5: Five Whys - Take-up failure ................................................... 106 

Table 5.1: Failure type split on selected berths ...................................... 110 

Table 5.2: Simplified failure modes, effects and criticality analysis table 125 

Table 5.3: Remedial actions on simplified FMECA table ........................ 128 

Table 5.4: Weibull results summary ....................................................... 131 

Table 5.5: Speed switch failure data in Weibull Analysis ........................ 132 

Table 5.6: MCA results received on questionnaire two .......................... 136 

Table 5.7: Summarised MCA results ...................................................... 137 

Table 5.8: Sensitivity Analysis of MCA scoring....................................... 139 

Table B.1: Filtered Conveyor failure Data .............................................. 175 

Table B.2: Summarised Planned vs Actual tonnages for selected berths
 ............................................................................................................... 175 

Table D.1: Speed switch failure data in Weibull Analysis ....................... 181 

Table D.2: Unplanned maintenance data in Weibull Analysis ................ 183 

Table D.3: Misalignment failure data in Weibull Analysis ....................... 186 

Table D.4: Bearing/Coupling failure data in Weibull Analysis ................. 189 



15 

Table D.5: Conveyor tripped data in Weibull Analysis ............................ 191 

Table D.6: Belting failure data in Weibull Analysis ................................. 193 

Table D.7: Drive failure data in Weibull Analysis .................................... 197 

Table D.8: Idler failure data in Weibull Analysis ..................................... 200 

  



16 

LIST OF ABBREVIATIONS 

CAPEX - Capital Expenditure 

CBM  - Condition-based preventive maintenance 

FFOP  - Failure free operating period 

FMEA  - Failure modes and effects analysis 

FMECA - Failure modes, effects, and criticality analysis 

KZN  - Kwa-Zulu Natal 

MCA  - Multi Criteria Analysis 

MCDM - Multi Criteria Decision Making 

MFOP  - Maintenance free operating period 

MSG 3 - Maintenance Steering Group 3 

MTBF  - Mean time between failures 

Mtpa  - Million tonnes per annum 

MTTF  - Mean time to failure 

MTTR  - Mean time to repair 

PM  - Preventive maintenance 

PORB  - Port of Richards Bay 

RCM  - Reliability Centred Maintenance 

RTF  - Run-to-failure 

S&F  - Search and Find 

SRCM  - Streamlined Reliability Centred Maintenance 



17 

TPH  - Tonnes per hour 

TPM  - Total Productive Maintenance 

WW2  - World War Two 

  



18 

ETHICAL CLEARANCE 

A memorandum and agreement have been signed by the relevant 

authorities to allow the transfer and use of data by the author for this 

research project. A non-disclosure agreement has also been signed by the 

author in obtaining and protecting the information and its use for this sole 

research report and publication. Ethics Clearance as per protocol number 

MIAEC 105/20 has been granted.  

 

 



19 

1 CHAPTER 1: BACKGROUND 
 Introduction 

Bulk materials handling (BMH) operations perform a critical role in a great 

number and variety of industries worldwide, including South Africa (1). The 

Port of Richards Bay (PORB), located in the North of Kwa-Zulu Natal 

(KZN), is considered one of the largest export ports in Southern Africa 

when considering volumes handled (2). A network of conveyors within the 

port terminal, with the PORB conveyor layout shown in Figure 1.1 and the 

full network shown in APPENDIX A: CONVEYOR LAYOUT PORB, are the 

means of transporting bulk cargoes for storage, export and import (3). The 

port is currently a multiple cargo handling port conveying a variety of 

mineral bulk cargo with varying material characteristics (4). The conveyors 

were pre-dominantly designed and built between the 1970’s and 1980’s to 

operate for woodchips and subsequently coal with a design life of 25 years 

(5).  

 

Figure 1.1: PORB Conveyor Layout (3) 

 



20 

The port has noted that the number of conveyor failures have increased 

within recent years and require frequent unplanned maintenance to ensure 

their operation (6).  

Maintenance is the practice used to ensure equipment performance meets 

the end users’ expectations, in the case of this research, conveyor 

equipment performance (7). Maintenance of machinery and equipment 

has been needed ever since the development of machinery and 

equipment (8). The requirement of maintenance, and the management 

thereof, was triggered by the advancement in machinery, technology and 

complexity of equipment, systems and processes together with the 

advancement in specialist maintenance required for these pieces of 

equipment, e.g. vibration and oil analysis on lubricated components (8). 

The importance of regular maintenance on a conveyor system is largely 

second to that of revenue and profit, but consistent maintenance is an 

irrefutable approach to prolong the operating period of any conveyor and 

associated components which in turn can ensure steady operations and 

income generation (9,10).  

Routine maintenance should ensure that the conveyor belt and associated 

infrastructure such as the idlers, chutes, pulleys, etc. remain in a useful 

operating condition adequate to ensure successful operation whilst 

disregarding maintenance activities will undeniably lead to damages and 

expenses that could have been avoided (9). Potential and existing 

difficulties which can increase downtime and maintenance costs can be  

detected through the conduct of routine maintenance. In addition to 

detecting impending issues, routine maintenance can also provide 

maintenance and technical staff with the prospect of identifying areas that 

can be improved to streamline operations. This leads to the importance of 

any plant or operation following a maintenance strategy and plan (11).  

A maintenance strategy is a systematic approach to ensure facilities, 

equipment and components are operational. It involves the identification of 

an approach and plan to inspection, repairs and replacement specific to 



21 

the operation, equipment and its components. It further involves the 

integration with other facets of the business such as planning and finance 

to ensure optimal usage of the plant (12). Maintenance plays a crucial role 

in achieving any organisation’s goals and objectives with finding a balance 

between the maintenance cost and maximising production (13,14). The 

selection of an incorrect maintenance strategy can lead to improper 

maintenance activities being carried out on equipment which can pose 

serious risk to the safety of personnel and the operation, which directly 

impacts revenue (14). Improper maintenance activities could also reduce 

the life of machinery, equipment and components as they could be 

damaged or not adequately serviced or maintained through incorrect 

maintenance practices (15,16). Poor maintenance quality can dramatically 

decrease the reliability of equipment and may cause equipment to move 

towards a critical state and in many cases be operated to failure (17).  

Optimised maintenance strategies provide organisations with various 

opportunities and challenges in the effort of improving performance 

through reduced failures and improved reliability (18). A structured 

maintenance approach and strategy plays an important role in the efficient 

running of a plant, particularly in the BMH environment where, roughly put, 

operational uptime of the plant directly equates to revenue. In the 

conveyor belt industry there are drastic consequences to failure ranging 

from downtime and the associated costs, to loss of life (19). With the 

evolution of maintenance, it has become critical to ensure alignment 

between business strategies and maintenance strategies (13,16). 

Therefore, maintenance optimisation through detailed planning of various 

maintenance actions provide an area of opportunity for improvement (18).  

BMH industries generally adopt the traditional preventive maintenance 

(PM) strategy and techniques that utilise visual periodic inspection based 

on the expertise and experience of the maintenance staff (20). The 

dominant maintenance strategy within the PORB is that of inspection-

based maintenance relying on the visual inspection skills of staff to 



22 

determine when repairs or replacement of components or equipment are 

to occur (21).  

 Research Problem 

The reliability of conveyor belts has always been of major concern within 

the BMH industry (22). The conveyor route reliability can be deemed as an 

integrated reliability of its components i.e. belt, pulleys, drive unit and idler 

rolls etc. (23). Figure 1.2 shows two typical conveyors within the PORB. 

 

 

 

 

 

 

Figure 1.2: Typical Conveyor within the Port of Richards Bay (PORB) 

 

The Existing Maintenance Strategy in the PORB utilises a system where 

the conveying routes are electrically interlocked and controlled to prevent 

product spillage under fault conditions. The port adopts a visual-based 

preventive approach, which they refer to as a Search-and-Find-principle, 

with the maintenance actions as listed below (21):  

• The conveyors and their surrounds shall be kept clean at all times. 

Product spillages, accumulation of grease and other contaminants 

on the structural parts and walkways shall be immediately removed 

(24). 



23 

• Regular inspection of components and reporting as per 

maintenance plan (bi-annually), 

• Lubrication at regular intervals, which involves greasing of 

components and filling of oil. In the case of abnormal noise or 

vibration, the drive shall immediately be stopped and the cause 

investigated and rectified (24). 

• Adjustments to components such as scrapers, belt tracking devices, 

torqued bolts,  

• Component change out on items such as silica gel moisture 

absorbers, idlers, redundant obsolete technology and equipment.  

The existing maintenance strategy does not eliminate the failures, but it 

adopts a fault-finding approach to determine the cause of an occurrence 

through inspections. This is the least capital-intensive strategy, other than 

run-to-failure, with some sort of structure in ensuring operational uptime of 

the conveyors. It is heavily reliant on a substantial workforce with 

experience and knowledge in identifying worn components or parts as well 

as imminent failures. An example of this condition-based maintenance 

approach through visual inspection is seen on items such as wear liners 

used on hoppers and chutes, where the liners consist of a wear indicator, 

as shown in Figure 1.3, which changes colour to show the remaining 

product life. The existing maintenance approach can also result in failures, 

as can be seen in Figure 1.4, which shows an example of a pulley failure. 

 

Figure 1.3: Typical PORB wear liners with wear indicators (25) 

Wear Liner 
Wear Indicator 



24 

 

Figure 1.4: Pulley end disc failure 

 

As discussed earlier, the PORB has experienced an increase in route 

congestion and failures over the past five years (6). The conveyors were 

pre-dominantly designed and built between the 1970’s and 1980’s to 

operate for woodchips and subsequently coal with a design life of 25 years 

(5). As a result, the BMH equipment has entered the maintenance 

intensive phase of its lifecycle and with Capital Expenditure (CAPEX) lean 

initiatives taken by the organisation to minimise costs, operational staff are 

managing the asset instead of end of life asset replacement. These 

initiatives aim at reducing already low maintenance budgets which in turn 

affects the reliability of the system. While investment in new infrastructure 

is vital in the long term, the need to review current maintenance strategies 

is critical to ensure system availability and uptime of operations (10).  

The lifecycle of equipment or components generally trend to operate for a 

period of time before experiencing a decline of its operating capability that 

occurs toward the end of its useful life (26). The lifecycle of the equipment 

together with the introduction of difficult to handle cargoes such as 

magnetite and chrome ore have introduced new parameters that have not 

been accounted for in the maintenance procedures and intervals, which 

ultimately impacts the overall performance of the conveyor system.  

End Disk Failure 



25 

This research project focuses on the conveyor systems in the PORB, its 

failures and the maintenance approaches adopted in order to investigate 

the selection of an optimised maintenance strategy for the conveyor 

systems at PORB and provide recommendations on implementing it. The 

use of PM cannot blindly be assumed to prevent failures and even if 

failures are prevented, it cannot be assumed that PM will provide the 

required results from the maintenance actions (20). Similar studies in 

analysing exiting maintenance strategies in order to select the most suited 

maintenance approach to conveyors were also conducted previously 

(14,27–30). 

 Motivation 

A stoppage in a conveyor belt route means no production in bulk 

conveying applications resulting in a loss of revenue and an increase in 

maintenance and labour costs (31). On multiple conveyor routes the port 

was unable to perform at its installed capacity levels due to the unreliability 

of the equipment (32). On a single berth it was established that a 

throughput of 2.5 mtpa was achieved versus the installed capacity of 4.5 

mtpa (32). Figure 1.5 shows the variations in planned tonnages versus the 

actual achieved tonnages for the period of December 2018 to May 2020. 

For the month of December 2018 it can be seen that the port obtained 

12% of its planned target. In comparison, for the year of 2019 the port had 

achieved only 30% of its planned target whereas for the period in 2020, it 

can be seen that the port has achieved 27% of its planned volume target. 

This averages to an approximate 22% achieved of the planned targets, as 

shown in Figure 1.6, for the period of data obtained. These charts point to 

the dismal performance of the conveyors in the port.  



26 

 

Figure 1.5: Planned versus Achieved Tonnages per year 

 

Figure 1.6: Planned versus Achieved Tonnages at the PORB 

 

The specific failures and planned and achieved tonnages for each year 

and period are combined as shown on Figure 1.7. The number of failures 

experienced for the period of data obtained, December 2018 to May 2020, 

was 174 failures for all routes averaging approximately 11 failures per 

month. This represents an approximate 50% downtime per each month 



27 

which, considering the port utilises on average 240 days per year for 

operations, equates to roughly 10 days a month downtime.   

 

Figure 1.7: Tonnages vs Failures at PORB 

 

 Research Aim 

The aim of the study is to investigate existing maintenance strategies 

applied to conveyor systems at the PORB and evaluate them against 

other maintenance strategies available in the literature. Conveyor failure 

data and maintenance plans will be gathered, analysed and compared to 

literature with the outcome of recommending an applicable and best suited 

maintenance strategy or strategies for conveyor systems within the PORB. 

 Critical Research Question 

The conveyor failures experienced within the PORB leads to the following 

critical research question: 

What is the most suitable maintenance strategy/strategies that can 
be applied to conveyor belt systems in the PORB?  



28 

 Research Objectives 

The overall objective of this study is to analyse and determine the most 

suitable maintenance strategy, principles and procedures that can be 

applied to conveyor systems in the PORB. 

The specific objectives of this research study are to: 

a. Identify, examine and analyse the existing maintenance strategies 

within the port and its impact on the business 

b. Identify whether a new maintenance strategy/strategies or a change 

in maintenance approach is needed at the PORB 

c. Identify possible new strategies and compare them against the 

current strategy 

d. Provide recommendations on the most suitable maintenance 

strategy/strategies for the conveyors in the PORB. 

 Research Report Overview 

Chapter Two encompasses literature on conveyor belts and its 

components, the principles of reliability and maintenance, the types of 

maintenance and optimised maintenance strategies, failure analysis 

techniques and tools and the varying research methods that can be 

applied to the project. The chapter concludes by selecting a research 

method that will be applied in this project. Chapter Three focuses on the 

detail of the research method and data analysis procedures and tools with 

Chapter Four representing the research context of the project highlighting 

routes for analysis. The results from the data and failure analysis 

procedures and tools utilised is covered in Chapter Five whilst Chapter Six 

concludes with a discussion, summary of the conclusions and 

recommendations based on selecting the most suitable maintenance 

strategy for conveyor systems in the PORB as well as any future work.  

  



29 

2 CHAPTER 2: LITERATURE REVIEW 
 Introduction 

Conveyors are used in numerous applications, with belt conveyors 

particularly utilised to transport material commodity (33). The scale and 

nature of transporting materials and cargo may differ from one industry to 

the next, but the expenses involved in storing and conveying these 

materials and cargo are substantial (33). Thus the design, construction 

and execution of material conveying operations must be approached with 

the objective of achieving maximum productivity with minimal breakdowns 

(1). This literature review attempts to give an understanding on the 

maintenance involved in conveyor belts within the PORB and the general 

practice in the BMH field. It will cover literature on conveyors and their 

components, the maintenance strategies that exist and are applicable to 

conveyor systems, as well as maintenance and reliability procedures used 

to analyse failures of a system and components. It also entails literature 

on previous studies that aimed to select maintenance strategies for 

processing and manufacturing plants that utilise conveyor belt systems 

within their industry. It also covers multi-criteria decision making 

techniques in order to determine the go forward strategy or strategies for 

the plant. It will further explore the reliability and maintenance review 

processes used to analyse failures and identify relationships or patterns 

experienced with failures.  

 Overview of a Conveyor Belt 

An overview of a conveyor’s components is shown in Figure 2.1 and 

Figure 2.2. Troughed conveyors, as utilised in the PORB, are conveyors 

that form an angle to the horizontal to create a troughed shape in order to 

successfully convey its contents without spillage, with a cross sectional 

view shown in Figure 2.2 (34). It comprises a rubber belt, as shown in 

Figure 2.3, joined by means of a splice to become endless and is 

appended through a series of pulleys with a sequence of idler rollers 



30 

equally spaced to support the belting along the conveyors length (35). The 

type of belt used in the conveyor system is dependent on the material 

conveyed, system tensions, desired loading capacity and the operating 

conditions and environment (36). The belt is driven via one of the pulleys, 

referred to as the drive pulley, which is connected to the drive system via a 

coupling (36). The tension within the system is sustained through the use 

of a take-up system, generally attached to the tail pulley, which comprises 

of a counterweight designed to maintain system tension (35). This is 

similar to the conveyors in the port.  

 

Figure 2.1: Conveyor Components (37) 

 

 

Figure 2.2: Troughed Conveyor Cross sectional view (38) 



31 

 

Figure 2.3: Exploded view of conveyor belting (39) 

 

The conveyor systems in the PORB are operated from a central control 

room (CCR) which consists of a number of interlocks that run a series of 

conveyors to form a route to its final offload point. Conveyor systems and 

their equipment generally have a lifespan of between 10 to 15 years 

dependent on the operating conditions, maintenance efficacy and cargoes 

handled (35).  

The rear of a conveyor is referred to as the tail-end and its front end is 

known as the head-end (40). The material is transferred onto a conveyor 

belt close to the tail-end with the actual feed referred to as the loading or 

feed point. The material is discharged at the head end of the conveyor 

onto receiving conveyors via a discharge chute which is referred to as the 

discharge or transfer point as depicted in Figure 2.4 (35). This is the 

process of material transfer that occurs in the port.  



32 

 

Figure 2.4: Transfer chute and material loading (41) 

 

Impact loading is a frequent occurrence in the material handling industry 

due to the nature of the design and transfer chute arrangements, which 

does result in increased wear and could lead to possible failures in the 

critical conveyor components (42). Impact idlers are located at the loading 

point to provide additional support against the impact of the material whilst 

carry idlers support the belt and load along the length of the conveyor on 

the carrying side of the belt (35). Deflector plates are also found at the 

loading point and are used to guide the material centrally on the belt as 

shown in Figure 2.5 (34). The port utilises both impact idlers as well as the 

deflector plates to control loading impact and direct material flow 

respectively.  

Tail pulley 

Loading or feed 
point 

Head pulley 



33 

 

Figure 2.5: Deflector plates that guide material centrally 

 

Once the cargo is discharged from the carrying side of the belt, the return 

belt, which is free of material, is steered toward the tail pulley on the return 

idlers (36,40). The return idlers are on the underside of the belt to support 

the load of the empty belt along the length of the conveyor (36,40). An 

exploded view of an idler is shown in Figure 2.6.  

 

Figure 2.6: Conveyor idler exploded view (43) 

 

Deflector plate 
and movement 



34 

The port also makes use of a chain conveyor on import routes from berth 

609 for commodities such as pet-coke and alumina. The simplest chain 

conveyor system uses a single endless chain to carry cargo from the 

vessel to clients external to the port (44). Sprockets power the chain, 

unlike rollers, which are used with belt conveyors (44).  

 Reliability and Maintenance 

Reliability can be defined as the probability that a process, function or 

system will run for a defined operating period under a defined environment 

(26). Maintainability can be described as the probability that a process, 

function or system can be restored in a given time and environment after 

failure (26). In this context, the conveyor components should operate for 

their specified design life under their specified operating conditions without 

breakdown.  

Reliability is frequently measured by the mean time between failures 

(MTBF), the mean time to failure (MTTF) and the maintenance free 

operating period (MFOP) of a process, function or system (26) whilst 

maintainability is measured by the mean time to repair (MTTR) or restore 

the system, process or function to its original state (45). Complex systems 

generally tend to have in-built reliability (26). The reliability of the system 

can be reduced if maintenance planning and activities are not given equal 

importance as the design (11). Increasing intervals and maintenance tasks 

could also increase failures as a result of incorrect maintenance or 

excessive maintenance resulting in the equipment reliance on frequent 

maintenance (11). The principle rule with regard to maintenance is “Know 

your plant and keep it good as new” (26).  

The beginning and end of correct conveyor maintenance is good 

housekeeping. This does not mean cleaning up the roads and conveyor 

pathways monthly or every second month. It means maintaining a clean 

conveyor system and route at all times through regular inspections 

scheduled periodically. The maintenance team on the conveyor system 



35 

must be made responsible for conducting swift site inspections and 

investigations to detect dangerous conditions. All emergencies should be 

reported immediately so that the conveyor can be locked out and repaired. 

Improper maintenance may result in conveyor fires. Good maintenance is 

necessary not only from the standpoint of reducing breakdowns, but also 

from the standpoint of safety and continuity of operation (46). 

 Maintenance Strategies 

Maintenance is the practice used to ensure equipment performance meets 

the end users’ expectations, in the case of this research, conveyor 

equipment performance (7). A strategy is something that reflects the 

organisations ideals and concepts highlighting the pathway to achieving its 

long term goals and objectives (13,47). It is often found that strategies are 

formulated at a senior management level and when filtered down the 

hierarchical ladder, provides an abstract view of the strategic goal (48).   

Maintenance strategies are a means for transforming business priorities 

and goals into maintenance policies. By addressing existing flaws or 

impending gaps in maintenance activities, a maintenance strategy and 

plan can be developed. The relationship between maintenance and 

business strategies are required to be coherent, unifying and integrated in 

order to ensure a successful operation of the plant and to generate 

revenue (48). There are various maintenance strategies that can be 

applied to plant and machinery to achieve the optimal reliability and 

availability (45). Higher availability comes from building stronger 

components with longer MTTF, ease of operation with shorter MTTR and 

having fewer components that can fail (45).  

Different types of machinery and equipment demand different approaches 

and methods to maintenance, and by distinguishing between the right 

maintenance activities to use, the maintenance and operations personnel 

are able to select or develop the most suitable maintenance strategies to 

use for different type of machinery and equipment (49).  



36 

There are six different maintenance strategies that can be applied in any 

manufacturing concern, namely (11,13,15,50–52): 

1. Reactive Maintenance  

2. Preventive Maintenance (PM) 

3. Predictive Maintenance  (PdM) 

4. Reliability Centred Maintenance (RCM) 

5. Total Productive Maintenance  (TPM) 

6. Maintenance Steering Group 3 (MSG 3) 

 

These six strategies will be discussed in the proceeding sections. As 

described earlier, the port utilised the preventive maintenance which they 

term as the search-and-find principle (S&F). 

2.4.1 Reactive Maintenance 

Reactive maintenance can be described as maintenance that occurs only 

once a failure has occurred (50). This is also known as run-to-failure (RTF) 

or corrective maintenance (53). Reactive Maintenance is fundamentally 

the base from which all preventive maintenance strategies have been 

developed (50). Reactive strategies have several risks and can lead to 

expensive maintenance due to subsequent failures that may result from a 

single component failing (50). The result could further lead to longer 

duration of downtime depending on the spares holding capacity of the 

company concerned which can result in higher operational costs, 

increased standing time and no movement of commodity which can result 

in a loss of revenue, reputational damage and penalties to the company 

from their clients (50). Reactive strategies are suitable for applications 

where the consequences of failure are low to non-existent and the costs 

associated with implementing this strategy outweigh the costs of the 

consequences of the failure (50,54). In the Researchers view this seems 

to be the approach at the port with maintenance activities or schedules not 

being followed. This will be elaborated further in the report.  



37 

2.4.2 Preventive Maintenance 

Preventive maintenance (PM) undertakes maintenance actions prior to 

any failures in order to prevent them from occurring (50). Maintenance 

actions in accordance to pre-determined frequency and schedule to 

replace or repair any components, irrespective of their condition, can be 

classified as time-based PM (50). PM was founded in arms organisations 

during the WW2 period with the original premise focusing on component 

age and replacement after a specific time period (53). Conveyor belts are 

dependent on various different components, with the majority of them 

being serviceable (26). The serviceability of these parts is defined by the 

usage of the component since new or since repaired. The principle of 

infant mortality characterises how this philosophy can be flawed (50). New 

conveyor components (belting, pulleys, idlers, bearings, etc.) are 

susceptible to early-life failure due to installation errors or supplier quality 

and the replacement of this new component will not necessarily improve 

the reliability of the conveyor system or reduce functional failures (50). 

Infant mortality, as a result of installation errors, can be rectified with a 

maintenance team performing assessments and safety checks on the 

works conducted to ensure that the installations are correct (26,50). 

Quality issues from the supplier would require management intervention in 

the appointment of suppliers and development of the specification 

documents (26). 

PM that considers the actual condition of the equipment or component 

through visual assessment and inspection in order to determine the 

required maintenance action is referred to as condition-based preventive 

maintenance (CBM) (19). CBM points to maintenance actions required on 

equipment or components that show signs of imminent failure or 

deterioration in performance characteristics failure (19). CBM aims to 

identify imminent failures so that the required maintenance actions can be 

implemented proactively and not prematurely or post failure (19). This 

method relies on experienced personnel with a background and 



38 

knowledge in spotting imminent failures (19,52). For this approach, 

conveyor components or equipment (idlers, pulleys, belting, etc.) must be 

able to display distinct wear characteristics that would allow the 

maintenance team to predict when the equipment or component would fail 

or be worn out (50). Although this is an improvement on the reactive or 

RTF approach, CBM cannot promise enhanced improvements in uptime 

and reliability as components and equipment wear in an unpredictable way 

(50). It is however important to note that during any visual assessment or 

inspection, naturally other imminent or active problems or issues can be 

identified and resolved prior to any breakdowns and hence, reliability can 

somewhat be improved (50). As described earlier, the port utilised the 

preventive maintenance which they term as the search-and-find principle 

(S&F). 

2.4.3 Predictive Maintenance 

Predictive maintenance (PdM) aims to reduce failures and the consequent 

impact to operations whilst also factoring in scheduled maintenance (50) 

through the use of measurements and tools that detect and monitor 

equipment and components for any sign of wear that could lead to failures, 

thus eliminating the underlying possibility of failure (53). 

Many types of components use sensors to monitor and capture live data 

relating to the condition of the equipment (19). This data can be analysed 

to evaluate the serviceability and predict potential future failures based on 

the previous failure data recorded. This, proves the basis of predictive 

maintenance (26). The quality and accuracy of the data used with the 

predictive maintenance approach is crucial to ensure the effectiveness of 

this strategy (50).  

Predictive maintenance is a stringent inspection and monitoring regime 

that does not include the act of physically monitoring equipment as is the 

case in preventive maintenance. Examples of predictive maintenance are 

(50): 



39 

• Vibration analysis 

• Infrared Thermography 

• Oil analysis 

• Visual inspections 

• Belt thickness monitoring 

PdM differs to PM through its use of monitoring equipment to measure the 

actual deterioration and wear of a component to determine the required 

maintenance actions, whilst PM utilises a pre-determined schedule to 

conduct inspections and maintenance (50). PdM proves a quantifiable 

method to determine the required maintenance actions based on the 

actual condition of the component or equipment, and with an efficient and 

well-coordinated plan it can theoretically reduce significant failures and 

downtime (50). The port make use of this approach on drives solely with 

temperature monitoring devices. The existing strategies and operating 

procedures will be compared to the strategies discussed in this literature 

review in order to identify similarities, issues and possible amendments 

that can ensure its suitability to conveyor belts. 

2.4.4 Reliability Centred Maintenance (RCM) 

Reliability Centred Maintenance (RCM) is a systematic process that 

separates out equipment components of a plant that will respond to some 

sort of scheduled maintenance action from components that will not (26). 

The scheduled maintenance according to (8,26) can be divided into three 

categories: schedule inspection, schedule rework and scheduled 

replacement. If an item does not respond to one of these three 

approaches, there are two options left: run to failure or redesign. Redesign 

often means replacing the item with a part that will respond to scheduled 

maintenance (26).  

For schedule maintenance to work, the following five conditions must 

apply (26):  



40 

1. The failure rate must be increasing which will be investigated during 

the failure analyses 

2. The total cost to replace before failure must be less than the total 

cost to replace after failure, meaning run to failure must not be more 

cost effective. In total cost, we must include labour, materials, and 

outage costs.  

3. The failure rate after replacement must be lower than the failure 

rate before replacement meaning the maintenance activities must 

not have a negative effect on the system 

4. One must be able to predict, at least approximately, when failure is 

likely to occur. This requires accurate data recording of past failures 

5. The maintenance or replacement operation must not induce failures 

 

There are several forms and variations of RCM such as RCM II and 

Streamlined Reliability Centred Maintenance (SRCM). RCM II is a form of 

RCM developed by John Moubray (7). It addresses environmental 

concerns by including a question on possible environmental damage. The 

wording is also simplified when compared to the RCM process. SRCM 

was developed by the electrical power research institute for analysis of 

electrical transmission and distribution systems (26). 

The key focus of the RCM process is to ensure optimal uptime and 

operability of the equipment and components by identify modes of failure 

specific to each component before prioritising those failure modes through 

a ranking analysis (7). Preventive actions are then taken based on the 

ranking of the failure modes which identifies possible risk of safety and 

health related consequential failures or failures hidden to operators (7). 

RCM considers the individual component together with its desired life and 

operational environment (7,55). The RCM process provides the end user 

with a maintenance plan that highlights scheduled maintenance and 

failure-finding tasks for all components within the system (7,55). 

The RCM process includes the following steps (26,56):  



41 

1. Description and selection of equipment and components to probe 

focusing on critical components 

2. Describing the functions each component performs 

3. Preparing a failure modes and effects analysis (FMEA) for each 

component and identifying failures of each 

4. Performing the RCM for each failure using a decision diagram 

5. Determining the remedial maintenance action required 

 

The RCM process, in some instances, as stated by Moubray (7), can 

incorporate a further two questions, namely; “What can be done to predict 

or prevent each failure?”, and “What should be done if a suitable proactive 

task cannot be found?”  

RCM differs from PM or CBM approaches by focusing on the condition of 

an item and attributing maintenance actions based on that actual condition 

(57). The approach further distinguishes between the various function 

failures that exist and its detection probability (57). RCM also considers 

potential hidden and consequential failures that could arise and aims to 

avert it (57). This approach of identifying the consequences allows the 

maintenance actions to be tailored to the specific components and its 

functional failures experienced (7). The principle of RCM allows it to be 

adapted to a variety of failure modes and types that consider the 

operational and process based environment (58). 

RCM can be considered to have been widely used for numerous years 

and is frequently found in maintenance programmes and plans in order to 

improve the operational uptime and reduce failures in organisations. The 

challenges of RCM are that many management executives believe that 

RCM will resolve all problems and the equipment will instinctively improve 

reliability, which is not the case (58). In some cases, an RCM analysis may 

not be the best fit in that the environment and efficient operation could call 

for a single maintenance strategy (58). In other instances, RCM cannot be 

enforced in its full theoretical form, but adaptations or modified forms can 



42 

ensure the main aim of any maintenance strategy, which is to keep the 

equipment running with optimal maintenance costs and time. This 

modified approach typically costs less and may show more benefits for 

organisations (58). 

2.4.5 Total Productive Maintenance  

Total Productive Maintenance (TPM) is a strategy that considers and 

utilises human resources in its approach. TPM’s focus is set on the staff 

and improving their capability and skillset required to conduct their roles 

which is believed to ultimately improve the overall quality of work 

produced. TPM is considered to have been developed within the 

Japanese process industry with factories that utilise assembly lines 

(7,26,55,59). TPM aims to grow productivity by investing in applicable 

maintenance to reduce losses (60). 

TPM’s centric is to ensure the resources are well equipped and trained 

within the overall production process with the intention of creating a failure 

free environment (16). The aims of TPM are to maximise equipment 

effectiveness, optimise the maintenance system to achieve this, make 

sure the entire company is involved and to make sure that all employees 

are involved, by developing autonomous small group activities (26,61). 

The strategy requires involvement from top management to ground staff. 

This type of involvement tends to be time-consuming, expensive and is 

often met with resistance from operational and maintenance employees 

(26). 

TPM can be said to be the Japanese Total Quality approach applied to 

maintenance. It is very much a people-driven approach, in contrast to 

RCM which is hardware approached (26).  

The aims of TPM are (26,60,62–64):  

• Maximise equipment effectiveness 



43 

• Optimise the maintenance system to maximise equipment 

effectiveness 

• Make sure the entire company is involved 

• Make sure that all employees are involved, by developing 

autonomous small group activities.  

The pillars of TPM, as shown in Figure 2.7, are defined as (65):  

1. Increase equipment effectiveness by eliminating the major losses 

2. Train operators to do low-level maintenance (Kaizen principle) 

3. Planned maintenance must be in place 

4. A maintenance prevention plan must be in place 

5. There must be training of operators in plant fundamentals 

6. Office TPM must ensure productivity and efficiency levels are 

increased whilst also considering administrative functions while 

identifying losses 

7. Emphasis on creating a safe workplace that is not hindered by the 

procedures and practices. 

 

Figure 2.7: Pillars of TPM (60) 



44 

The final TPM metric is a measurement of the overall equipment 

effectiveness (OEE) which is determined as the multiple of the plant 

availability, rate of production and the quality of the works produced in 

relation to total discard works (26,62,64). The goals of TPM can be 

summarized and achieved by the four “zeroes” as described below.  

• Zero Breakdowns –achieved by cleaning of the plant, adherence to 

operating conditions, restoration of plant to original condition, 

correct design flaws, Increase operator and artisan skills and 

training (26,63). 

• Zero Adjustments - This step will only proceed once zero 

breakdowns phase has been achieved and encompasses the 

operations of the system, plant or equipment. (26) 

•  Zero Idling and Zero Defects - These steps aims to minimise idling 

conditions and reduce stoppages  by installing relevant alarms, 

ensuring operator vigilance, measurement of time lost due to idling 

and avoiding overproduction or quality defects (26,63). 

2.4.6 Maintenance Steering Group 3  

Maintenance Steering Group 3 (MSG 3), which adopts a similar approach 

to that of RCM, is a methodology that maps out the organisation structure 

and processes in order to determine scheduled maintenance actions. 

MSG 3 was developed and pioneered for use in the airline and power 

generation industries with a view to sustain a high level of safety and 

reliability (66). MSG-3 is a detailed methodology that’s core focus area is 

on maintaining and improving maintenance regimes in the aircraft industry 

(67). This strategy is similar to RCM except questions are focused around 

lubrication of components and equipment (26). The MSG method of 

determining initial maintenance strategy is as follows (67):  

• Determine the operationally important items.  

• Utilising OEM supplied data and information  

• Determine failure modes and effects. 



45 

• Determine suitable and operative maintenance tasks (Repair, 

replace, monitor);  

• Determine intervals for all tasks.  

2.4.7 Maintenance Strategy Selection 

Failure prevention is the key driver behind any maintenance regime or 

plan, which is particularly true for conveyor belt systems. Regular actions 

and tasks to maintain equipment will firstly ensure safety of the personnel 

and plant but will also prolong equipment life and improve profitability. 

Lack of proper maintenance may result in increased downtime, costs and 

labour with reduced revenue. These provide a great motivator to consider 

the use of an effective and suitable maintenance strategy or strategies on 

the equipment (68). 

Some of the challenges faced by maintenance teams are as follows (11): 

1. Selecting and applying the most suitable and effective strategy and 

techniques 

2. Identifying and conducting maintenance tasks to deal with each 

independent failure mode and type  

3. Conducting and implementing maintenance tasks with least 

financial impact  

4. Ensuring asset owners, staff and all relative stakeholders’ 

expectations are met  

A common thread in many previous studies indicate the importance of the 

alignment between business strategies and maintenance strategies 

(13,16,49,59,69). The first step in maintenance strategy selection as 

prescribed by similar studies (15,47,70–74) suggest a maintenance plan 

and objectives be retrieved from business goals and objectives. By 

considering maintenance objectives it becomes simpler to identify, prepare 

and develop maintenance plans and schedules for a particular 

maintenance strategy (13). These objectives aim to achieve increased 



46 

levels of performance through efficient maintenance planning and actions 

(75). The understanding of the operation and its link to the commercial 

market are critical in ensuring profitability of the business. This feeds into 

the concept of feeding maintenance objectives from the business vision 

and goals (13). 

The selected maintenance strategy is required to be supported by logical 

sequencing and plans that realistically can be implemented (8). 

Furthermore, it is important to ensure that the maintenance strategies 

undergo a periodic review process due to the changing environment and 

business requirements. The important items to consider in developing and 

selecting a maintenance strategy are as follows (8,13):  

• Maintenance strategy development begins with a philosophy or 

goal that bests describes the maintenance practices and the 

development of maintenance objectives.  

• The maintenance strategy selected must ensure that the 

maintenance goals and objectives are aligned and obtained from 

the business goals and vision  

• Assess and evaluate the maintenance actions, tasks and 

challenges as and when issues and maintenance failures are 

experienced. 

A theoretical framework in selecting a maintenance strategy for plants and 

processing plants presented by McAllister (75) describes that maintenance 

must integrated with business objectives and goals in order to ensure the 

overall goal of the organisation can be achieved with acceptable revenue. 

Therefore it is critical to ensure that any maintenance approach, plan or 

policy is directly derived and aligned with the business strategy (75).  

The maintenance strategy should act as a pathway for maintenance that 

allows for agile and flexible adaptation with clear direction to adjust to any 

environment and scenario. This pathway should be developed from 

historical data within the organisation and its own goals as well as 



47 

benchmarked against international standards (13). The implementation of 

maintenance strategies is a difficult task for maintenance management 

personnel in many industries and organisations. Every company or 

organisation has its own challenges and face different problems 

dependent on the objectives, that is business and maintenance objectives 

(13,47). 

 Previous studies 

In this section some of the previous studies that have been conducted to 

identify a method for maintenance strategy selection are reviewed and 

analysed in order to guide the steps forward for this research project.  

Based on previous studies by Bevilacqua, Fredriksson, Mungani, 

Rashidpour and Velmurugan (13,15,47,51,59), it has been noted that the 

maintenance strategy selection in any organisation, plant or system in 

varying fields are typically a Multiple Criteria Decision Making (MCDM) 

problem. To overcome this problem the authors used multi-criteria 

decision-making tools such as Analytic Hierarchy Process (AHP) and 

Multi-Criteria Analysis (MCA).  

Alsyouf (76) identified a MCDM methodology for selecting the most 

informative maintenance approach for a paper mill industrial firm (76). The 

study described the role of cost-effective maintenance in achieving 

competitive advantages and conducted a survey in its initial stages to 

determine the current maintenance practices used and how they were 

selected. The study further developed a model to select the most suitable 

maintenance policy in terms of cost to implement and actual maintenance 

costs, as well as improving the effectives of the decision making in 

maintenance tasks. The main results from this study showed the utilisation 

of the FMECA to categorise and prioritise areas of concern, together with 

the need to select a practical approach to maintenance tailored to the 

system or subsystem at hand. This in the view of the researcher points to 

an RCM approach (76).  



48 

Salonen (16) formulated a maintenance strategy procedure for a 

processing and manufacturing plant based on three important aspects; 

company mission and vision, company strategic goals, and the strategic 

goals of maintenance (16). This research considered the manufacturing 

industry in developing a cost effective and simple approach to develop, 

implement and assess maintenance strategies. The research developed a 

process to select maintenance strategies (16).  

Zaim (73) attempted to develop a method for maintenance strategy 

selection using AHP and ANP methods (73) for a local newspaper printing 

facility in Turkey. The purpose of this paper was to illustrate two methods 

utilised in general decision making to select the most suitable 

maintenance approach for companies or industries. The two methods, 

AHP and ANP, proved effective in selecting a suitable approach to 

maintenance for printing machines. The two methods resulted in very 

similar results. The research showed that these methods and techniques 

can be applied to varying industries and companies to select maintenance 

strategies (65).  

El-dogdog (77) describes RCM as the integrated approach that links the 

work of FMECA and Ishikawa Fishbone diagram in its process which was 

adopted in a Toshiba glass factory (77). It was found that the FMECA and 

Ishikawa Fishbone methods can assist maintenance personnel of any 

plant or industry by decreasing the risk of severe failures. This research 

identified failure modes, risk priority numbers (RPN’S) and the revised 

RPN’s when the remedial actions were applied (77). 

Deshpande (18) applied the concept of RCM to a medium scale steel 

industry through systematically applying RCM techniques by analysing 

failures, failure causes and effects on the system (18). The study 

acknowledged the need for different and varying maintenance approaches 

for the different pieces of equipment. The study found that RCM can be 

applied to the manufacturing industry to improve overall performance and 

reduce maintenance costs (18).  



49 

Vishnu (14) stated that RCM selects the most suitable maintenance 

strategy for equipment and components in the industry based on its 

criticality score and reliability parameters which was based on a case 

study conducted on a titanium oxide plant (14). The plant conveys titanium 

oxide through use of a feed screw conveyor. This paper proposes a broad 

approach to implement Reliability Centred Maintenance (RCM) in process 

plants. The study highlighted the importance of surveys and considering 

expert personnel opinions from the maintenance and production 

departments. The model developed in the study was validated against the 

maintenance historical data of the titanium oxide plant. The plant had 

shown signs of following a combination of planned and reactive 

maintenance strategies. The implementation of RCM was justified through 

simulation results which indicated poor availability and performance of 

equipment with the existing maintenance approach (14).  

Carretero (20) investigated scenarios in applying RCM to large scale 

railway infrastructure to achieve an effective and structured maintenance 

approach and found RCM to be promising technique due to its 

introspective approach with regards to technical areas, its multidisciplinary 

approach to conduct analyses and its requirement of detailed and 

structured documentation and reporting (20).  

Fore and Msipha (78) conducted a case study on a ferrochrome 

processing plant where preventive maintenance techniques were 

investigated through application of RCM (78). This research had 

determined the neglect of preventive maintenance measures which 

directly affects the operations of the plant. This formed the basis of the 

research paper’s RCM approach which was used to create a maintenance 

strategy to address the majorly failing equipment. The result was a 

maintenance initiative that focuses limited resources in areas of high risk 

and concern that would cause the most severe damage and consequential 

damage (78). 

 



50 

Gerike (28) conducted a study at a coal mine with a significant number of 

conveyors in operation. The study encompassed determining failure 

causes and failure rates through use of actual failure data and 

investigating predictive tools, vibration monitoring, to monitor equipment. 

The research concluded that the use of vibration monitoring equipment 

had reduced failures to the equipment by prompting maintenance activities 

(28).  

Yuan (30) conducted a case study to select a maintenance strategy for a 

blast furnace conveyor belt. This paper presents a reliability simulation to 

assess and link different maintenance strategies. The study had defined 

systems and sub-systems before evaluating and categorising failures, 

functions and failure modes. The study utilised a MCDM tool, namely 

pairwise MCA tool, to select an appropriate maintenance strategy. This 

study found that maintenance conducted on individual components based 

on its own characteristics improves reliability and performance, which 

points to a tailored approach to maintenance, i.e. RCM (30). 

Kumar (79) conducted a study to analyse the operating parameters, 

maintenance procedures and the plant availability for a critical conveyor 

system in a coal mine in India. The research utilised existing failure data to 

conduct analyses. The scope of this research had considered seven 

subsystems that make up the critical conveyor system. This research 

paper prioritises areas of concern through ranking of failures according to 

severity, similar to that of an FMECA. It further measures the criticality of 

each component based on the failure data which deduced the downtime, 

repair time and availability of that component and subsystem. The study 

had concluded that plant parameters such as the reliability and availability 

can be improved by introducing proper maintenance techniques and 

strategies but it did not allude to what strategy would be the most effective 

(79).   

Zimroz (80) developed a research paper which intended to provide the 

status quo on existing research practices focused on maintenance of belt 



51 

conveyors. The study concluded that simply applying predictive 

maintenance initiatives through fully automated methods poses many 

challenges and may not be the final solution with further research required 

ascertain the most suited maintenance strategy or combination of 

strategies. This leads the researcher to believe a tailored maintenance 

approach is required (80). 

Ojha (27) conducted a research study that focused on belt conveyors in a 

coal handling plant. The study utilised the Fishbone technique to briefly 

identify failure causes. It further prioritised failures in a process similar to 

the FMECA. It identified the importance of determining root causes prior to 

selecting a maintenance approach. The research concluded that there are 

early stage improvement in reducing costs and improving efficiency when 

following the approach of identify failure causes and scenarios prior to 

maintenance strategy selection (27).   

It can be noted that there have not been many studies that consider 

maintenance strategy selection for conveyor belt systems. However, it is 

noted from the previous studies that that the procedures encountered in 

maintenance strategy selection can be applied to other industries, i.e. 

conveyor belt systems.  

 Research Method Types 

The purpose of any research or study is to investigate and identify 

patterns, sequences, trends or possible responses to a predetermined set 

of questions. The key aim when conducting any research is to uncover 

layers of data to reveal the answer to the objectives (81). 

The research process generally follows the below steps (81):  

1. Formulating the research problem;  

2. Detailed literature survey and developing the hypothesis or CRQ;  

3. Preparing the research design and methods;  

4. Collecting, collating and analysis of data;  



52 

5. Results interpretation and presentation, and  

6. Formal conclusions and recommendations. 

The objective of research is to arrive at an answer for a defined problem or 

set of questions, with the use of available data in order to provide possible 

solutions and recommendations. With this in mind, research methods can 

be put into the following three groups (81,82): 

• Data collection methods. These methods will be utilised in 

scenarios where the actual data available is insufficient to arrive at 

a solution  

• Analytical methods. That is the statistical techniques which are 

used for establishing relationships between the data and the 

unknowns; 

• Results Comparison. These approaches are utilised to are used to 

gauge the accuracy of the results obtained. 

The latter two methods above are considered as the analytical tools of 

research. Research can be conducted using various methods with the 

most common being qualitative and quantitative research methods. 

Qualitative studies do not enable the researcher to deduce cause–and–

effect relationships (83). Quantitative research can be defined as a 

process using statistical procedures to analyse data in order to examine 

the cause-and-effect relationship (84).  

Qualitative research methods are commonly linked to the study and 

investigation of social and cultural aspects. Qualitative methods generally 

provide results that can be termed as open-ended, based on ideas and 

concepts that have been utilised in the research. Qualitative methods are 

able to deduce relationships and conclusions based on the feelings and 

thoughts of personnel, which allows flexibility in the structure of the report 

(84,85). The qualitative method allows for fluidity in the research 

development. This approach is suited to investigating and exploring the 

nature of problems without quantification. The foremost objective in 



53 

qualitative studies are to define the changes between any phenomena or 

scenario. Qualitative research methods were established in the social 

aspects of research to study and examine socio-cultural occurrences (82). 

Quantitative research is a method that measures objective hypotheses 

drawn on the relationships and link between quantifiable information and 

data. The data can be measured and analysed utilising statistical 

techniques or tools. This provides the final report to have a more rigid 

structure than that of the qualitative process in that the structure would 

generally consist of chapters such as introduction, literature, research 

approach and methods, results and discussion, and conclusion and 

recommendations (86). Quantitative methods are most suited to 

understand the extent of problems and challenges by identifying and 

grasping relationships and changes between them (82). The techniques 

used in quantitative research include random selection of respondents, 

questionnaires and surveys, as well as statistical analytic tools to test and 

identify relationships of the outputs. The researcher in quantitative 

methods is external to the actual research and the results (86). 

Mixed methods research is a research approach that involves the use of 

both quantitative and qualitative information and data, which are integrated 

to draw conclusions and recommendations in the social and theoretical 

frameworks. The main assumption in this mixed methods approach is that 

the integrated use of qualitative and quantitative data and analysis tools 

provide a complete view and understanding of the research problem and 

objectives (84,85,87,88). 

Table 2.1 shows the comparisons between qualitative and quantitative 

research. 

 



54 

Table 2.1: Comparison of Qualitative and Quantitative Research 
Methods (87) 

Qualitative Quantitative 

Induction 

Purposes  

• Develops notion based on studies. 
• Focused on finding or unearthing principles.  

Procedures  

• Developing design. 
• Combines and collates information for 

analysis.	 

Deduction 

Purposes  

• Proves data and theory through 
investigations.  

• Focus on determining measured results  

Procedures  

• Fixed scope and area of works. 
• Distinguishes between information 

collected and analysis methods and 
results  

Subjectivity 

Purposes  

• Highlights the descriptions, behaviours and 
understandings  

• Attempts to comprehend views and 
standpoints 

Procedures  

• Researcher closely associated with 
information collected.  

• Researcher acts as the “research 
instrument.”  

Objectivity 

Purposes  

• Highlights items which are measurable 
or can be calculated  

• Outcomes are independent of opinions 
or views  

Procedures  

• The academic is divorced from the 
information collected  

• Reliance on measures, procedures and 
standards to deduce results  

Context 

Purposes  

• Focuses on precise detail  
• Evaluates complete structures.  

Procedures  

• Considers life-like methods and tactics  
• Dependent on low volume of data  

Generality 

Purposes  

• Focuses on simplified approach and 
repetitive patterns 

• Considers numerous settings 
(Environment, people, etc.).  

Procedures  

• Utilises statistical and measured 
methods  

• Focuses on a higher volume of 
information and data.  

 



55 

The author decides on the type of study that is to be undertaken when 

considering and selecting the research methods approach, be it a 

qualitative, quantitative, or mixed methods study (84). Research studies 

and designs are types of analyses and investigations within these 

research methods procedures that give the researcher guidance in terms 

of the direction the research design or study will take (84). 

2.6.1 Data collection 

The undertaking of data collection starts at the definition or understanding 

of a research problem. The type of data forms an integral part in setting 

and planning out the research. There are generally two types of data that 

can be collected, that is primary and secondary data. The primary data 

consists of information that are new and have not been seen or published 

before, appearing as original data. The secondary data consists of 

information that has already been published in previous studies or journals 

and has been put through a series of statistical and analytical processes. 

Data collection for primary and secondary differ in that primary data is 

original and must be collected for the first time whilst secondary data can 

be considered a compilation of works that have already been conducted 

(81). 

Primary Data 

Primary data can be collected in the course of experiments during 

experimental research and can also be obtained through direct or indirect 

communication with research participants. It is represented as the actual 

data received. This research makes use of the actual failure data and 

maintenance logs from the port (81). 

Secondary Data 

Secondary data refers to information and data that are available through 

previous research and studies. With the use of secondary data, it is 

important to investigate the multiple sources to corroborate the 



56 

information. Secondary data may take the form of either circulated and 

published data or uncirculated and unpublished data (81,84). 

Surveys and Questionnaires 

Surveys are a widespread technique used to collect and analyse data from 

primary sources using various collection methods that involve a series of 

questions tailored to obtain relevant and pertinent information from 

respondents. Surveys provide flexibility when requesting information and 

dependent on the structure and types of questions posed, can result in 

both qualitative and quantitative information (81,85). Surveys are flexible 

and can easily be combined with other methods to give detailed insight 

into the data (89). Survey design involves determining the sample 

population and determining the method/s of approach, i.e. interviews, 

questionnaires, online platforms etc. It also entails identification of an 

accepted response rate and level of accuracy which is highly depended on 

the subject of the survey (90).  

When conducting a survey, it is important to understand what format of 

survey is required. There are two survey formats (85): 

• Cross-sectional surveys are surveys that obtain relevant 

information a group at a particular point in time and attempts to 

investigate and determine correlations between two distinct factors   

• Longitudinal surveys are surveys that obtain information over a 

specified duration. This method will allow analysis of changes within 

the actual group of respondents and attempt to draw relationships 

and conclusions from that. A longitudinal survey also attempts to 

determine correlations between distinct factors but this is done 

considering the change in factors over the specified duration as 

opposed to the distinct difference between them, e.g. relationship 

between the wellbeing of an employee and the employment period 

of that employee.   



57 

2.6.2 Research Validity and Reliability 

Some method that are utilised to ensure validity and reliability of the 

research are as follows (81,84): 

• Triangulate various sources of data and information by scrutinising 

the data, comparing relevant studies and data to each other and 

utilising it to develop a logical process flow for achieving research 

objectives  

• Utilise peer reviews to verify and confirm accuracy levels when 

conducting qualitative research by giving research participants the 

opportunity to review the final report findings.  

• Use a rich, thick description to convey the findings. This approach 

will elevate the peers to provide a detailed perspective of the 

research process and its findings.  

• Identify and discuss any subjectivity that may arise or exist from the 

researcher. This presents a transparent view to the reader  

• Expend sufficient time on site in the surroundings relevant to the 

research. This provides the researcher with detailed first-hand 

experience in understanding site conditions, problems and possible 

remedies. This also improves level of accuracy in that the 

researcher is able to identify and communicate directly with the 

relevant personnel. 

 Analysis tools 

A variety and assortment of statistical procedures and tools can be utilised 

to analyse research data and information. These statistical methods or 

tools may be split into descriptive or inferential statistics. Descriptive 

statistics refers to those that are used to illustrate and describe the 

information whilst inferential statistics are those that are utilised to conduct 

the actual analysis of the data to draw relationships. There are various 

ways that data can be analysed but ultimately that is based on the study 

objectives and the data available (91). 



58 

2.7.1 Pareto Principle 

The Pareto principle is a statistical tool that enables its user to identify and 

select a specific item or number of items that result in the most significant 

effect. It utilises the principle of determining the top 20% of causes that 

result in 80% of failures or issues. The numbers do not have to be 20% 

and 80% exactly, but must show a distinct view between the causes in 

order to identify the causes with the greatest impact. The purpose is to 

ascertain the items accounting for the majority of the results, then 

introduce tools such as the FMECA, Ishikawa diagram or Five Whys to 

identify the root causes of the problems (92). Generally, in maintenance 

practice the Pareto analysis is used to prioritise maintenance activities. A 

Pareto histogram is a graphical representation of the results from a Pareto 

analysis and can be used for successful identification and ranking of 

failure events contributing to downtime (93). 

2.7.2 Failure Modes, Effects and Criticality Analysis   

A failure modes, effects and criticality analysis (FMECA) is a reliability 

assurance technique with first official use recorded from the late 1940’s 

(26). The FMECA is used to categorise and evaluate any probable failure 

modes of critical components of a system, the consequences or effects 

these failures may have on the system and how to circumvent the failures, 

and/or alleviate the failure consequences or effects (56). The FMECA is 

an adaptation and progression from the originally developed FMEA 

(Failure modes and effects analysis) with the addition of the C for the 

criticality (or severity) of the various failure effects which are now factored 

into the analysis (56). The objective of FMECA is to determine possible 

remedial actions that need to be implemented in order to reduce failure 

effects and consequences. The fundamental intention is to induce actions 

that will reduce the likelihood of failures. The severity, probability of 

occurrence and detection probability are scored and ranked to determine a 

risk priority number or rating (RPN). 



59 

The basic questions asked in an FMECA are the following (26,56):  

• How will each component or item possibly fail?  

• What causes or events lead to these failure modes? 
 

• What are the consequences or effects of the failures? 

• How can the failures be detected?  

• What existing measures or provisions are made to prevent failure? 

The failure modes, consequences and effects for critical components are 

typically detailed on schedules. The documentation involves the following 

(7,26):  

1. Description of the different components and their intended functions 

that ensure operability of the equipment or plant.  

2. Description of the failures which involves highlighting the various 

modes of failure, causes and events that give rise to these failure 

modes, and the numerous methods and probability of detection for 

the failure modes  

3. Detailing the failure effects on the system and possible 

consequential effects the failure could have on the system and 

other components  

4. The severity, probability of occurrence and detection probability of 

the failures are detailed and scored in line with a weighted scoring 

criterion to determine a ranking referred to as a Risk Priority 

Number (RPN). The RPN ranks the failure modes in the order of 

which failure will require action first. The higher the RPN the more 

serious the failure.  

2.7.3 Weibull Analysis 

Failure can be defined as the inability of a component or system to 

continue to function, rendering it unable to perform to its specified 

performance requirements (56). They can be divided into two main types; 

catastrophic failures which occur suddenly and completely, and 



60 

degradation failures in which the system or component gradually loses 

ability to function (94). 

The Weibull analysis is a model commonly used in statistics to detail the 

failure distribution and operating life of equipment and components in a 

variety of industries such as aircraft and aerospace, automotive 

manufacturing and assembly, materials handling, process industries, 

electronics, etc. (95). The use of Weibull analysis technique allows the 

researcher to determine the failure distribution pattern from which reliability 

conclusions can be presumed, such as the failure pattern and types (26).  

There are three common failure patterns i.e. infant mortality, random and 

wear-out failure. Infant mortality are failures that occur prematurely and 

are generally a sign of a quality issue within the system (26). Random 

failure, also referred to as constant failure rate, occurs in a pattern within a 

specific period (94). A very different type of failure is wear-out failure, 

which occurs toward end of life of a component after providing its useful 

life or design life with appropriate maintenance actions (26).  

2.7.4 The Five Whys 

The Five Whys technique is an ingenuous problem-solving methodology 

used to unravel any difficulty or issues by repeatedly asking the question 

“Why”, to unpack the various layers of signs that can lead to the root 

cause of a problem. The Five Whys adopts similar principles to that of 

systematic problem solving (96). The Five Whys methodology was 

pioneered within the automobile industry, specifically at Toyota by Sakichi 

Toyoda (26). This approach is commonly used to identify underlying 

problems and root causes in equipment failures and safety related 

incidents (97). The intended use of this technique is to, on the surface, 

briefly identify the root cause of the failures (96). This method of root 

cause may appear simple and often gets used incorrectly. Caution must 

be given when conducting a Five Whys to ensure that when asking 

questions, the real root cause is identified. The five in the “Five” Whys 



61 

analysis is a rule of thumb and more or less Whys can be asked before 

finding the root of a problem (97).  

2.7.5 Ishikawa Diagram 

Ishikawa diagrams, also referred to as Fishbone diagrams, are diagrams 

that depict the possible causes of a specific event. The process first starts 

with the failure event or problem that has occurred within the equipment or 

component which forms the main bone of the fishbone diagram (98). 

Distinct categories related to the component or equipment branch off 

forming further bones and depict the primary causes to the failure event 

with further secondary causes identified within each distinct category (98). 

Typical categories of the diagram include (26): 

• People: Staff involved in the maintenance of the conveyor belts 

• Methods: Maintenance procedures, plans and requirements  

• Machines: Any equipment, computers, tools required to complete 

the works successfully  

• Materials: Raw materials, splices, steel, idler brackets, etc. required 

to maintain operation 

• Measurements: Data generated from the conveying that are used to 

evaluate its throughput and uptime, (no condition monitoring in 

PORB) 

• Environment: The conditions within the PORB; location, 

temperature, etc. 

The components of a conveyor system, environment of operation, 

maintenance procedures and operational staff generally form part of the 

primary cause with external influence such as the commodity changeovers 

forming part of the secondary causes (27).  

 



62 

2.7.6 Multi Criteria Analysis (MCA) 

A Multi Criteria Analysis is a logical process to determine a “most 

favourable” option across multiple criteria. When considering how “good” 

any solution or option is, many factors or criteria need to be considered. 

The MCA aims to score the options independently against a set of criteria 

to deduce the single best go forward option or combination of options to 

meet project requirements (99,100). The general process followed during 

an MCA is shown in Figure 2.8. 

 

Figure 2.8: Flow diagram of MCA process (99) 

 

MCA Scoring Methodology 

Each option is given a score between 1 and 10 where a 1 is a flawed but 

possible solution, and a 10 is ideal. The scores are related to the approach 

particular to that specific criterion (99).  

 

 

Define & Confirm 
Evaluation 

Criteria 

•Factors that influence a maintenance 
strategy selection (Cost, Safety, 
Schedule, Value added)

Define & Confirm 
Criteria 

Weighting 

•Different criteria will carry 
different weightings as not all 
criteria are equally important. 

Score each 
maintenance 

strategy against 
the criteria 

•Scoring based on 
survey questionnaire 

Select most 
suited 

maintenance 
strategiy/strateg

ies



63 

The 1-10 scale is described as follows:  

• 9-10 –Ideal  

• 6-8 – Acceptable  

• 4-5 – Can be improved  

• 1-3 – Possible but has many challenges  

The scores received are then weighted and tallied to provide a 

percentage. The percentage is then compared to the other options and 

ranked accordingly to determine and select the most suited option across 

all the criteria (99) 

 Literature Review Summary 

This literature review aims to capture the essence of the analysis methods 

to be