SUPERVISOR DECLARATION “I hereby declare that I have read this thesis and in my opinion this thesis is sufficient in terms of scope and quality for the award of the degree of Bachelor of Mechanical Engineering (Plant and Maintenance) with honours” Signature : ................................... Supervisor : DR. MOHD YUSOFF BIN SULAIMAIN Date :
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SUPERVISOR DECLARATION
“I hereby declare that I have read this thesis and in my opinion this thesis is
sufficient in terms of scope and quality for the award of the degree of Bachelor of
Mechanical Engineering (Plant and Maintenance) with honours”
Signature : ...................................
Supervisor : DR. MOHD YUSOFF BIN SULAIMAIN
Date :
ii
DECLARATION
“I hereby declare that the work in this thesis is my own except for summaries and
quotations which have been duly acknowledged”
Signature : ...................................
Author : MOHAD KHALIL BIN MOHAD KHAZIN
Date :
iii
SPECIAL THANKS TO
MOTHER AND FATHER
FOR THE SUPPORTS AND ADVICES
iv
ACKNOWLEDGEMENT
First of all, I am grateful to ALLAH S.W.T. for establishing me to complete
this research and report.
I wish to express my sincere thanks to my family for their unceasing
encouragement and support in all aspect.
I place on record, my sincere gratitude to my supervisor, Dr Mohd Yusoff
Bin Sulaiman. I am extremely grateful and indebted to him for his expert, sincere and
valuable guidance and encouragement extended to me.
I take this opportunity to record my sincere thanks to all faculty members of
the Department of Plant and Maintenance, UTeM for their help and providing me
with all the necessary facilities.
I also place on record, my sense of gratitude to one and all who, directly or
indirectly, have lent their helping hand in this venture.
v
ABSTRACT
Failure analysis of structures has gained a considerable interest in many
engineering areas. The aim of this research is to determine the root cause of the
structural failures which can reduce the failure risks and prevent similar failures in
the future. This thesis presents experimental investigations for the failure of a super-
heater tube of a coal-fired power plant using several failure analysis procedures. The
failure analysis comprised of visual inspection, optical microscopic, ultrasonic
thickness measurement test and hardness test. A sample of a total-fractured super-
heater tube obtained from an industry was used in this investigation. Initial visual
investigations found that the super-heater tube had a longitudinal crack. This fracture
appearance is called fish mouth stress rupture. The ultrasonic thickness test is to
detect a significant oxide layer that occurs in the steam side surface. The optical
microscopy were used to identify intergranular cracks, voids, elongated grain and
deposit layers. The hardness test is to determine the resistance of material to
penetration after being heated. The results for the hardness test and ultra-thickness
test used to determine the rupture temperature and estimate the life period of the fail
tube using Larson Miller Parameter.
vi
ABSTRAK
Analisis kegagalan struktur telah menjadi satu keutamaan dalam bidang
kejuruteraan. Tujuan kajian ini adalah untuk menentukan punca kepada kegagalan
struktur yang boleh mengurangkan risiko kegagalan dan mengelakkan kegagalan
yang serupa pada masa hadapan. Tesis ini menceritakan tentang uji kaji terhadap
kegagalan tiub pemanas loji janakuasa arang batu menggunakan beberapa prosedur
analisis kegagalan. Analisis kegagalan terdiri daripada pemeriksaan visual,
mikroskopik optik, ujian ultrasonik pengukuran ketebalan dan ujian kekerasan. Satu
sampel tiub pemanas yang diperolehi daripada industri telah digunakan dalam
penyiasatan ini. Siasatan awal iaitu pemeriksaan visual mendapati tiub pemanas
mempunyai retak. Ini menunjukkan kegagalan yg telah berlaku pada tiub pemanas
dipanggil “fish mouth stress rupture”. Ujian ultrasonik pengukuran ketebalan adalah
untuk mengesan lapisan oksida yang berlaku di permukaan tiub di sebelah luaran.
The mikroskop optik telah digunakan untuk mengenal pasti kegagalan sejenis
“intergranular cracks”, “voids”, “elongated grain” dan “deposit layers”. Ujian
kekerasan adalah untuk menentukan ketahanan bahan untuk penembusan selepas
dipanaskan. Keputusan bagi ujian kekerasan dan ujian ultrasonic pengukuran
ketebalan telah digunakan untuk menentukan suhu pecah dan anggaran tempoh hayat
tiub gagal menggunakan “Larson Miller Parameter”.
vii
TABLE OF CONTENT
CHAPTER CONTENT PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENT vii
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF APPENDIX xii
CHAPTER I INTRODUCTION 1
1.1 BACKGROUND 1
1.2 PROBLEM STATEMENT 2
1.3 OBJECTIVE 3
CHAPTER II LITERATURE REVIEW 4
2.1 BOILER 5
2.1.1 Fire Tube Boiler 5
2.1.2 Water Tube Boiler 5
2.2 BOILER SUPERHEATER TUBE 7
2.2.1 Electric Resistance Weld Tube 8
viii
CHAPTER CONTENT PAGE
2.2.2 Seamless Tube 9
2.2.3 Alloys in Super-Heater Tube Material 10
2.3 DEFINITION OF FAILURE ANALYSIS 11
2.4 BOILER SUPERHEATER TUBE LEAK OR
FAILURE
13
2.4.1 Flue Gas Erosion (Outside Tube) 13
2.4.2 Pitting Corrosion or Oxygen
Corrosion (Inside Tube)
14
2.4.3 Thermal Fatigue 14
2.4.4 Short Term Overheating 15
2.4.5 Steam Cutting 16
2.4.6 Coal Ash Corrosion 17
2.4.7 Hydrogen Damage 18
2.5 LARSON MILLER PARAMETER 18
2.6 CREEP 19
CHAPTER III METHODOLOGY 20
3.1 INTRODUCTION 20
3.2 FLOWCHART OF THE RESEARCH 21
3.3 VISUAL INSPECTION 22
3.4 ULTRASONIC THICKNESS
MEASUREMENT
22
3.5 SAMPLE PREPARATIONS 23
3.5.1 Sectioning 23
3.5.2 Mounting 24
3.5.3 Grinding and Polishing Procedure 24
3.5.4 Etching 25
3.6 METALLOGRAPHIC EXAMINATION 25
3.7 HARDNESS TEST 25
3.7.1 Vickers Hardness Test 26
3.8 CREEP ANALYSIS 28
3.9 OXIDE SCALE THICKNESS 29
ix
CHAPTER CONTENT PAGE
CHAPTER IV RESULTS AND ANALYSIS 30
4.1 INTRODUCTION 30
4.2 VISUAL INSPECTION 30
4.3 ULTRASONIC THICKNESS
MEASUREMENT
31
4.4 HARDNESS TESTING RESULTS 32
4.5 LARSON-MILLER PARAMETER
ANALYSIS
34
4.5.1 Temperature Calculation Using Metal
Thickness
34
4.5.2 Temperature Calculation Using Oxide
Scale Thickness
35
4.5.3 Temperature Calculation Using Metal
Hardness
39
4.6 MICROSTRUCTURE EVALUATION 39
4.7 LIFE EXPECTANCY STUDY 43
4.8 RESULT ANALYSIS 45
CHAPTER V CONCLUSION AND RECOMMENDATION 46
5.1 CONCLUSION 46
5.2 RECOMMENDATION 47
BIBLIOGRAPHY 49
APPENDIX 52
APPENDIX A 53
APPENDIX B 54
APPENDIX C 55
APPENDIX D 56
APPENDIX E 57
x
LIST OF TABLES
TABLE TITLE PAGE
2.1 Water tube boiler versus fire tube boiler 7
2.2 Specification in general use for boiler tube (ASTM International, 2014) 9
2.3 Feritic alloys used in boiler tube (ASTM international, 2014) 10
2.4 Functions of alloying element (Chase Alloys Ltd, 2011) 11
4.1 Thickness measurement result 32
4.2 Vickers Hardness result from the tube sample 33