Failure Analysis and Modification Analysis for the Seal Face
in
Mechanical Sealby
Muhammad Izwan bin Mohammad Safaruddin
Dissertation Report submitted in partial fulfillment of the requirements for the
Bachelor of Engineering (Hons) (Mechanical Engineering)
Universiti Teknologi PETRONAS Bandar Seri Iskandar
31750Tronoh Perak Darul Ridzuan
MAY2011
Table of Contents
CERTIFICATION ... v
ABSTRACT ... . vii
ACKNOWLEDGEMENT ... ... viii
CHAPTER I: INTRODUCTION I. BACKGROUND STUDY ... 1
2. PROBLEM STATEMENT ... 2
3. OBJECTIVES ... 3
4. SCOPE OF STUDY ... 3
CHAPTER 2: LITERATURE REVIEW AND THEORY I. MECHANICAL SEAL CONCEPT ... 4
2. SEAL FACE DESIGN ... 5
3. GENERAL THEORIES ON THERMAL CONDITION ... 7
3.1Thermal Expansion on Ring Shaped Materials ... 7
3.2Heat Generated Due to Viscous Drag ... 8
3.3Thermal Deflections ... 10
3.4Thermal Conduction (Heat Transfer) ... I 0 4. Failure of Mechanical Seal ... 12
4.1 Seal Life ... 12
4.2Type of Failures ... 12
4.2.1 Leaking ... 13
4.2.2 Contamination ... 15
4.2.3 Appearance Change ... 16
CHAPTER 3: METHODOLOGY/PROJECT WORK 1. PROJECT WORKFLOW ...•... 17
2. RESEARCH METHODOLOGY ... 18
CHAPTER 4: RESULTS AND DISCUSSION 1. DESIGN OF BASIC MECHANICAL SEAL ... 19
2. SETTINGS FOR THE ANALYSIS OF THE SEAL FACES ... 21 Page
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i2.1 Material Properties ... 21
2.2Structural Stress Analysis ... 22
2.2.1 General Settings ... 22
2.2.2 Connections ... 22
2.2.3 Mesh ... 24
2.2.4 Fixities ... 25
2.2.5 Applied Load ... 26
2.3Thermal Analysis ... 26
2.3.1 General Settings ... 26
2.3.2 Connections ... 27
2.3.3 Mesh ... 27
2.3.4 Applied Load ... 28
2.4Fluid Flow Analysis ... 28
2.4.1 General Settings ... 28
2.4.2 Fluid Flow Model ... 29
2.4.3 Mesh ... 29
2.4.4 Boundary Conditions ... 30
3. RESULTS OF THE ANALYSIS OF THE CURRENT SEAL FACE ... 31
3.1Structural Stress Analysis ... 31
3.1.1 Maximum Principle Stress Analysis ... 32
3.1.2 Maximum Shear Stress Analysis ... 33
3.2Deformation Analysis ...•... 34
3.3Safety Factor Analysis ... 35
3.4Thermal Analysis ... 36
3.5Fiushing Fluid Flow Analysis ... 37
4. MODIFICATIONS OF THE SEAL FACE DESIGN ... 38
5. RESULTS OF THE ANALYSIS OF THE MODIFIED SEAL FACE ...••....•.•.•.•.•...••....•..•...•....•. 41
5.1Structural Stress Analysis ... 41
5.1.1 Maximum Principle Stress Analysis ... 42
5.1.2 Maximum Shear Stress Analysis ... 43
5.2Deformation Analysis ... 43
5.3Safety Factor Analysis ...•... 44
5.4Inner Seal Face Thermal Analysis ... 45
5.5Fiushing Fluid's Flow Analysis ... 46
6. CALCULATION ... 47 Page Iii
6.1Balance Ratio Calculation ... 4 7
6.2Thermal Expansion Calculation ... 47
6.3Heat Generated Calculation ... 48
6.4Prandt'l Number Calculation ... 49
6.5Heat Convection Coefficient Calculation ... 50
6.6Calculation for Heat Generation Due to Viscous Drag ... 51
7. ANALYSIS SUMMARY ... 52
CHAPTER 5: CONCLUSION ... ... 55
CHAPTER 6. APPENDICES APPENDIX 6.1 :_APPENDIX A - SAMPLE OF DRAWING MANUAL_(ST A TIONARY SEAL FACE) ... 57
APPENDIX 6.2:_APPENDIX B- SAMPLE OF SIMULATION MANUAL_(ROTATING SEAL FACE) ... 66
REFERENCE. ... . 71
LIST OF FIGURES Figure I: Basic Mechanical Seal.. ... .4
Figure 2: Stationary and Rotary Parts ofMechanical Seal ... 5
Figure 3: Sample Mechanical Seal System ... 6
Figure 4: Thermal Expansion Diagram ... 7
Figure 5: Heat Dissipation on Seal Face Diagram ... II Figure 6: Possible Seal Leakage Points ... l3 Figure 7: Fishbone Diagram on Failure Causes of Mechanical Seal (Leaking) ... l4 Figure 8: Fishbone Diagram on Failure Causes of Mechanical Seal (Contamination) ... 15
Figure 9: Fishbone Diagram on Failure Causes of Mechanical Seal (Appearance Change) ... l6 Figure 10: Project Workt1ow ... l7 Figure II: Disassembling Parts of Single Seal.. ... .20
Figure 12: Location of Rotating Seal Face ... 20
Figure 13: Location of Stationary Seal Face ... 21
Figure 14: Fluid Flow Cavity Model. ... 29
Figure 15: Mesh on the Cavity Model.. ... 30
Figure 16: Maximum Principal Stress of Current Model.. ... 32
Figure 17: Maximum Shear Stress of Current Model. ... .33
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iiiFigure 18: Total Deformation of Current Model. ... 34
Figure 19: Mohr Coulomb Safety Factor of Current Model.. ... .35
Figure 20: Mesh on the Cavity Model.. ... 36
Figure 21: Flushing Fluid Flow for Current Mode1.. ...•... 37
Figure 22: First Modification on the Seal Face ... 38
Figure 23: Current Seal Face Model with Slot Design ... 39
Figure 24: Assembly ofNew Shrink-Fitted Seal Face ... .39
Figure 25: Graph of Seal Face Metal Body Deformation versus Temperature ... .40
Figure 26: Graph of Seal Face Metal Body Deformation versus Applied Pressure ... .40
Figure 27: Maximum Principle Stress of Modified Model.. ... .42
Figure 28: Maximum Shear Stress of Modified Model.. ... .43
Figure 29: Total Deformation of Modified Model. ... .44
Figure 30: Mohr Coulomb Safety Factor for Modified Model ... .44
Figure 31: Thermal Analysis for Modified Design ... 45
Figure 32: Flushing Fluid Flow Pattern for Modified Design ... .46
LIST OF TABLES
Table I: Part List of Single Balanced Seal ... 19Table2: Properties of Stainless Steel ... 21
Table 3: Properties of Silicon Carbide ... 22
Table 4: Structural Stress Analysis General Settings ... 22
Table 5: Connections for Current Model Stress Analysis ... 23
Table 6: Current Model Meshing Element ... 25
Table 7: Type of Fixities Used in FEA Analysis ... 25
Table 8: Applied Load on Current Model Structural Stress Analysis ... 26
Table 9: Thermal Analysis General Settings ... 26
Table l 0: Connections for Current Model Thermal Analysis ...•... 27
Table II: Applied Load on Current Model Thermal Analysis ... 28
Table 12: Fluid Flow Analysis General Settings ... 29
Table 13: Boundary Conditions for Current Model Fluid Flow Analysis ... 30
Table 14: Type on Analysis Done on the Current Model.. ... .31
Table 15: Type of Analysis Done on the Modified Model... ... 41
Table 16: Comparison of Analysis between Current Seal Face and Modified Design ... 52
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ivCERTIFICATION OF APPROVAL
Failure Analysis and Modification Analysis for the Seal Face
Approved by,
in Mechanical Seal
by
Muhammad Izwan bin Mohammad Safuruddin
A project dissertation submitted to the Mechanical Engineering Programme
Universiti Teknologi PETRONAS in partial fulfilment of the requirement for the
BACHELOR OF ENGINEERING (Hons) (MECHANICAL ENGINEERING)
(Mohd Faizairi bin Mohd Nor)
Molul Falzairi Mobd Nor
"-""'
- l!uiiaeaina Proaronuoc
Ulllwrsld To:knolotli PETRONAS )'1750 Tronoh
Petak Darul Ridzuan, M.U.,.Siia
UNIVERSITI TEKNOLOGI PETRONAS TRONOH, PERAK
August 2011
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vCERTIFICATION OF ORIGINALITY
This is to certifY that I am responsible for the work submitted in this project, that the original work is my own except as specified in the references and acknowledgements, and that the original work contained herein have not been undertaken or done by unspecified sources or persons.
MUHD £ MOHD SAFARUDDIN
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