Erosion-Corrosion Characterisation for Pipeline Materials Using Combined Acoustic Emission and ...

322 Pages·2014·6.96 MB·English

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Erosion-Corrosion Characterisation for Pipeline Materials Using
Combined Acoustic Emission and Electrochemical Monitoring

by
Jonathan Item Ukpai

Submitted in accordance with the requirements for the degree of
Doctor of Philosophy

The University of Leeds
School of Mechanical Engineering

July 2014

The candidate confirms that the work submitted is his own, except where work which
has formed part of jointly authored publications has been included. The contribution of
the candidate and the other authors to this work has been explicitly indicated below.
The candidate confirms that appropriate credit has been given within the thesis where
reference has been made to the work of others.
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The publications related to this work are as follows:
1. Ukpai J.I.; Barker R.; Hu X.; Neville A.; Exploring the erosive wear of X65 carbon
steel by acoustic emission method. Wear, Volume 301, Issues 1-2, pp. 370-382, 2013.
2. Ukpai J.I.; Barker R.; Hu X.; Neville A.; Determination of particle impacts and impact
energy in the erosion of X65 carbon steel using acoustic emission technique. Tribology
International Journal, Volume 65, pp. 161-170, 2013.
3. Ukpai J.I.; Barker R.; Hu X.; Neville A.; An in-situ investigation of flow-induced
corrosion and erosion-corrosion degradation of X65 pipeline materials using combined
acoustic emission and electrochemical techniques. CORROSION/2013 paper no.
2305, NACE International Conference, Orlando, FL 2013.
4. Ukpai J.I.; Barker R.; Neville A., A combined electrochemical and acoustic emission
technique for mechanistic and quantitative evaluation of erosion-corrosion and its
components. CORROSION/2014 paper no. 4180, NACE International Conference, San
Antonio, TX, 2014.
All the work in the papers mentioned above is a contribution of the candidate, under
the supervision of the co-authors.
This copy has been supplied on the understanding that it is copyright material and that
no quotation from the thesis may be published without proper acknowledgement.

The right of Jonathan I. Ukpai to be identified as Author of this work has been asserted
by him in accordance with the Copyright, Designs and Patents Act 1988.

© 2013 The University of Leeds and Jonathan I. Ukpai
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Acknowledgements
I want to thank my supervisors, Professor Anne Neville and Dr. Simon Hu for their kind
words of advice, encouragement, guidance, exposure and for taking me round the
world during conferences and symposia. I also thank my colleagues, Richard Barker
and Michael Bryant for answering all my numerous questions. My gratitude goes to our
lab technicians Ron Cellier, Graham Jakeman (of blessed memory) and Brian Leach
for their assistance in the production of component parts of my research facilities and
fixtures, and for constantly replenishing the laboratory consumables, and to Jacqueline
Kidd and Fiona Slade for their sincere and warm administrative support.
I am very grateful to all the people who made enormous sacrifices of their time, energy,
and resources to make this project possible. I will not be able to name them one by one
because of space. Specifically, I thank my wife (Alice) and my kids (David, Jonathan
and Michelle) for their love, patience and understanding throughout the period of the
PhD study. I promise to compensate you all for the fatherly love and care I denied you
during my late night research activities. I also thank my late father, Omezue (Chief)
Ukpai Item (who did not live to see the end of this project) and Mother, Mrs. Ugo Ukpai
for their prayers and parental support.
The staff and management of Petroleum Technology Development Fund (PTDF),
Abuja, Nigeria, I cannot thank you enough for paying my tuition fees and maintenance
allowance for three years in United Kingdom. All I have to say to you is, please do not
relent in your good work, always keep the flag flying. My gratitude also goes to the staff
and management of National Board for Technical Education (NBTE), Kaduna, Nigeria
for all their support.
Above all, I say a big thank you to God almighty, for His grace, provisions, protection,
good health and mercies throughout the period of this research. To Him alone I give all
the glory.
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Abstract
The prediction and monitoring of erosion and erosion-corrosion attack on oil and gas
pipeline materials in service is useful for facilities design, material selection and
maintenance planning so as to predict material performance accurately, operate safely,
and prevent unplanned production outages. Conventional methods such as failure
records, visual inspection, weight-loss coupon analysis, can be time-consuming and
can only determine erosion or erosion-corrosion rates when the damage has already
occurred.
To improve on this, the acoustic emission (AE) technique combined with
electrochemical monitoring was chosen and implemented in this study to investigate
and characterize erosion and erosion-corrosion degradation rates of oil and gas
pipeline materials (X65) under Submerged Impinging Jet (SIJ) systems in a saturated
CO environment. Measured acoustic emission energy was correlated with the mass
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loss from gravimetric measurement for different flow velocities and sand loadings.
Sand particle impacts were quantified and compared with theoretical predictions, and
the associated impact energies predicted from Computational Fluid Dynamics (CFD)
were correlated with measured acoustic emission energy and mass loss.
The combined acoustic emission and electrochemical monitoring (involving Linear
Polarisation Resistance (LPR) and Electrochemical Impedance spectroscopy (EIS))
helped to simultaneously investigate the surface reactivity of the corroding materials as
well as capture the sand impacts contribution during the erosion-corrosion degradation
processes. Results reveal that the effect of the mechanical damage which is not
sensed by in-situ electrochemical measurement is adequately captured by the AE
method, thus making the combined technique a novel approach for in-situ monitoring of
both the electrochemical and mechanical damage contributions of erosion-corrosion
degradation processes.
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Contents
Acknowledgements ................................................................................................i
Abstract ..................................................................................................................ii
Contents ................................................................................................................ iii
List of Figures ....................................................................................................... ix
List of Tables ...................................................................................................... xix
Nomenclature ....................................................................................................... xx
Abbreviations .................................................................................................... xxiii
Chapter 1 Introduction ..........................................................................................1
1.1 Motivation ...............................................................................................1
1.2 Aim and Objectives of Study ...................................................................5
1.3 Statement of Novelty and Scientific Contribution ....................................6
1.4 Thesis Outline ........................................................................................7
Chapter 2 Background Theory ..............................................................................9
2.1 Corrosion ................................................................................................9
2.2 Governing Mechanisms of Aqueous Corrosion ..................................... 10
2.3 Corrosion Thermodynamics .................................................................. 12
2.4 Corrosion Kinetics ................................................................................ 14
2.4.1 Mass Transport (Diffusion Controlled Mechanism) ....................... 15
2.4.2 Electrical Double Layer (EDL) ...................................................... 16
2.4.3 Charge Transfer (Activation Controlled Mechanism) .................... 18
2.5 Electrochemical Techniques for Corrosion Measurement ..................... 21
2.5.1 Principles of Three-Electrode Cell ................................................ 23
2.5.2 Uncertainties in Corrosion Measurement ..................................... 25
2.6 Alternating Current (AC) Corrosion Measurement ................................ 25
2.7 Forms of Aqueous Corrosion Attack ..................................................... 30
2.7.1 Uniform Corrosion ........................................................................ 30
2.7.2 Pitting Corrosion .......................................................................... 31
2.7.3 Galvanic Corrosion ...................................................................... 32
2.7.4 Flow-Induced Corrosion and Erosion-Corrosion .......................... 35
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2.8 Summary .............................................................................................. 35
Chapter 3 Literature Review I .............................................................................. 36
3.1 CO Corrosion ...................................................................................... 36
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3.1.1 Mechanisms ................................................................................ 36
3.1.2 Controlling Factors ....................................................................... 39
3.1.3 Mitigation ..................................................................................... 40
3.1.4 Models ......................................................................................... 40
3.1.5 Empirical Models ......................................................................... 41
3.2 Erosion ................................................................................................. 55
3.2.1 Mechanism .................................................................................. 55
3.2.2 Prediction .................................................................................... 57
3.2.3 Erosion Models ............................................................................ 57
3.2.4 Computational Techniques in Erosion Rate Prediction ................ 64
3.3 CO Erosion-Corrosion ......................................................................... 66
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3.3.1 Meaning ....................................................................................... 66
3.3.2 Factors Affecting Erosion-Corrosion ............................................ 67
3.3.3 Mechanisms of Erosion-Corrosion ............................................... 74
3.3.4 Prediction of Erosion-Corrosion ................................................... 76
3.3.5 Mitigation of Erosion-Corrosion .................................................... 82
3.4 Summary .............................................................................................. 85
Chapter 4 Literature Review II: Acoustic Emission (AE) ................................... 86
4.1 Introduction .......................................................................................... 86
4.2 Historical Background ........................................................................... 87
4.3 Meaning of Acoustic Emission .............................................................. 89
4.4 Signal Processing and Analysis Techniques ........................................ 92
4.4.1 Time–Domain Analysis ................................................................ 92
4.4.2 Frequency-Domain Analysis ........................................................ 93
4.4.3 Root Mean Square (RMS) ........................................................... 94
4.5 AE in Corrosion Prediction and Monitoring ........................................... 94
4.6 AE in Erosion Prediction and Monitoring ............................................... 99
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4.7 Mechanism of Energy Transfer ........................................................... 100
4.8 AE in Erosion-Corrosion Prediction and Monitoring ............................ 107
4.9 Summary ............................................................................................ 110
Chapter 5 Experimental Design, Materials and Procedures ........................... 111
5.1 Experimental Design .......................................................................... 111
5.1.1 Centrifugal Pump ....................................................................... 111
5.1.2 Dual Nozzle System .................................................................. 111
5.1.3 Two Sample Holders ................................................................. 111
5.1.4 Reservoir/Mixing Tank ............................................................... 112
5.1.5 Heating Device/Thermocouple ................................................... 112
5.1.6 CO Tube ................................................................................... 112
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5.1.7 Acoustic Emission (AE) Hardware ............................................. 113
5.1.8 Electrochemical Instruments ...................................................... 113
5.2 Materials ............................................................................................. 114
5.2.1 Specimen Material ..................................................................... 114
5.2.2 Specimen Geometry and Dimensions ........................................ 114
5.2.3 AE Test Cell/Specimen Holder ................................................... 115
5.2.4 Sand Particle Size and Shape ................................................... 116
5.3 Calibration .......................................................................................... 117
5.3.1 Flow Velocity and Sand Loading Calibration .............................. 117
5.3.2 Acoustic Emission (AE) Sensor Calibration ................................ 122
5.4 Experimental Procedures ................................................................... 126
5.5 AE Detection Gain Optimisation ......................................................... 129
Chapter 6 Results and Discussion: Erosive Wear Investigation .................... 135
6.1 Introduction ........................................................................................ 135
6.2 Results ............................................................................................... 135
6.2.1 Single Impingement Tests ......................................................... 136
6.2.2 Multiple Impingement Tests ....................................................... 138
6.2.3 Surface Analysis ........................................................................ 147
6.3 Discussion .......................................................................................... 151
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6.3.1 Single Impingement Test ........................................................... 151
6.3.2 Multiple Impingement Tests ....................................................... 153
6.3.3 Surface Analysis ........................................................................ 155
6.3.4 Mass Loss and AE Energy ......................................................... 157
6.3.5 Frequency Spectrum Analysis ................................................... 160
6.4 Summary ............................................................................................ 166
Chapter 7 Results and Discussion: Particle Impact and Impact Energy
Quantification ............................................................................................ 167
7.1 Introduction ........................................................................................ 167
7.2 Understanding Particle Impact Detection and Interpretation ............... 167
7.3 Results for Particle Impact .................................................................. 172
7.3.1 AE Event Count Rate ................................................................. 172
7.3.2 Particle Impacts Determination .................................................. 175
7.3.3 Particle Impacts Comparison with Theoretical Prediction ........... 177
7.4 Discussion for Particle Impact ............................................................ 180
7.4.1 AE Event Count Rate ................................................................. 180
7.4.2 Particle Impact Determination .................................................... 181
7.4.3 Measured Particle Impact Comparison with Theoretical
Prediction .................................................................................. 183
7.5 Impact Energy Investigation ............................................................... 183
7.5.1 Submerged Impinging Jet (SIJ) Model ....................................... 184
7.5.2 Prediction of Particle Motion and Impact Condition .................... 187
7.5.3 Results for Impact Energy Investigation ..................................... 195
7.5.4 Discussion for Impact Energy Investigation................................ 198
7.6 Erosion Rate Estimation ..................................................................... 199
7.7 Summary ............................................................................................ 201
Chapter 8 Results and Discussion: Combined In-Situ AE and LPR
Investigation of CO Flow-Induced Corrosion and Erosion-Corrosion . 202
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8.1 Introduction ........................................................................................ 202
8.2 Results and Discussion ...................................................................... 202
8.2.1 Flow-Induced Corrosion ............................................................. 202
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8.2.2 Erosion-Corrosion ...................................................................... 207
8.2.3 Weight Loss and AE Energy ...................................................... 213
8.2.4 Main Findings ............................................................................ 216
8.3 Summary ............................................................................................ 217
Chapter 9 Results and Discussion: Mechanistic and Quantitative Evaluation
of Erosion-Corrosion and Its Components with Combined EIS and AE218
9.1 Introduction ........................................................................................ 218
9.2 Results ............................................................................................... 219
9.2.1 Tests without Sand .................................................................... 219
9.2.2 Test with Sand ........................................................................... 222
9.3 Equivalent Circuit Modelling of EIS Plots ............................................ 226
9.4 Discussion .......................................................................................... 230
9.4.1 7 m/s Flow Velocity .................................................................... 230
9.4.2 Investigation of the Inductive Loop in the 7 m/s EIS Plots .......... 234
9.4.3 10 and 15 m/s Flow Velocities ................................................... 236
9.4.4 Determination of Corrosion Rate ................................................ 239
9.5 Evaluation of Erosion-Corrosion Degradation and Its Components .... 242
9.6 Summary ............................................................................................ 247
Chapter 10 Overview and General Discussion ................................................ 248
10.1 Introduction ........................................................................................ 248
10.2 Erosion ............................................................................................... 248
10.2.1 Erosive Wear .................................................................... 249
10.2.2 Particle Impact Determination ........................................... 253
10.2.3 Impact Energy Quantification ............................................ 253
10.3 Corrosion ............................................................................................ 254
10.3.1 Flow-Induced Corrosion .................................................... 255
10.3.2 Erosion-Corrosion ............................................................. 256
10.3.3 Mechanistic and Quantitative Evaluation of Erosion-
Corrosion ................................................................................... 257
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Chapter 11 Conclusions and Recommended Future Work ............................. 262
11.1 Conclusions ........................................................................................ 262
11.1.1 Chapter 6 Findings ............................................................ 262
11.1.2 Chapter 7 Findings ............................................................ 264
11.1.3 Chapter 8 Findings ............................................................ 265
11.1.4 Chapter 9 Findings ............................................................ 266
11.2 Recommended Future Work ............................................................... 267
References ......................................................................................................... 269
Appendices ........................................................................................................ 292