Explains why pipeline stress corrosion cracking happens and how it can be prevented
Pipelines sit at the heart of the global economy. When they are in good working order, they deliver fuel to meet the ever-growing demand for energy around the world. When they fail due to stress corrosion cracking, they can wreak environmental havoc.
This book skillfully explains the fundamental science and engineering of pipeline stress corrosion cracking based on the latest research findings and actual case histories. The author explains how and why pipelines fall prey to stress corrosion cracking and then offers tested and proven strategies for preventing, detecting, and monitoring it in order to prevent pipeline failure.
Stress Corrosion Cracking of Pipelines begins with a brief introduction and then explores general principals of stress corrosion cracking, including two detailed case studies of pipeline failure. Next, the author covers:
- Near-neutral pH stress corrosion cracking of pipelines
- High pH stress corrosion cracking of pipelines
- Stress corrosion cracking of pipelines in acidic soil environments
- Stress corrosion cracking at pipeline welds
- Stress corrosion cracking of high-strength pipeline steels
The final chapter is dedicated to effective management and mitigation of pipeline stress corrosion cracking. Throughout the book, the author develops a number of theoretical models and concepts based on advanced microscopic electrochemical measurements to help readers better understand the occurrence of stress corrosion cracking.
By examining all aspects of pipeline stress corrosion cracking - the causes, mechanisms, and management strategies - this book enables engineers to construct better pipelines and then maintain and monitor them to ensure safe, reliable energy supplies for the world.
Table of Contents
Foreword xiii
Preface xv
List of Abbreviations and Symbols xix
1 Introduction 1
1.1 Pipelines as “Energy Highways” 2
1.2 Pipeline Safety and Integrity Management 3
1.3 Pipeline Stress Corrosion Cracking 3
References 5
2 Fundamentals of Stress Corrosion Cracking 7
2.1 Definition of Stress Corrosion Cracking 7
2.2 Specific Metal–Environment Combinations 9
2.3 Metallurgical Aspects of SCC 11
2.3.1 Effect of Strength of Materials on SCC 11
2.3.2 Effect of Alloying Composition on SCC 11
2.3.3 Effect of Heat Treatment on SCC 11
2.3.4 Grain Boundary Precipitation 12
2.3.5 Grain Boundary Segregation 12
2.4 Electrochemistry of SCC 13
2.4.1 SCC Thermodynamics 13
2.4.2 SCC Kinetics 14
2.5 SCC Mechanisms 15
2.5.1 SCC Initiation Mechanisms 15
2.5.2 Dissolution-Based SCC Propagation 16
2.5.3 Mechanical Fracture–Based SCC Propagation 18
2.6 Effects of Hydrogen on SCC and Hydrogen Damage 20
2.6.1 Sources of Hydrogen 20
2.6.2 Characteristics of Hydrogen in Metals 21
2.6.3 The Hydrogen Effect 21
2.6.4 Mechanisms of Hydrogen Damage 25
2.7 Role of Microorganisms in SCC 27
2.7.1 Microbially Influenced Corrosion 27
2.7.2 Microorganisms Involved in MIC 29
2.7.3 Role of MIC in SCC Processes 31
2.8 Corrosion Fatigue 32
2.8.1 Features of Fatigue Failure 33
2.8.2 Features of Corrosion Fatigue 34
2.8.3 Factors Affecting CF and CF Management 35
2.9 Comparison of SCC, HIC, and CF 35
References 37
3 Understanding Pipeline Stress Corrosion Cracking 43
3.1 Introduction 43
3.2 Practical Case History of SCC in Pipelines 44
3.2.1 Case 1: SCC of Enbridge Glenavon Pipelines (SCC in an Oil Pipeline) 45
3.2.2 Case 2: SCC of Williams Lake Pipelines (SCC in a Gas Pipeline) 46
3.3 General Features of Pipeline SCC 46
3.3.1 High-pH SCC of Pipelines 47
3.3.2 Nearly Neutral–pH SCC of Pipelines 48
3.3.3 Cracking Characteristics 48
3.4 Conditions for Pipeline SCC 50
3.4.1 Corrosive Environments 50
3.4.2 Susceptible Line Pipe Steels 53
3.4.3 Stress 58
3.5 Role of Pressure Fluctuation in Pipelines: SCC or Corrosion Fatigue? 62
References 68
4 Nearly Neutral–pH Stress Corrosion Cracking of Pipelines 73
4.1 Introduction 73
4.2 Primary Characteristics 73
4.3 Contributing Factors 75
4.3.1 Coatings 75
4.3.2 Cathodic Protection 79
4.3.3 Soil Characteristics 81
4.3.4 Microorganisms 83
4.3.5 Temperature 85
4.3.6 Stress 85
4.3.7 Steel Metallurgy 88
4.4 Initiation of Stress Corrosion Cracks from Corrosion Pits 89
4.5 Stress Corrosion Crack Propagation Mechanism 96
4.5.1 Role of Hydrogen in Enhanced Corrosion of Steels 96
4.5.2 Potential-Dependent Nearly Neutral–pH SCC of Pipelines 99
4.5.3 Pipeline Steels in Nearly Neutral–pH Solutions: Always Active Dissolution? 101
4.6 Models for Prediction of Nearly Neutral–pH SCC Propagation 104
References 111
5 High-pH Stress Corrosion Cracking of Pipelines 117
5.1 Introduction 117
5.2 Primary Characteristics 117
5.3 Contributing Factors 118
5.3.1 Coatings 118
5.3.2 Cathodic Protection 119
5.3.3 Soil Characteristics 123
5.3.4 Microorganisms 125
5.3.5 Temperature 125
5.3.6 Stress 125
5.3.7 Metallurgies 128
5.4 Mechanisms for Stress Corrosion Crack Initiation 128
5.4.1 Electrochemical Corrosion Mechanism of Pipeline Steels in a Thin Layer of Carbonate–Bicarbonate
Electrolyte Trapped Under a Disbonded Coating 128
5.4.2 Conceptual Model for Initiation of Stress Corrosion Cracks in a High-pH Carbonate–Bicarbonate Electrolyte Under a Disbonded Coating 133
5.5 Mechanisms for Stress Corrosion Crack Propagation 137
5.5.1 Enhanced Anodic Dissolution at a Crack Tip 137
5.5.2 Enhanced Pitting Corrosion at a Crack Tip 143
5.5.3 Relevance to Grain Boundary Structure 144
5.6 Models for the Prediction of a High-pH Stress Corrosion Crack Growth Rate 144
References 145
6 Stress Corrosion Cracking of Pipelines in Acidic Soil Environments 149
6.1 Introduction 149
6.2 Primary Characteristics 150
6.3 Electrochemical Corrosion Mechanism of Pipeline Steels in Acidic Soil Solutions 151
6.4 Mechanisms for Initiation and Propagation of Stress Corrosion Cracks 151
6.5 Effect of Strain Rate on the SCC of Pipelines in Acidic Soils 154
References 157
7 Stress Corrosion Cracking at Pipeline Welds 159
7.1 Introduction 159
7.2 Fundamentals of Welding Metallurgy 160
7.2.1 Welding Processes 160
7.2.2 Welding Solidification and Microstructure 160
7.2.3 Parameters Affecting the Welding Process 162
7.2.4 Defects at the Weld 162
7.3 Pipeline Welding: Metallurgical Aspects 163
7.3.1 X70 Steel Weld 163
7.3.2 X80 Steel Weld 163
7.3.3 X100 Steel Weld 164
7.4 Pipeline Welding: Mechanical Aspects 164
7.4.1 Residual Stress 164
7.4.2 Hardness of the Weld 166
7.5 Pipeline Welding: Environmental Aspects 170
7.5.1 Introduction of Hydrogen into Welds 170
7.5.2 Corrosion at Welds 172
7.5.3 Electrochemistry of Localized Corrosion at Pipeline Welds 173
7.6 SCC at Pipeline Welds 178
7.6.1 Effects of Material Properties and Microstructure 178
7.6.2 Effects of the Welding Process 179
7.6.3 Hydrogen Sulfide SCC of Pipeline Welds 179
References 180
8 Stress Corrosion Cracking of High-Strength Pipeline Steels 185
8.1 Introduction 185
8.2 Development of High-Strength Steel Pipeline Technology 186
8.2.1 Evolution of Pipeline Steels 186
8.2.2 High-Strength Steels in a Global Pipeline Application 187
8.3 Metallurgy of High-Strength Pipeline Steels 189
8.3.1 Thermomechanical Controlled Processing 189
8.3.2 Alloying Treatment 189
8.3.3 Microstructure of High-Strength Steels 190
8.3.4 Metallurgical Defects 192
8.4 Susceptibility of High-Strength Steels to Hydrogen Damage 193
8.4.1 Hydrogen Blistering and HIC of High-Strength Pipeline Steels 193
8.4.2 Hydrogen Permeation Behavior of High-Strength Pipeline Steels 196
8.5 Metallurgical Microelectrochemistry of High-Strength Pipeline Steels 199
8.5.1 Microelectrochemical Activity at Metallurgical Defects 199
8.5.2 Preferential Dissolution and Pitting Corrosion Around Inclusions 203
8.6 Strain Aging of High-Strength Steels and Its Implication on Pipeline SCC 207
8.6.1 Basics of Strain Aging 208
8.6.2 Strain Aging of High-Strength Pipeline Steels 212
8.6.3 Effect of Strain Aging on SCC of High-Strength Pipeline Steels 214
8.7 Strain-Based Design of High-Strength Steel Pipelines 216
8.7.1 Strain Due to Pipe–Ground Movement 217
8.7.2 Parametric Effects on Cracking of Pipelines Under SBD 218
8.8 Mechanoelectrochemical Effect of Corrosion of Pipelines Under Strain 219
References 225
9 Management of Pipeline Stress Corrosion Cracking 231
9.1 SCC in Pipeline Integrity Management 231
9.1.1 Elements of Pipeline Integrity Management 231
9.1.2 Initial Assessment and Investigation of SCC Susceptibility 234
9.1.3 Classification of SCC Severity and Postassessment 235
9.1.4 SCC Site Selection 236
9.1.5 SCC Risk Assessment 238
9.2 Prevention of Pipeline SCC 240
9.2.1 Selection and Control of Materials 241
9.2.2 Control of Stress 242
9.2.3 Control of Environments 243
9.3 Monitoring and Detection of Pipeline SCC 244
9.3.1 In-Line Inspections 244
9.3.2 Intelligent Pigs 247
9.3.3 Hydrostatic Inspection 248
9.3.4 Pipeline Patrolling 249
9.4 Mitigation of Pipeline SCC 249
References 251
Index 255
