Handbook of Corrosion Engineering Pierre R. Roberge McGraw-Hill New York San Francisco Washington, D.C. Auckland Bogotá Caracas Lisbon London Madrid Mexico City Milan Montreal New Delhi San Juan Singapore Sydney Tokyo Toronto 0765162_FM_Roberge 9/1/99 2:36 Page iii Library of Congress Cataloging-in-Publication Data Roberge, Pierre R. Handbook of Corrosion Engineering / Pierre R. Roberge. p. cm. Includes bibliographical references. ISBN 0-07-076516-2 (alk. paper) 1. Corrosion and anti-corrosives. I. Title. TA418.74.R63 1999 620.1'1223—dc21 99-35898 CIP Copyright © 2000 by The McGraw-Hill Companies, Inc. All rights reserved. Printed in the United States of America. 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If such services are required, the assistance of an appropriate professional should be sought. 0765162_FM_Roberge 9/1/99 2:36 Page iv Contents Preface ix Acknowledgments xi Introduction 1 1.1 The Cost of Corrosion 1 1.2 Examples of Catastrophic Corrosion Damage 3 1.3 The Influence of People 5 References 12 Chapter 1. Aqueous Corrosion 13 1.1 Introduction 13 1.2 Applications of Potential-pH Diagrams 16 1.3 Kinetic Principles 32 References 54 Chapter 2. Environments 55 2.1 Atmospheric Corrosion 58 2.2 Natural Waters 85 2.3 Seawater 129 2.4 Corrosion in Soils 142 2.5 Reinforced Concrete 154 2.6 Microbes and Biofouling 187 References 216 Chapter 3. High-Temperature Corrosion 221 3.1 Thermodynamic Principles 222 3.2 Kinetic Principles 229 3.3 Practical High-Temperature Corrosion Problems 237 References 265 0765162_FM_Roberge 9/1/99 2:36 Page v Chapter 4. Modeling, Life Prediction and Computer Applications 267 4.1 Introduction 267 4.2 Modeling and Life Prediction 268 4.3 Applications of Artificial Intelligence 303 4.4 Computer-Based Training or Learning 322 4.5 Internet and the Web 324 References Chapter 5. Corrosion Failures 331 5.1 Introduction 332 5.2 Mechanisms, Forms, and Modes of Corrosion Failures 332 5.3 Guidelines for Investigating Corrosion Failures 359 5.4 Prevention of Corrosion Damage 360 5.5 Case Histories in Corrosion Failure Analysis 368 References 369 Chapter 6. Corrosion Maintenance Through Inspection And Monitoring 371 6.1 Introduction 372 6.2 Inspection 374 6.3 The Maintenance Revolution 6.4 Monitoring and Managing Corrosion Damage 406 6.5 Smart Sensing of Corrosion with Fiber Optics 448 6.6 Non-destructive Evaluation (NDE) 461 References 481 Chapter 7. Acceleration and Amplification of Corrosion Damage 485 7.1 Introduction 486 7.2 Corrosion Testing 488 7.3 Surface Characterization 562 References 574 Chapter 8. Materials Selection 577 8.1 Introduction 578 8.2 Aluminum Alloys 584 8.3 Cast Irons 612 8.4 Copper Alloys 622 8.5 High-Performance Alloys 664 8.6 Refractory Metals 692 8.7 Stainless Steels 710 8.8 Steels 736 8.9 Titanium 748 8.10 Zirconium 769 References 777 Chapter 9. Protective Coatings 781 9.1 Introduction 781 9.2 Coatings and Coating Processes 782 Contents 0765162_FM_Roberge 9/1/99 2:36 Page vi 326 383 9.3 Supplementary Protection Systems 829 9.4 Surface Preparation 831 References 831 Chapter 10. Corrosion Inhibitors 833 10.1 Introduction 833 10.2 Classification of Inhibitors 834 10.3 Corrosion Inhibition Mechanism 838 10.4 Selection of an Inhibitor System 860 References 861 Chapter 11. Cathodic Protection 863 11.1 Introduction 863 11.2 Sacrificial Anode CP Systems 871 11.3 Impressed Current Systems 878 11.4 Current Distribution and Interference Issues 886 11.5 Monitoring the Performance of CP Systems for Buried Pipelines 904 References 919 Chapter 12. Anodic Protection 921 12.1 Introduction 921 12.2 Passivity of Metals 923 12.3 Equipment Required for Anodic Protection 927 12.4 Design Concerns 930 12.5 Applications 932 12.6 Practical Example: Anodic Protection in the Pulp and Paper Industry 933 References 938 Appendix A. SI Units 939 Appendix B. Glossary 947 Appendix C. Corrosion Economics 1001 C.1 Introduction 1001 C.2 Cash Flows and Capital Budgeting Techniques 1002 C.3 Generalized Equation for Straight Line Depreciation 1004 C.4 Examples 1006 C.5 Summary 1009 References 1009 Appendix D. Electrochemistry Basics 1011 D.1 Principles of Electrochemistry 1011 D.2 Chemical Thermodynamics 1029 D.3 Kinetic Principles 1047 0765162_FM_Roberge 9/1/99 2:36 Page vii Appendix E. Chemical Compositions of Engineering Alloys 1061 Appendix F. Thermodynamic Data and E-pH Diagrams 1101 Appendix G. Densities and Melting Points of Metals 1125 Index 1129 Contents 0765162_FM_Roberge 9/1/99 2:36 Page viii Chapters 1 to 3) contains fundamental principles governing aqueous corrosion and high-temperature corrosion and covers the main environ- ments causing corrosion such as atmospheric, natural waters, seawater, soils, concrete, as well as microbial and biofouling environments. The second section (Chapters 4 to 7) addresses techniques for the pre- diction and assessment of corrosion damage such as modeling, life pre- diction, computer applications, inspection and monitoring and testing through acceleration and amplification of corrosion damage. The second section also contains a detailed description of the various types of corro- sion failures with examples and ways to prevent them. The third section (Chapters 8 to 12) covers general considerations of corrosion prevention and control with a focus on materials selection. This chapter is particu- larly valuable for its detailed descriptions of the performance and main- tenance considerations for the main families of engineering alloys based on aluminum, copper, nickel, chrome, refractory metals, titanium and zirconium, as well as cast irons, stainless steels and other steels. This section also provides elements for understanding protective coatings, corrosion inhibitors, cathodic protection and anodic protection. The first appendix contains a table of appropriate SI units making references to most other types of units. This table will hopefully com- pensate for the systematic usage of SI units made in the book. Another appendix is an extensive glossary of terms often used in the context of corrosion engineering. A third appendix summarizes corrosion econom- ics with examples detailing calculations based on straight value depre- ciation. The fourth appendix provides a detailed introduction to basic electrochemical principles. Many examples of E-pH (Pourbaix) dia- grams are provided in a subsequent appendix. The designations and compositions of engineering alloys is the subject of a fifth appendix. Pierre R. Roberge Preface 0765162_FM_Roberge 9/1/99 2:36 Page x 1 I.1 The Cost of Corrosion 1 I.2 Examples of Catastrophic Corrosion Damage 3 I.2.1 Sewer explosion, Mexico 3 I.2.2 Loss of USAF F16 fighter aircraft 3 I.2.3 The Aloha aircraft incident 3 I.2.4 The MV KIRKI 4 I.2.5 Corrosion of the infrastructure 4 I.3 The Influence of People 5 Introduction Corrosion is the destructive attack of a material by reaction with its environment. The serious consequences of the corrosion process have become a problem of worldwide significance. In addition to our every- day encounters with this form of degradation, corrosion causes plant shutdowns, waste of valuable resources, loss or contamination of prod- uct, reduction in efficiency, costly maintenance, and expensive over- design; it also jeopardizes safety and inhibits technological progress. The multidisciplinary aspect of corrosion problems combined with the distributed responsibilities associated with such problems only increase the complexity of the subject. Corrosion control is achieved by recognizing and understanding corrosion mechanisms, by using corro- sion-resistant materials and designs, and by using protective systems, devices, and treatments. Major corporations, industries, and govern- ment agencies have established groups and committees to look after corrosion-related issues, but in many cases the responsibilities are spread between the manufacturers or producers of systems and their users. Such a situation can easily breed negligence and be quite cost- ly in terms of dollars and human lives. I.1 The Cost of Corrosion Although the costs attributed to corrosion damages of all kinds have been estimated to be of the order of 3 to 5 percent of industrialized countries’ gross national product (GNP), the responsibilities associat- ed with these problems are sometimes quite diffuse. Since the first sig- nificant report by Uhlig 1 in 1949 that the cost of corrosion to nations is indeed great, the conclusion of all subsequent studies has been that corrosion represents a constant charge to a nation’s GNP. 2 One conclu- sion of the 1971 UK government-sponsored report chaired by Hoar 3 was that a good fraction of corrosion failures were avoidable and that improved education was a good way of tackling corrosion avoidance. 0765162_Intro_Roberge 9/1/99 2:38 Page 1 Corrosion of metals cost the U.S. economy almost $300 billion per year at 1995 prices. 4 Broader application of corrosion-resistant mate- rials and the application of the best corrosion-related technical prac- tices could reduce approximately one-third of these costs. These estimates result from a recent update by Battelle scientists of an ear- lier study reported in 1978. 5 The initial work, based upon an elaborate model of more than 130 economic sectors, had revealed that metallic corrosion cost the United States $82 billion in 1975, or 4.9 percent of its GNP. It was also found that 60 percent of that cost was unavoid- able. The remaining $33 billion (40 percent) was said to be “avoidable” and incurred by failure to use the best practices then known. In the original Battelle study, almost 40 percent of 1975 metallic cor- rosion costs were attributed to the production, use, and maintenance of motor vehicles. No other sector accounted for as much as 4 percent of the total, and most sectors contributed less than 1 percent. The 1995 Battelle study indicated that the motor vehicles sector probably had made the greatest anticorrosion effort of any single industry. Advances have been made in the use of stainless steels, coated metals, and more protective finishes. Moreover, several substitutions of materials made primarily for reasons of weight reduction have also reduced corrosion. Also, the panel estimated that 15 percent of previously unavoidable corrosion costs can be reclassified as avoidable. The industry is esti- mated to have eliminated some 35 percent of its “avoidable” corrosion by its improved practices. Table I.1 summarizes the costs attributed to metallic corrosion in the United States in these two studies. 2 Introduction TABLE I.1 Costs Attributed to Metallic Corrosion in the United States 1975 1995 All industries Total (billions of 1995 dollars) $82.5 $296.0 Avoidable $33.0 $104.0 Avoidable 40% 35% Motor vehicles Total $31.4 $94.0 Avoidable $23.1 $65.0 Avoidable 73% 69% Aircraft Total $3.0 $13.0 Avoidable $0.6 $3.0 Avoidable 20% 23% Other industries Total $47.6 $189.0 Avoidable $9.3 $36.0 Avoidable 19% 19% 0765162_Intro_Roberge 9/1/99 2:38 Page 2 is a natural process that does not need human intervention to occur). What might be defined as purely mechanical failures occur when P m is high and P e is low. Most well-designed engineering systems in which P e is approximately 0 achieve good levels of reliability. The most successful systems are usually those in which the environmental influence is very small and continues to be so throughout the service lifetime. When P e becomes a significant influence on an increasing P sf , the incidence of cor- rosion failures normally also increases. Minimizing P sf only through design is difficult to achieve in practice because of the number of ways in which P m , P e , and Factor p can vary during the system lifetime. The types of people that can affect the life and performance of engineering systems have been regrouped in six categories (Table I.2). 13 Table I.2 also contains a brief description of the main contributions that each category of people can make to the suc- cess or premature failure of a system. Table I.3 gives an outline of methods of corrosion control 14 with an indication of the associated responsibility. However, the influence of people in a failure is extremely difficult to predict, being subject to the high variability level in human decision making. Most well-designed engineering systems perform according to specification, largely because the interactions of people with these sys- tems are tightly controlled and managed throughout the life of the sys- tems. Figure I.2 breaks down the causes responsible for failures 6 Introduction People (p) m Corrosion Failure Environmental Influence Materials in Service e Figure I.1 Basic fault tree of a corrosion failure. 0765162_Intro_Roberge 9/1/99 2:38 Page 6 [...]... diagrams Autocatalytic nature of pitting Tafel extrapolation for measurement of kinetic parameters Electrochemical noise signature of corrosion Study of corrosion processes with electrochemical impedance spectroscopy (EIS) 17 63 17 88 17 91 1 819 18 24 18 30 18 34 18 40 18 36 19 04 19 05 19 07 19 08 19 10 19 10 19 13 19 16 19 20 19 23 19 23 19 24 19 30 19 31 19 31 19 39 19 38 19 38 19 50 19 56 19 68 19 70 Source Boyle HMS Alarm report... Corrosion Cracking of Stainless Steels, in Shreir, L L., Jarman, R A., and Burstein, G T (eds), Corrosion Control Oxford, UK, Butterworths Heinemann, 19 94, pp 8:52–8:83 076 516 2_Ch 01_ Roberge 9 /1/ 99 2:46 Page 13 Chapter 1 Aqueous Corrosion 1. 1 Introduction 13 1. 2 Applications of Potential-pH Diagrams 16 1. 2 .1 Corrosion of steel in water at elevated temperatures 17 1. 2.2 Filiform corrosion 26 1. 2.3 Corrosion. .. ;;;;;; HFeO ;;;;;;;;;;;;;;; ;;;;;; ;;;;;; ;;;;;; 2 6 4 8 10 12 pH Potential (V vs SHE) 1. 6 0.8 Recommended pH operating range to minimize corrosion damage 3 0 2+ 2 2 -0.8 Fe -1. 6 0 2 4 6 8 10 12 14 pH Figure 1. 5 E-pH diagram of iron in water at 25°C and its observed corrosion behavior 076 516 2_Ch 01_ Roberge 9 /1/ 99 2:46 Page 21 Aqueous Corrosion 21 Potential (V vs SHE) example, no fewer than three engineers... Iverson Epelboin 076 516 2_Intro_Roberge 12 9 /1/ 99 2:38 Page 12 Introduction References 1 Uhlig, H H., The Cost of Corrosion in the United States, Chemical and Engineering News, 27:2764 (19 49) 2 Cabrillac, C., Leach, J S L., Marcus P., et al., The Cost of Corrosion in the EEC, Metals and Materials, 3:533–536 (19 87) 3 Hoar, T P., Report of the Committee on Corrosion and Protection 19 71 London, UK, Her Majesty’s... of Standards 6 Up Front, Materials Performance, 31: 3 (19 92) 7 Vasanth, K., Minutes of Group Committee T-9 - Military, Aerospace, and Electronics Equipment Corrosion Control, 3-30 -19 95 Houston, Tex., NACE International 8 Miller, D., Corrosion control on aging aircraft: What is being done? Materials Performance, 29 :10 11 (19 90) 9 Hamer, M., Clampdown on the Rust Buckets, New Scientist, 14 6:5 (19 91) 10 ... Broomfield, J P., Five Years Research on Corrosion of Steel in Concrete: A Summary of the Strategic Highway Research Program Structures Research, paper no 318 (Corrosion 93), 19 93 Houston, Tex., NACE International 11 Trethewey, K R., and Roberge, P R., Corrosion Management in the Twenty-First Century, British Corrosion Journal, 30 :19 2 19 7 (19 95) 12 Roberge, P R., Eliciting Corrosion Knowledge through the Fault-Tree... the range of 10 .5 to 11 at room temperature.5 This precaution takes the active corrosion field on the left-hand side of the E-pH diagrams out of play, as shown in the E-pH diagrams drawn for steel at two temperatures, 25°C (Fig 1. 5) and 210 °C (Fig 1. 6) At the recommended pH levels, around 11 , the E-pH diagram in Fig 1. 5 indicates the presence of thermodynamically stable oxides above the zone of immunity... - 2 Fe -1. 6 0 2 4 6 pH Figure 1. 6 E-pH diagram of iron in water at 210 °C 8 10 12 14 076 516 2_Ch 01_ Roberge 22 9 /1/ 99 2:46 Page 22 Chapter One Practical experience related to boiler corrosion kinetics at different feedwater pH levels is included in Fig 1. 5 The kinetic information in Fig 1. 5 indicates that high oxygen contents are generally undesirable It should also be noted from Figs 1. 5 and 1. 6 that... Stationary Office 4 Holbrook, D., Corrosion Annually Costs $300 Billion, According to Battelle Study, http://www.battelle.org/pr /12 corrode.html, 1- 1 -19 96, Battelle Memorial Institute 5 Bennett, L H., Kruger, J., Parker, R L., Passaglia, E., Reimann, C., Ruff, A W., and Yakowitz, H., Economic Effects of Metallic Corrosion in the United States: A Report to the Congress, NBS Special Pub 511 -1 1 -13 -19 78 Washington,... to the formation of an anodic metal dissolution site at the front of the head of the corrosion filament (Fig 1. 11) For iron, pH values at the front of the head of 1 to 4 and a potential of close to Ϫ0.44 V (SHE) have been reported In contrast, at the back of the head, where the cathodic reaction dominates, the prevailing pH is around 12 The conditions prevailing at the front and back of the head for . xi Introduction 1 1 .1 The Cost of Corrosion 1 1.2 Examples of Catastrophic Corrosion Damage 3 1. 3 The Influence of People 5 References 12 Chapter 1. Aqueous Corrosion 13 1. 1 Introduction 13 1. 2 Applications. Butterworths Heinemann, 19 94, pp. 8:52–8:83. 12 Introduction 076 516 2_Intro_Roberge 9 /1/ 99 2:38 Page 12 13 Aqueous Corrosion 1. 1 Introduction 13 1. 2 Applications of Potential-pH Diagrams 16 1. 2 .1 Corrosion of steel. Compositions of Engineering Alloys 10 61 Appendix F. Thermodynamic Data and E-pH Diagrams 11 01 Appendix G. Densities and Melting Points of Metals 11 25 Index 11 29 Contents 076 516 2_FM_Roberge 9 /1/ 99 2:36