A large percentage of power, petroleum, and chemical plants the world over have been in operation for such long durations that the critical components in these plants have been used beyond the “design life” of 30 to 40 years. This percentage is likely to become even higher during the next decade. There are strong economic reasons and technical justifications for continued operation of these plants. In order to realize this in practice, however, techniques and methodologies are needed to assess the current condition of plant components and to project their remaining useful lives. This technology is also of value with respect to younger plants in the contexts of safety, availability, and reliability, and operation, maintenance, and inspection practices. There has been a flurry of research and development activities worldwide during the last few years relating to life-assessment technology for high-temperature components.
With respect to the theory of damage at high temperatures, many books and conference proceedings dealing with creep, fatigue, creep-fatigue, thermal fatigue, hot corrosion, and hydrogen attack have been published. These publications deal extensively with the mechanistic aspects of the various damage phenomena but fail to place them in the framework of an engineering approach. Furthermore, they address each damage phenomenon as a single issue, and fail to delineate the relationships between phenomena in the over-all context of component integrity. On the other hand, conference proceedings dealing with the engineering aspects of life assessment are component- specific and do not provide sufficient theory to enable a nonspecialist to fully comprehend the methodologies being discussed, A major objective of this book is to bring together in one place the theory and practice of damage assessment of high-temperature components. In accordance with this objective, the first four chapters lay the theoretical groundwork pertaining to damage phenomena, and are followed by illustrations of the practical application of the theory on a component-specific basis in the later chapters. Other objectives of this book are: (1) to provide a complete bibliography to methods, data, and case histories; (2) to provide relevant data with examples; (3) to provide empirical correlations and techniques that enable one to estimate those properties which are often difficult to determine, on the basis of others which are more readily obtained; and (4) to document recent advances in materials technology leading to increased reliability and longevity of components.
The published literature relating to the various damage phenomena described in this book is extensive and vast. It is impossible to provide “in depth” coverage of these phenomena in a single volume. Only a broad coverage of the various issues is therefore provided. Only those damage phenomena which result from high-temperature exposure are discussed. Most of the discussions center around low-alloy steels because these steels represent the largest tonnage of material used in plant construction.
Selection of the contents of this book has been based mainly on my close acquaintance with the concerns that preoccupy utility engineers. In particular, my interaction with the metallurgy and piping task force of the Edison Electric Institute was very useful in identifying the practical needs. It is hoped that this book will be useful to practicing metallurgists and mechanical engineers. In addition, it can also serve to expose college metallurgy students to the industrial aspects of the high-temperature- metallurgy curriculum. Because the features of many types of high-temperature failures are described, failure-analysis consultants may also find the book to be of some use.
This book was written during a sabbatical year that I spent as a visiting professor of metallurgy at the Indian Institute of Technology in Madras, India. I wish to thank Professor L.S. Srinath, the director of IIT Madras, and Professor V.M. Rad- hakrishnan, past chairman of the department of metallurgy, for allowing me this opportunity. I am also very grateful to the senior management at EPRI, particularly Dr. John Stringer, for granting me this sabbatical leave, for providing constant encouragement, and for allowing me the use of material from EPRI reports. Without the support of the Electric Power Research Institute and the extensive knowledge base developed through its research projects, this book would not have been possible. The various sections of the book were reviewed for technical accuracy by J.M. Allen, F. Ammirato, W.T. Bakker, E. Creamer, R.B. Dooley, F. Ellis, J. Foulds, G. Ibarra, R.I. Jaffee, C, Jaske, S.R. Paterson, M. Prager, A. Saxena, and V.P. Swaminathan. I am indebted to them for the many useful comments and suggestions for improvement that they provided. Several chapters were typed by Perky Perkins and were proofread by Mr. Nallathambi Kandaswamy. The thorough review of the manuscript by the copyeditor C.W. Kirkpatrick is greatly appreciated, I am also thankful to the publisher, ASM International. Timothy Gall of ASM was particularly helpful in streamlining the publication process. Last but not least, I wish to acknowledge the help of my wife Vatsala for her understanding and support in freeing me from many of the household chores during the writing of this book. This book is a humble dedication to Bhagawan Sri Ramana Maharshi.
Generation and Storage Division
Electric Power Research Institute
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