Preface

Power plants are the backbone of industrial development for most countries and their failures impact economic growth. When failures or forced shutdowns in power plants occur, they are often due to boiler failure, and particularly failure of boiler tubes. The many causes of boiler tube failures include overheating, creep, erosion, corrosion, fatigue, manufacturing and material defects, and operational issues. Boiler tube failures lead to unscheduled shutdowns, increased maintenance and repair costs, reduced plant load factors, and loss of available power. To prevent interruptions in the supply of power, it is critical to investigate the root cause of boiler tube failures and the resultant forced outages and to develop remedial measures for preventing the recurrence of similar failures in the future. Such investigations are also aimed at assessing the remaining life of the boiler tubes.

We have long-standing experience in the field of metallurgy and materials technology, failure investigations, remaining life assessment, and reviewing fitness for service of industrial plants and equipment, including power plants. We have performed a large number of failure investigations of boiler tubes and have made effective recommendations of remedial measures in problem solving for power and utility boilers. An attempt has been made in this book to share our knowledge and expertise in failure investigation of boiler tubes, for the benefit of user industries.

For non-metallurgists, a chapter has been devoted to basics of material science, metallurgy of steels, heat treatment, and structure-property correlation. Without adequate knowledge of physical metallurgy fundamentals of steels and related materials, understanding the mechanisms of boiler tube failure is almost impossible. A chapter on materials for the manufacture of boiler tubes deals with composition and application of different grades of steels and high-temperature alloys currently in use as well as future materials to be used in supercritical, ultra-supercritical, and advanced ultra-supercritical thermal power plants. A comprehensive discussion on different mechanisms of boiler tube failure is the heart of the book. A large number of case studies based on actual failures from the field have been cited along with photographs and microstructures in order to facilitate the discussion of the underlying theory behind the respective failure mechanisms. Chapters dealing with the role of advanced material characterization techniques in failure investigation and the role of water chemistry in tube failures are key contributions to the book.

This book will help not only the novice but also practicing engineers in the operation and maintenance departments of power plants, boiler tube manufacturers, research and development personnel concerned with power plants, academicians, and students. This book will not make plant personnel experts in analysis of boiler tube failures; however, it will certainly increase their awareness, and help them effectively communicate with specialists and experts from failure investigation agencies as well as with their own management. For academicians and research and development personnel, it will act as a valuable ready reference.

Finally, we have great pleasure in acknowledging the support and encouragement received from the Indian power industry, users of industrial boilers, and allied organizations. Our special thanks to the management of the power plants for whom we have performed failure investigations, for permitting us to use the data, especially in writing the case studies.

We would like to thank the editorial and production staff at ASM International, especially Karen Marken, senior managing editor, for her guidance and valuable contribution at various stages of manuscript preparation.

We are grateful to the late V.K. Bafna, founder of the TCR Group of companies, for his vision and relentless efforts in building a world-class investigation center. We would also like to thank our colleagues at TCR Advanced Engineering, Vadodara, India, for their support in preparation of the manuscript for this book.