Author: Masanobu Matsumura

Erosion-Corrosion: An Introduction to Flow Induced Macro-Cell Corrosion

Personal Book: US $55 Special Offer (PDF + Printed Copy): US $135
Printed Copy: US $108
Library Book: US $220
ISBN: 978-1-60805-497-8
eISBN: 978-1-60805-351-3 (Online)
Year of Publication: 2012
DOI: 10.2174/97816080535131120101

Introduction

Erosion-corrosion is a generic name of degradation phenomena which occur on the chemical plant composing metallic materials under the conditions of various flowing liquids. For example, it occurs on heat transfer pipes of seawater heat exchangers (made of copper base alloys), casings of seawater pumps (made of gray cast iron) and carbon steel pipes which transport pure water of high temperature and pressure. Pipes made of carbon steel have sufficient strength and are simple and inexpensive to process. These are commonly used to transfer de-ionized water. Sudden and fatal explosion accidents have occurred in succession due to carbon steel pipes involved in high-temperature de-ionized water transport in thermal and nuclear power plants. The phenomenon was named FAC (flow accelerated corrosion) without the exact cause being clarified. It is a strongly suspected cause of the serious accident in 1986 with four victims which arose in the Surry nuclear power plant in Virginia, U.S.A.

Erosion-Corrosion is a compilation of nearly five decades of research on this theme throughout and demonstrates one true colour of this phenomenon; erosion-corrosions are not the product of the cooperation of erosion and corrosion, in which they may be generally believed, but are pure electrochemical corrosions in nature and usually occur in copper based alloys.

This e-book contains descriptions on erosion-corrosion testing methods and case studies carried out on the accidents which have occurred in the real chemical plants. Testing equipment helps us to estimate the erosion-corrosion damage in the laboratory and data of successive accidents in the field allows us to study the mechanisms behind it.

The mechanisms brought to light in this e-book are useful for predicting the site of incidence in chemical plants and the degree of the damage. In consequence, it is a useful tool for designing, material selection and maintenance of safer hydraulic machines and chemical plants, seawater pumps and piping in nuclear power plants.

Preface

Erosion-corrosion is a generic name for the degradation phenomenon that occurs in chemical plants, in which metallic materials are exposed to various flowing liquids. For example, erosion-corrosion occurs within heat-transfer pipes made of copper-based alloys that are used in seawater heat exchangers. Moreover, it also takes place within both casings of seawater pumps made of gray cast iron and carbon steel pipes that transport pure water at high temperature and pressure, etc. Erosion-corrosion was the likely cause of a serious accident in the United States in 1986 that killed four workers at Surry nuclear power plant located in the state of Virginia.

A half century ago, in 1962, the author was a freshman of the master course of Tokyo Institute of Technology. His supervisor was Professor Yoshitada Suezawa who belonged to the department of chemical engineering. He instructed the students that the mechanical engineers in the field might be disposed to classify the erosion-corrosion in corrosion, but the chemical engineers classify it into erosion, so the boundary region of erosion and corrosion must be the underdevelopment region to be elucidated. He also recommended the student to boldly begin with the opposite side of the region, that is, the cavitation erosion.

For nearly five decades, the author has expanded his research field from cavitation erosion to the whole area in the boundary region of erosion and corrosion, and made a recent notable discovery regarding the nature of erosion-corrosion. Contrary to the popular belief, erosion-corrosion in nature does not result from cooperation between erosion and corrosion; instead, it manifests from pure electrochemical corrosion, which should be classified as localized corrosion or macro-cell corrosion. This fact was proven by the author using both experimental and theoretical evidence. Experimental data showed no cooperation product between erosion and corrosion even when pure erosion and pure corrosion overlapped. Thus, it was concluded that erosion-corrosion is a pure corrosion process, rather than a cooperative process. A theoretical analysis using an Evans diagram indicated that erosion-corrosion is macro-cell corrosion that results from at least two different anodic polarization behaviors of the metal which are originated from differences in the flow conditions.

This book is sparing much space on erosion-corrosion testing methods and presents case studies conducted on accidents that have occurred at actual chemical plants. These topics were the focus of the research and, simultaneously, the means for reaching the conclusions: erosion-corrosion damage can only be studied in the laboratory with the appropriate testing equipment; and, erosion-corrosion data from accidents in the field are still needed to study the mechanisms responsible for erosion-corrosion. Testing methods cannot be developed without complete clarification of the mechanisms responsible for erosion-corrosion damage.

For many years, the author belonged to the chemical engineering department of Hiroshima University. One of the purposes of the chemical engineering is to support the chemical industries in the field. Therefore, the end-result of this research will not be the elucidation of the mechanism by which erosion-corrosion degrades structural materials in a chemical facility. Rather, identification of the mechanisms of erosion-corrosion will enhance the ability to predict both the locations of accidents in chemical plants and the degree of damage that might result. In addition, identification of the erosion-corrosion mechanisms will be useful for both the design and material selection of hydraulic machines and chemical plants, such as for seawater pumps and piping in nuclear power plants, and for maintenance and safety management.

Masanobu Matsumura
Higashi-Hiroshima, Hiroshima
mmatsu@rapid.ocn.ne.jp

RELATED BOOKS

.Fundamentals and Prospects of Catalysis.
.Single and Two-Phase Flows on Chemical and Biomedical Engineering.
.Catalytic Materials for Hydrogen Production and Electro-oxidation Reactions.