Control of Pipeline Corrosion
Filed under: CIVIL and ARCHITECTURE, MAINTENANCE, MECHANICAL, PETROLEUM,OIL and NATURAL GAS, REFRIGERATION and HVAC ENGINEERING
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WHAT IS CORROSION?
One general definition of corrosion is the degradation of a material through environmental interaction. This definition encompasses all materials, both naturally occurring and man-made and includes plastics, ceramics, and metals. This book focuses on the corrosion of metals, with emphasis on corrosion of carbon and low-alloy steels used in underground pipelines. This definition of corrosion begs the question; why do metals corrode? The answer lies in the field of thermodynamics, which tells whether a process such as corrosion will occur. A second logical question is what is the rate of corrosion or how long will a pipeline last? Corrosion kinetics can help provide an answer to this question. Both topics are discussed in greater detail in Chapter 16. Chapter 1 contains an introduction to the subject of underground corrosion. A glossary of terms is included in Appendix A of this book to help with the sometimes confusing terminology.
A significant amount of energy is put into a metal when it is extracted from its ores, placing it in a high-energy state. These ores are typically oxides of the metal such as hematite (Fe2O3) for steel or bauxite (Al2O3.H2O) for aluminum. One principle of thermodynamics is that a material always seeks the lowest energy state. In other words, most metals are thermodynamically unstable and will tend to seek a lower energy state, which is an oxide or some other compound. The process by which metals convert to the lower-energy oxides is called corrosion.
Tags: Control of Pipeline Corrosion, Corrosion, pipe, Pipe Corrosion, piping