Page 17 - Corrosion Engineering Principles and Practice

CHAPTER 1

The Study of

Corrosion

1.1 Why Study Corrosion?
Most people are familiar with corrosion in some form or another,
particularly the rusting of an iron fence and the degradation of steel
pilings or boats and boat fixtures. Piping is another major type of
equipment subject to corrosion. This includes water pipes in the
home, where corrosion attacks mostly from the inside, as well as the
underground water, gas, and oil pipelines that crisscross our land.
Thus, it would appear safe to say that almost everyone is at least
somewhat familiar with corrosion, which is defined in general terms
as the degradation of a material, usually a metal, or its properties
because of a reaction with its environment.
This definition indicates that properties, as well as the materials
themselves, may and do deteriorate. In some forms of corrosion, there
is almost no visible weight change or degradation, yet properties
change and the material may fail unexpectedly because of certain
changes within the material. Such changes may defy ordinary visual
examination or weight change determinations.
In a modern business environment, successful enterprises cannot
tolerate major corrosion failures, especially those involving personal
injuries, fatalities, unscheduled shutdowns, and environmental
contamination. For this reason considerable efforts are generally
expended in corrosion control at the design stage and in the
operational phase. This is particularly true for industries where harsh
chemicals are handled routinely.
Corrosion can lead to failures in plant infrastructure and machines
which are usually costly to repair, costly in terms of lost or contaminated
product, in terms of environmental damage, and possibly costly in
terms of human safety. Decisions regarding the future integrity of
a structure or its components depend upon an accurate assessment
of the conditions affecting its corrosion and rate of deterioration.

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