Page 416 - Corrosion Engineering Principles and Practice

CHAPTER 10

Corrosion in Soils

and Microbiologically

Influenced Corrosion

10.1 Introduction
Microbiologically influenced corrosion (MIC) is not restricted to soils
and as illustrated in Fig. 10.1 [1] may occur in most environments
where deposits can form. The muddy bottom of any relatively
stagnant body of water with a high biological oxygen demand often
supports massive growth of sulfate reducing bacteria (SRB), as may
waterlog soils. Any metallic installations buried or immersed in such
environments can be expected to suffer badly from microbiological
corrosion. The most serious economic problem is the corrosion of
pipelines, although sheet piles and piers are frequently attacked. In
some instances, cast iron pipes of 6.3 mm thickness have perforated
within the first year of operation under such conditions, while
perforation in three years is common. Even if MIC problems are not
restricted to soils, MIC is such an important factor in understanding
the corrosivity of most soils that it was decided to combine these two
topics in a single chapter.

10.2 Corrosion in Soils

It has long been observed that a piece of iron buried in a dry soil suffers
much less corrosion than when it is buried in a wet soil. However, soils
are commonly wet due to rain, natural springs, and rivers soils.
Corrosion in soils is a major concern, especially as much of the buried
infrastructure is aging. Increasingly stringent environmental protection
requirements are also bringing corrosion issues to the forefront for
many systems either buried or aboveground and possibly in contact

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