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ment corrosion, shutdown of plants due to replacement of
corroded equipment, impurity in processed products due
to corrosion as well as waste of the products of those
vessels which are attacked by corrosion. The report indi-
cates that about 70 percent of losses can be prevented by
observing related principles and instructions.
One of the main problems in oil and gas industries is
corrosion of pipelines and other engineering structures.
This has always resulted in huge economic setback due
to large sum of money spent in trying to combat it. Based
on the forgoing, there is a great need to develop engi-
neering materials that are corrosion resistant to avoid
abrupt failure of the engineering structures.
Recently, the corrosion characteristics of selected fer-
rous metal samples (plain and alloyed ductile iron, low
carbon steel and austenitic stainless steel) in crude oil
were investigated by using weight loss method [5]. Stud-
ies carried out during this work show that all the materi-
als experience gain in weight within the first 10 days in
the medium. This weight gain is attributed to the forma-
tion of hard and passive phases which acted as strong
protective barriers to corrosion. It was also observed that
the rate of corrosion decreased with increase in the num-
ber of days of exposure for all the coupons, this may be
probably due to the deposition of corrosion products that
tend to shield the corroding surface from further corro-
sion attack, thereby depressing the rate of corrosion. This
result shows that despite of initial low corrosion resis-
tance of plain ductile iron, it can still be considered,
alongside other materials, for application in pipelines and
storage facilities for crude oil.
Studies [6] on the corrosion behaviour of carbon steel
under natural and stagnant seawater conditions have
showed that the alloy is more corrosive in anaerobic stag-
nant sea-water conditions than that in aerobic conditions.
The study also revealed that in both aerobic and anaero-
bic exposures, corrosion was more aggressive on hori-
zontally oriented coupons compared to vertically orient-
ed samples.
The corrosion behaviour of low carbon steel has also
been investigated [7] in natural seawater and various
synthetic seawaters. It was found that the steel corroded
nearly four times faster in a 3.5% NaCl solution than in
natural seawater for an exposure time of 21 days. The
corrosion rate after immersion in synthetic seawaters was
found to be similar to the corrosion rate after immersion
in natural seawater. Calcium carbonate (aragonite) de-
posits were found on the surface of the steel after immer-
sion in natural seawater and the synthetic seawaters.
Some magnesium-containing deposits were also found
after immersion in the natural seawater. These deposits
act as a barrier against oxygen diffusion and thereby
lower the corrosion rate. The morphology of the calcium
carbonate deposits that formed during immersion in the
natural seawater was found to be different from those
formed during immersion in the solution.
It has been shown [8] that MnAl6 formed from Al and
Mn has almost the same electrode potential as aluminium
and this compound is capable of dissolving iron which
reduces the detrimental effect of Mn. Commercial Al-Mn
alloys contains up to 1.25% manganese although the
maximum solid solubility of this element in aluminium is
as high as 1.82%. This limitation was imposed because
the presence of iron as impurity reduces the solubility
and there is a danger that large primary particles of
MnAl6 will form with a disastrous effect on local ductil-
ity.
Polmear [8] reported that Al-Mn alloys belong to the
3xxx series of alloys which are used for the manufacture
of roofing sheets. These sheets are subject to corrosion
because of the presence of moisture and oxygen in the
atmosphere. The corrosion of this alloy is due to the
strong affinity aluminium has for oxygen which results to
its oxidation and subsequent formation of oxide film.
Ekuma et al. [9] reported that with time, this film be-
comes passive to further oxidation and stable in aqueous
media when the pH is between 4.0 and 8.5. It is impor-
tant to state that the passive films can break and fall off,
hence exposing the surface of the alloy to further corro-
sion.
Studies [4] on corrosion management indicate that it
offers preventive strategies in two technical and non-
technical domains. Technical domains as preventive
strategies are highly important. These includes: 1) Up-
grading planning methods and using advanced planning
ones to better corrosion management and so prevent
avoidable corrosion costs. In this vein, planning methods
must change and the best corrosion technologies must be
available for planners. 2) Improving corrosion technolo-
gies via research and development. Corrosion can be
controlled in most industries by using scientific methods
and new technological achievements.
Non-technical domain as preventive strategies includes:
1) Enhancing the employees' awareness about the high
costs of corrosion and saving costs result in correct ap-
plication of existing technologies and corrosion costs.
Thus a lot of corrosion problems are due to lack of
awareness about corrosion management and accountabil-
ity of people in exchanging operations, inspection and
maintenance of management system. 2) Changing guide-
lines, protocols, standards and management methods to
reduce corrosion costs by correct corrosion management,
resulting in effective control of corrosion and safe opera-
tion and increase in shelf life of equipment. 3) Amend-
ing and generalization of employees’ instruction to in-
troduce and identify corrosion control. 4) Changing and
amending wrong belief about not being able to do any-
thing about corrosion and making new decisions in pre-
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