A Predictive Model on Pipeline Corrosion

Abstract

A comprehensive mathematical model is developed to predict corrosion rates in pipeline. The specimen
used for this design is coupons (mild steel). Four containers with different solvents of 0.5 concentration
of nitric acids, 0.5 concentration of HCl, fresh water, and saltwater respectively were provided, and
the four paired coupons were placed inside the solvent for seven days. Each day, the coupons were
removed, washed, dried, weighed, and placed back into the solvent. The result obtained shows the effect
of duration of corrosion operation on corrosion rate. On a logarithms scale, as the time increases, the
rate of corrosion remains approximately constant until a certain point (at t = 120 minutes) when the
corrosion reduced drastically. This implies corrosion of the process is not supported when time is
greater than 120 minutes. The graph depicts a real-life situation when the corrosion rate will always
remain constant and deplete when the condition is not satisfactory for corrosion to take place. Similarly,
on the relationship between the corrosion rates with time at different pressure, the corrosion rate is
approximately constant with increase in duration, up to a certain point where it drastically reduced.
Furthermore, on the effect of pressure in the corrosion, the pressure is directly proportional to
corrosion rate. That is, as the pressure reduces, from 5 atm to 0.5 atm, there is an approximately
positive correlation reduction in the corrosion rate from 0.82 to 0.45. This also implies that, an increase
in the pressure will cause a corresponding increase in the corrosion rate.