Microbiologically Influenced Corrosion of Carbon Steel in Sea and Effluent Water Injection Plants of North and West Kuwait Oil Fields

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The Electrochemical noise (EN) technique was used successfully to analyse, evaluate, and monitor microbiologically influenced corrosion (MIC) of carbon steel (CS) in stagnant seawater with and without aerobic bacteria, biocides and inhibitors at different temperatures and pH values. It was also used to increase understanding of how MIC initiates and advances in CS seawater. The EN results matched those obtained with scanning electron microscopy (SEM). The results indicated that the corrosion rate of CS in seawater with a pH of 8.25 increased with temperature in the presence of aerobic bacteria, and decreased slightly with increasing the temperature in the presence of aerobic bacteria, biocides and inhibitors. With the blank test, the corrosion rate increased with temperature in the first and last 20 d, but in between, there were only minor changes in the corrosion rate. At a pH of 6, the corrosion rates for CS seawater increased with increasing the temperature in all tests. The corrosion rates of CS in blank seawater at 37ºC with pHs of 6 and 8.25 were similar, while there was a noticeable change at 45ºC: the corrosion rates increased with increasing pH values. When CS was exposed to seawater with aerobic bacteria, the corrosion rate at 37ºC and pHs 6 and 8.25 were also similar, while there was a noticeable change at 45ºC: the corrosion rate increased with increasing pHs for CS exposed to seawater with aerobic bacteria, biocides and inhibitors, the corrosion rate at a pH of 6 was lower at 37ºC, and at a pH of 8 it was lower at 45ºC.