The electrochemical noise technique was used to evaluate in static conditions the corrosion behavior of the API X52 and API X65 pipeline steels in natural seawater and seawater treated with several chemical products. The long-term current noise series in both pipeline steels show more perturbations in treated seawater compared to the coupons exposed in natural seawater. The electrochemical noise results have a good correlation with micrograph evidence of the corroded surfaces during the corrosion of API X52 and API X65 pipeline steels. The micrograph evidence suggests that at PI (pitting index, defined as the standard deviation of the electrochemical current noise divided by root mean square of the coupling current) mean value near to 1 the localized corrosion is most severe. The presence of bacterial consortia influences the trend of the PI values at the interval of 0.01-0.1, after 35 hours.
Keywords: electrochemical noise, microbiological induced corrosion, environmental scanning electron microscopy, bacteria consortia, seawater.