Corrosion induced for a novel aerobic bacteria isolated in an offshore injection system

The results of a preliminary study of electrochemical noise (EN) measurements on API 5L X52 pipeline steel in the presence of aerobic bacteria are presented. The 16S rRNA gene sequence was used to identify the bacteria strain with high precision. The sequence analysis suggests that it may be a new bacterial species. The long-term noise time records show that, during the bacterial logarithmic growth stage, the pipeline steel generates irregular oscillations, typical of localized corrosion. while in the constant growth stage, the irregular oscillations diminish. Moreover, the long-term time records show that the noise patterns generated in a solution without bacteria were typical of a coupled mechanism of localized and uniform corrosion. Evidence was found that supports the EN measurements. Also, apparently the oscillations in current noise reach a regular pattern during the logarithmic growth phase. The statistical analysis of raw data shows that the trend of mean noise potential changes from a positive to a negative value in the presence of the bacteria. Compared to tests without bacteria, the noise resistance diminishes in the presence of the bacteria during the logarithmic growth stage. Finally, the localized parameter rises to near 1 during the stage when the metal undergoes localized corrosion.