Accelerated sulfate reducing bacteria corrosion of X80 pipeline steel welded joints under organic carbon source starvation

Abstract

Sulfate-reducing bacteria (SRB) corrosion of X80 steel welded joint under organic carbon source starvation was investigated in the paper. The results showed that the number of planktonic cells is much less than that of sessile cells after 720 h immersion. The number of sessile cells in the base metal (BM) in the medium with 1% carbon source is the largest. Starving SRB cells accelerated simultaneously the uniform corrosion and localized corrosion of the welded joints, and the acceleration effect on the latter was much higher than that of the former. In all mediums, the density and average depth of pits in the BM and weld zone (WZ) were much larger than those in the heat affected zone (HAZ). SRB corrosion of the welded joint was strongly selective, and organic carbon source starvation further enhanced the selectivity.