Effect of Sulfate Reducing Bacteria from Corrosion Scale of Oil Pipeline on Corrosion Behavior of Q235 Steel

Sulfate reducing bacteria (SRB) from corrosion scale were cultured and the change trend of H₂S from the solution with SRB in the growth cycle was measured to prove whether the existence of SRB was the cause of increasing sulfur content in the oil pipeline. Corrosion coupon test and electrochemical experiment were used to research the corrosion behavior of Q235 steel in SRB and sterile mediums and the corrosion morphology and products of the steel were alalyzed. The results showed that there existed SRB in the oil pipeline and hydrogen sulfide gas was produced in the process of metabolism, which increased the possibility of stress corrosion cracking of pipeline steel. The corrosion mode on the surface of the steel was changed from the slight non-uniform corrosion to serious localized corrosion due to SRB. The metabolites of SRB were mainly sulfur compounds, and might be responsible for the increase of localized corrosion of the steel.