Stress corrosion cracking behavior induced by Sulfate-reducing bacteria and cathodic protection on X80 pipeline steel

Abstract

Oil and gas pipelines with cathodic protection (CP) are often affected by Sulfate-reducing Bacteria (SRB), so it is of great relevance to understand the effect of SRB and CP potentials on the stress corrosion cracking (SCC) behavior of pipeline steel. In this paper, the SCC mechanisms in SRB-inoculated and sterile near-neutral soil environments were investigated at different CP potentials. Electrochemical tests and slow strain rate tensile tests showed that at −850 mV the pipeline steel was in a cathodic protected state. At −1000 mV and −1200 mV, strong cathodic polarization promotes the hydrogen evolution reaction, while SRB not only promotes pitting to provide a basis for crack nucleation, but also has a poisoning effect. The results show that the strong cathodic polarization potential and SRB increase the SCC susceptibility of pipeline steel and the hydrogen embrittlement (HE) risk.