Microbial corrosion behavior of pipeline steels in simulation environment of natural gas transportation pipeline

Abstract

Bacteria are introduced into natural gas transmission pipelines through water-driven gas extraction, which can exacerbate the occurrence of pipeline corrosion. This study utilized a micro-reactor to design a simulated corrosion environment that mimics natural gas gathering and transportation pipelines. The objective was to investigate the corrosion behavior of X80 pipeline steel under the combined effects of CO₂, Cl-, sulfate reducing bacteria (SRB), and iron bacteria (IOB). Additionally, it aimed to elucidate the influence mechanisms of these two microorganisms on corrosion. Under a humid environment with a total pressure of 8.5 MPa and a partial pressure of CO₂ at 0.85 MPa, the corrosion rate of X80 pipeline steel was observed to follow the sequence: IOB > control (asepsis) > SRB + IOB > SRB. During the initial stages of corrosion, highly active IOB becomes the primary factor contributing to corrosion. As corrosion progresses, the concentration of dissolved oxygen in the SRB system gradually decreases while SRB activity intensifies, leading to the formation of FeS through the process of corrosion. The corrosion current density (i_corr) exhibited a significant decrease, thereby intensifying localized corrosion of the corrosion products beneath the film. This resulted in a maximum pitting depth of 113.5 μm. Research on the behavior of microbial-enhanced corrosion provides significant guidance in the development and implementation of protective coatings.