Due to the complex submarine environment, submarine pipeline steel often faces serious corrosion risk. Through potentiodynamic polarization technology and AC impedance technology, the effects of hydrostatic pressure, mass concentration of dissolved oxygen and growth days of sulfate reducing bacteria (SRB) on the electrochemical corrosion behavior of X70 pipeline steel in simulated solution in the South China Sea were investigated. Combined with electron microscope characterization technology, the corrosion morphology was analyzed, and the mechanism of the corrosion behavior of X70 steel under the coexistence of three environmental factors was clarified. The results show that the self corrosion current density of X70 pipeline steel in the experimental environment inoculated with SRB is twice that of sterile steel; under the pressure of 0~3.5 MPa, the corrosion degree first intensifies and then slows down; when SRB and dissolved oxygen coexist, the presence of oxygen inhibits the number of facultative anaerobic bacteria SRB, thus inhibiting corrosion.

Oil and gas pipelines (X52 steel) in the marine environment are highly susceptible to corrosion. The effects of different dissolved oxygen concentration, pH, and hydrostatic pressure on the corrosion behavior of X52 pipeline steel in the marine environment was analyzed using electrochemical testing technology and observation of corrosion morphology. The results show that the corrosion of the pipeline slowed down as the ambient pH increased, while the corrosion of the pipeline steel increased as the dissolved oxygen content and hydrostatic pressure increased. The corrosion behavior of pipeline steel under different conditions is controlled by anodic activation of dissolution, and all appear local pitting corrosion phenomenon.