The effect of cathodic polarization on the corrosion behavior of X65 steel in seawater containing sulfate‐reducing bacteria

Abstract

Sulfate-reducing bacteria (SRB) are one of the main reasons for the accelerated corrosion of steel. Cathodic polarization has been reported as an effective and economic method against marine corrosion, including microbiologically induced corrosion. However, the interaction between cathodic polarization and microbial activity has not been well defined. In this study, a fluorine-doped tin oxide electrode is used to study the effect of cathodic current on SRB cells. Fluorescence microscopy results clearly show that the attachment degree of SRB is dependent on the electric quantity and current intensity. The large electric quantity and high cathodic current (400 mA/m 2 × 30 h) can effectively inhibit bacterial attachment and subsequent biofilm formation. Furthermore, the effect of cathodic potential on the corrosion behavior of X65 steel in the presence of SRB is systematically investigated. Results show that the impressed charges, the increase of pH, and the formation of calcareous deposits on the electrode surface at the cathodic potential of −1,050 mV/SCE inhibit the attachment of SRB. In turn, the presence of SRB also interferes with the electrochemical reactions that occur during the polarization process, thus increasing the cathodic current. The interaction between SRB-induced corrosion and the process of preventing corrosion by various cathodic potentials is discussed.

Role of Fe oxide in the underdeposit corrosion of pipeline steel in oilfield produced water containing SRB

“…The Fe 2p spectra of the compounds detected in the corrosion products of the Fe oxide deposited steel (Figure 9a,c) includes FeO, FeOOH, Fe 3 O 4 , and FeS at 708.1, 724.3, 710.4, and 713.6 eV respectively. [ 35,36 ] The S 2p spectra indicate that the steel under Fe oxide (Figure 9c) contained more FeS (at 160.9 eV) than the sand‐deposited sample. [ 36 ] Notably, FeS 2 (at 162.4 eV) was not detected in the corrosion product of the Fe oxide deposited steel (Figure 9c,d), suggesting the transformation of some sulfide species in the deposit.…”

“…[ 35,36 ] The S 2p spectra indicate that the steel under Fe oxide (Figure 9c) contained more FeS (at 160.9 eV) than the sand‐deposited sample. [ 36 ] Notably, FeS 2 (at 162.4 eV) was not detected in the corrosion product of the Fe oxide deposited steel (Figure 9c,d), suggesting the transformation of some sulfide species in the deposit. [ 36–38 ]…”

Effects of cathodic protection potential on microbiologically induced corrosion behavior of X70 steel in a near-neutral pH solution

“…The hydrogen evolution potential of X70 steel in the medium moved positively compared with that in sterile solution, indicating that the concentration of H + in the bacterial medium was much higher than that in the sterile solution. In most studies on SRB corrosion under cathodic protection [54,55], in the presence of bacteria, the cathodic protection current was larger and CP potential was more negative. However, opposite results were obtained in our study because the high concentrations of HCO 3 and CO 2 in NS4 solution were hydrolyzed to produce a large quantity of H + [56].…”

Effects of stress, strain rate and sulfate-reducing bacteria on corrosion behavior of X70 pipeline steel

“…Chen et al (2021aChen et al ( , 2021bChen et al ( , 2021c; Cui et al (2021aCui et al ( , 2020Cui et al ( , 2021b discovered that the metal corrosion rates in SRB-containing solutions were higher than that in the sterile solutions. According to Chen and Zhang (2018), Lv et al (2020), SRB interfered with the electrochemical reactions that happened during polarization, increasing the cathodic current. Chen et al (2021bChen et al ( , 2021c realized that as the strain rate increased, the rust layer was destroyed, resulting in a decrease in passive film resistance.…”