Onset of Microbial Influenced Corrosion (MIC) in Stainless Steel Exposed to Mixed Species Biofilms from Equatorial Seawater

Abstract

19The understanding of microbial influenced corrosion (MIC) in aerobic mixed biofilms 20 benefits from advanced microscopy and microbial ecology characterization of biofilms. Here, 21 the onset of MIC in stainless steel coupons was studied in both natural and artificial seawater. 22 Rapid selection of biofilm-forming microorganisms from natural seawater was observed for 23 field experiments. Potential ennoblement was observed only in natural seawater. A seawater 24 derived mixed microbial consortium enriched in artificial seawater was used to characterize 25 the effect of several parameters on MIC. The concentration of organic carbon was the major 26 determinant of MIC, while shaking speed and polishing played minor roles. The biofilm was 27 preferentially formed at the grain boundaries. These results outline the need for MIC onset 28 characterization with mixed microbial consortia to predict long-term corrosion behaviour of 29 stainless steel in seawater. 30 31 Introduction 32Microbially influenced corrosion (MIC) of metals refers to the involvement of 33 microorganisms in the metal deterioration process. MIC has significant economic 34 consequences for industries such as oil and gas, mining, logistics and waste water treatment, 35 with social and environmental impacts associated with the deterioration of materials 1 . 36 2 Microorganisms affect physicochemical reactions at the metal/liquid interface, either slowing 37 down or accelerating abiotic corrosion processes 1, 2 . Due to their physicochemical 3 and 38 microbiological resistance 4 to metal deterioration and MIC, stainless steels (SS) are used in 39 key marine components. 40 41 MIC mechanisms previously put forth include the effects of differential concentrations of 42 oxygen and nutrients; generation of corrosive metabolites or by-products; alteration of anion 43 ratios and inactivation of corrosion inhibitors 5 . Adsorbed extracellular biofilm matrix 44 molecules such as proteins, lipids, humic acids and polysaccharides change the SS surface by 45 modifying surface charge, wettability or surface energy, thus enhancing or inhibiting MIC 6 . 46The biofilm can also act as a diffusional barrier preventing oxygen and corrosive substances 47 from reaching the metal surface 7 . 48 49 Sulphate-reducing bacteria (SRB) are commonly cited as the primary organisms responsible 50 for MIC under anaerobic and anoxic conditions in seawater through the production of 51 corrosive sulphides. However, aerobic microorganisms have also been increasingly studied, 52 substantiating their role in MIC process. For example, in the presence of the aerobic marine 53 bacterium Pseudomonas sp., SS304 showed a higher corrosion rate and lower resistance of 54 the passive film, indicating localised breakdown of passive film, in contrast with abiotic 55 experiments with stable and passivating Cr-enriched oxide films 8 . Microbial activities can 56 alter the inorganic passive layer and increase metal dissolution. Extensive micro-pitting 57 corrosion was observed underneath biofilms...

A Review of Characterization and Quantification Tools for Microbiologically Influenced Corrosion in the Oil and Gas Industry: Current and Future Trends

“…A study of aerobic copper corrosion revealed a lower charge transfer resistance in a biotic environment possibly due to breakdown of the passive film by microbiological action . Additionally, aerobic environments may undergo transformation into local anaerobic cells, due to the rapid microbiological growth which scavenges the oxygen . Aggressive pitting-type corrosion accelerated by the presence of aerobic P. aeruginosa biofilms has been found to accelerate corrosion of carbon, duplex, and 304 stainless steels. ,− …”

“…154 Additionally, aerobic environments may undergo transformation into local anaerobic cells, due to the rapid microbiological growth which scavenges the oxygen. 155 Aggressive pitting-type corrosion accelerated by the presence of aerobic P. aeruginosa biofilms has been found to accelerate corrosion of carbon, duplex, and 304 stainless steels. 65,156−158 Due to a large volume of bench scale investigation of MIC, the surface preparation of substrates is important for reproducibility of results, since the area of attachment of the bacteria can be influenced by the underlying microstructure.…”

Effect of pH regulation by sulfate-reducing bacteria on corrosion behaviour of duplex stainless steel 2205 in acidic artificial seawater

“…The previous report has indicated that environmental pH has significant effect on the corrosion of materials not only in the abiotic environment [11][12][13][14][15], but also in the microbial environment [16][17][18]. However, the recent literature has focused mostly on MIC behaviour of duplex stainless steel at a neutral pH [19][20][21][22]. Corrosion on stainless steel caused by SRB in different pH environments has received less attention.…”

Carbon Source Starvation of a Sulfate-Reducing Bacterium–Elevated MIC Deterioration of Tensile Strength and Strain of X80 Pipeline Steel

“…Sulfate-reducing bacteria (SRB) are the most ubiquitous microorganisms in anaerobic environments, and they are the most important microbes in MIC (microbiologically influenced corrosion) in the oil and gas systems which are mostly anaerobic and often involve seawater containing sulfate (Little and Lee, 2007;Sheng et al, 2007;Xu et al, 2016;Jia et al, 2017;Jogdeo et al, 2017). SRB MIC can induce mechanical degradations of metallic materials (Abedi et al, 2007;AlAbbas et al, 2013;Al-Nabulsi et al, 2015;Wu et al, 2015).…”