Bacteria corrosive

Figure 4-459. Diagram of the bacterial corrosion of steel or iron by Desulfovibrio bacteria (corrosion products are underlined). (From Ref. [208].)...

Biofilm samples collected from carbon steel and concrete pipes of the DWSS Yovkovtsy had different appearance, content of water, organic and corrosion products, while ones from concrete pipe and water tank s surfaces were the same. Biofilm community mainly consisted of heterotrophic bacteria and some fungi, actinomyces and autotrophic bacteria. Corrosion related bacteria were determined in some of the biofilm samples. 

R. Javaherdashti. Behaviour of stainless steel316L in a marine mixed culture containing sulphate reducing and iron reducing bacteria. Corrosion Materials, Vol. 36, No. 2, pp. 52-57, 2011. 

E. Malard, D. Kervadec, O. Gil, Y. Lefevre, S.Malard. Interactions between steels and sulphide-producing bacteria—Corrosion of carbon steels and low-alloy steels in natural seawater. Electrochimica Acta,No. ... 

J.C. Earthman, W. Dang. Alternating magnetic field treatment of service water to control pitting induced by sulphate reducing bacteria. Corrosion Management, No. 96, pp. 11-14, 2010. 

Senez, J. C., "Investigation in Biological Corrosion in Anaerobic Soils by Sulfate-Reducing Bacteria, Corrosion and Anti-Corrosion, Vol. 1, 1953, pp. 131-132. 

Robinson, M. J. Kilgallon, P. J. Hydrogen embrittlement of cathodically protected high-strength, low alloy steels exposed to sulphate-redudng bacteria Corrosion 50 (1994) 8, p. 626-635... 

Hernandez G, Kucera V, Thierry D, Pedersen A, Hermansson M (1994) Corrosion Inhibition of Steel by Bacteria, CORROSION, 50(8) 603-608... 

J. L. Crolet, S. Daumas, and M. Magot, pH regulation by sulphate-reducing bacteria, CORROSION 93, New Orleans, paper 303, NACE, 1993. 

Caldwell DE, Wblfriaedt GM, Korber DR, Lawrence JR (1997) Do bacterial communities transcend Darwinism Adv Microb Ecol 15 105-191 Callow ME, Fletcher RL (1994) The influence of low surface energy materials on bioadhesion - a review. Int Biodeter Biodegr 34 333-348 Campaignolle X, Crolet J-L (1997) Method for studying stabilization of localized corrosion on carbon steel by sulfate-reducing bacteria. Corrosion 53 440-447... 

Hass H, Herfiirth E, Stoffler G, Redl B (1992) Purification, characterization and partial amino acid sequences of a xylanase produced by Penicillium chrysogenum. Biochim Biophys Acta 1117 279-286 Heisey RM, Papadatos S (1995) Isolation of microorganisms able to metabolize purified natural rubber. Appl Environ Microbiol 61 3092-3097 Hernandez G, Kucera V, Thierry D, Pedersen A, Hermansson M (1994) Corrosion inhibition of steel by bacteria. Corrosion 50 603-608 HespeU RB, O Bryan-Shah PJ (1988) Esterase activities in Butyrivihrio fibrisolvens strains. Appl Environ Microbiol 54 1917-1922 HiU EC (1987) Microbial problems in the off-shore oil industry. Institute of Petroleum, London, pp 25-28... 

The fluid is formulated from a premium mineral od-base stock that is blended with the required additive to provide antiwear, mst and corrosion resistance, oxidation stabdity, and resistance to bacteria or fungus. The formulated base stock is then emulsified with ca 40% water by volume to the desired viscosity. Unlike od-in-water emulsions the viscosity of this type of fluid is dependent on both the water content, the viscosity of the od, and the type of emulsifier utilized. If the water content of the invert emulsion decreases as a result of evaporation, the viscosity decreases likewise, an increase in water content causes an increase in the apparent viscosity of the invert emulsion at water contents near 50% by volume the fluid may become a viscous gel. A hydrauHc system using a water-in-od emulsion should be kept above the freezing point of water if the water phase does not contain an antifreeze. Even if freezing does not occur at low temperatures, the emulsion may thicken, or break apart with subsequent dysfunction of the hydrauHc system. 

Various patents (22—24) have been issued claiming the use of tetrakis(hydroxymethyl)phosphonium sulfate in, for example, water treating, pharmaceuticals (qv), and in the oil industry where this compound shows exceptional activity toward the sulfate-reducing bacteria that are a primary cause of hydrogen sulfide formation and consequent problems associated with souring and corrosion (25). 

The manner in which many of these bacteria cany on their chemical processes is qmte comphcated and in some cases not fuUy understood. The role of sulfate-reducing bacteria (anaerobic) in promoting corrosion has been extensively investigated. The sulfates in shghtly acid to alkaline (pH 6 to 9) soils are reduced by these bacteria to form calcium sulfide and hydrogen sulfide. When these compounds come in contact with underground iron pipes, conversion of the iron to iron sulfide occurs. As these bacieria thrive under these conditions, they will continue to promote this reaction until failure of the pipe occurs. 

Waters While MIC-causing bacteria may arrive at the surface of their corrosion worksite by almost any transportation system, there is always water present to allow them to become ac tive and cause MIC to occur. There are plenty of examples of even superpure waters having sufficient microorganisms present to feed, divide, and multiply when even the smallest trace of a viable food-stuff is present (e.g., the so-called watei for injection in the pharmaceutical industiy has been the observed subject of extensive corrosion of pohshed stainless steel tanks, piping, and so on). 

Occasionally corrosive bacteria may colonize crevices. Although rare compared to ordinary crevice attack, microbiologically influenced... 

Four main kinds of bacteria have been linked to accelerated corrosion in cooling water systems ... 

Sulfate reducers. The best-known form of microbiologically influenced corrosion involves sulfate-reducing bacteria.- Without question, sulfate reducers cause most localized industrial cooling water corrosion associated with bacteria. Desulfovibrio, Desulfomonas, and Desulfotomacu-lum are three genera of sulfate-reducing bacteria. 

Acid producers. Many bacteria produce acids. Acids may be organic or inorganic depending on the specific bacterium. In either case, the acids produced lower the pH, usually accelerating attack. Although many kinds of bacteria may generate acids, Thiobacillus thiooxidans and Clostridium species have most often been linked to accelerated corrosion on steel. 

Thiobacillus thiooxidans is an aerobic organism that oxidizes various sulfur-containing compounds to form sulfuric acid. These bacteria are sometimes found near the tops of tubercles (see Chap. 3, Tubercu-lation ). There is a symbiotic relationship between Thiobacillus and sulfate reducers Thiobacillus oxidizes sulfide to sulfate, whereas the sulfate reducers convert sulfide to sulfate. It is unclear to what extent Thiobacillus directly influences corrosion processes inside tubercles. It is more likely that they indirectly increase corrosion by accelerating sulfate-reducer activity deep in the tubercles. 

Clostridia are anaerobic bacteria that can produce organic acids. Short-chain organic acids can be quite aggressive to steel. Clostridia are frequently found deep beneath deposit and corrosion-product accumulations near corroding surfaces and within tubercles. Increased acidity directly contributes to wastage. 

Evidence of substantial deposition caused by Gallionella in tubercles is incomplete, however. The amount of such deposition is usually insignificant compared to the deposit and corrosion-product contribution that occurs in the absence of bacteria. 

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