Corrosion potential microbiologically influenced

A perforation in similar piping was caused by wastage beneath a tubercle. Although potentially aggressive bacteria were present in this system, no evidence of microbiologically influenced corrosion was found on this section. 

By such a simple system, the potential with time can be measured. The equilibrium potential (Usually, it is called mixed potential, since plural potentials are balanced at a value.) often shows a certain tendency. For example, the specimen s mixed potential generally moves in the noble direction, when the microbiologically influenced corrosion occurs. In such a case, only the potential measurement would provide us sufficient information to some extent... 

The changes in jet fuel and jet fuel additives that have taken place in recent years have also brought about a shift in the microbial community in aircraft fuel. The bacteria isolated from aircraft jet fuel tanks have been found to be closely related to Bacillus, and they do have the potential to cause microbiologically influenced corrosion (MIC) [11,17,18]. 

LOUTHAN, M.R., Jr., The potential for microbiologically influenced corrosion in the Savannah River spent fuel storage pools , Proc. NATO Workshop on Microbial Degradation Processes in Radioactive Waste Repositories and in Nuclear Fuel Storage Areas, Budapest, 1996, Kluwer, Dordrecht (1997). 

Zhang, H. J. and Dexter, S. C., Effect of Biofilms on Critical Pitting Potentials for Stainless Steels S30400 and S31600 in Seawater, International Conference on Microbiologically Influenced Corrosion, P. Angell, Ed., NACE International, Houston, TX, 1995, pp. 70-71. 

Microbiologically Influenced Corrosion Modeling and Simulation of Biosensors Spectroelectrochemistry, Potential of Combining Electrochemistry and Spectroscopy... 

The presence of a biofilm on a metallic surface can greatly alter the local corrosion processes. In addition to the electrochemical changes that directly affect corrosion, biofilms can also modify other readily measured characteristics such as pressure drop or heat transfer resistance. Monitoring such microbiological influences can provide a useful indicator that a biofilm is present and that action should be taken to mitigate potential MIC. 

More recently, attention has been directed to the "ninth form of corrosion, biologically influenced corrosion, which includes studies on an area referred to as "ennoblement. The presence of biofilms on metals and alloys immersed in natural seawater produces a complex, heterogeneous chemistry along the metallic surface. It has usually been observed that passive alloys such as aluminum, stainless steels, nickel-base alloys, or titanium show an increase to more noble (electropositive) potentials or ennoblement of several hundred millivolts with exposure time in natural seawater, thus magnifying the potential differences that may exist between dissimilar alloys [26,55-64]. Ennoblement is likely caused by the formation of microbiological films, which increase the kinetics of the cathodic reaction [55-63],... 

Several variables are known to have an influence on corrosion rates in soil these include water, degree of aeration, pH, redox potential, resistivity, soluble ionic species (salts), and microbiological activity. The complex nature of selected variables is presented graphically in Fig. 10.2 [2]. 

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