Microbiologically Induced Corrosion MIC

Microbiological corrosion in the process industries is most often found in three areas cooling water systems, aqueous waste treatment, and gronndwater left in new equipment or piping systems after testing. Nearly all confirmed cases of MIC have been accompanied by characteristic deposits. These are usually discrete mounds. Deposit color can also be an indication of the types of micro-organisnis that are active in the system. For example, iron bacteria deposits on stainless steel, such as those produced by Gallionella, are often reddish. 

Investigators have shown that in almost all cases the environment causing the damage was natural, essentially untreated water containing one or more culprit species of microbiological organisms. In the case of austenitic stainless steel weldments, corrosion generated by bacteria takes a distinctive form, that is, sub-surface cavities with only minute pinhole penetration at the surface. 

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Seawater-based utility systems for condenser and process cooling systems in power plants exhibit serious corrosion, erosion and fouling problems. Equipment made from carbon steel and even stainless steel shows sign of degradation from galvanic effect, corrosion, erosion and microbiological induced corrosion (MIC). Corrosion... 

Microbiologically induced corrosion (MIC). MIC is caused by the activity of SRB. SRB are anaerobic bacteria that reduce sulfates to form sulfides. The rate of conversion of sulfate to sulfide is very high and may lead to a high corrosion rate, especially in the areas in which the iron sulfide film is damaged. 

The presence of some forms of aerobic or anaerobic bacteria promotes corrosion, called microbiologically induced corrosion (MIC). The most common type of bacteria causing corrosion in soil is anaerobic sulfate reducing bacteria (SRB). Bacteria can cause the corrosion of ferrous and non-ferrous pipe. Identification and measurement of MIC can be accomplished by either laboratory analysis or by using several commercially available test kits. 

R.A. King. Trends and developments in microbiologically induced corrosion in the oil and gas industry. In the Proceedings of MIC—An International Perspective Symposium, Extiin Corrosion Consultants, Curtin University, Perth, Australia, 2007. 

King RA (2007) Microbiologically induced corrosion and biofihn interactions. MIC - An International Perspective Symposium. Extrin Corrosion Consultants, Curtin University, Perth, Austiaha, 14—15 Fehruary 2007... 

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