Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers


Microbial Corrosion

Last updated: August 15, 2019

What Does Microbial Corrosion Mean?

Microbial corrosion is the corrosion brought about by the activities and presence of microbes. This occurs in several forms and can be managed by traditional control methods and biocides.

This process of degeneration chiefly acts on metalloids, metals and rock-based matter. Apart from bacteria, microbial corrosion can also be influenced by micro algae, inorganic and organic chemicals. This form of corrosion affects entities like power plants and chemical industries, as well as facilities that make use of cooling towers.

Microbial corrosion is also known as microbiologically-influenced corrosion (MIC).


Corrosionpedia Explains Microbial Corrosion

Biological organisms influence this type of corrosion. This influence usually results in a substantially faster corrosion rate. It affects almost all types of alloys like stainless, ductile iron and copper, but not titanium. The effect differs among alloys—steel corrodes faster than ductile iron.

Microbial corrosion is not caused by one microbe, but can be attributed to several microbes. These are usually grouped by main characteristics like the effect on compounds and byproducts. In general, the microbes responsible for microbial corrosion can be categorized in two groups according to oxygen requirements:

  • Aerobic (needing oxygen): like bacteria capable of sulfur oxidizing
  • Anaerobic (needing no or little oxygen): like bacteria that are sulfate reducing

Almost all microbial corrosion takes the appearance of pits forming underneath living matter colonies, minerals, and bio deposits. This results in a biofilm that results in a confined environment where the conditions can be corrosive. This, in turn, hastens the corrosion process.

The development of microbial corrosion happens in three stages:

  1. Microbe attachment
  2. Growth of initial pit and nodule
  3. Maturation of nodule and pit

Microbial corrosion can be a severe problem in inactive water systems. Utilizing mechanical cleaning techniques and biocides can lessen microbial corrosion. However, any area collecting stagnant water is very susceptible to microbial corrosion.

Furthermore, microorganisms that are capable of utilizing hydrocarbons like pseudomonas aeruginosa can be found in aviation fuel. This forms dark brown or green mats similar to a gel, and leads to microbial corrosion on the rubber and plastic parts of the fuel system of an aircraft.




microbiologically-influenced corrosion (MIC)

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