Pitting corrosion microbiologically influenced

The black scale was carefully removed to identify the morphology of pits (Figure 7.60). The pits were located at the bottom of a hole (Figure 7.61). The morphology of the pits is characteristic of microbiologically influenced corrosion (MIC). 

Fig. 7.1 Examples of pitting corrosion, (a) Pitting and subsequent cracking in a chromium-plated copper sink-drain trap, (b) Pitting in a stainless steel thermos-bottle liner, (c) Pitting in a brass condensate line, (d) Mounds (or tubercles) associated with microbiologically influenced corrosion of atype 304 stainless steel pipe used for untreated fresh water. Underlying pits completely penetrate the wall thickness.

Some areas in the pipe showed the presence of both green deposits and shiny copper (Fig. 5.53). Pits were present in areas where copper is surrounded by green deposits (Fig. 5.54). The green deposits indicate significant corrosion. The black scale was carefully removed to identify the morphology of the pits (Fig. 5.55). The pits were located at the bottom of a hole. The morphology of the pits appeared to be characteristic of microbiologically influenced corrosion (Fig. 5.56). 

The first chapter constitutes an introduction to corrosion and various forms of corrosion such as general or uniform or quasi-uniform corrosion, galvanic corrosion, stray current corrosion, localized corrosion, such as pitting and crevice corrosion, metallurgically influenced and microbiologically influenced corrosion, mechanically assisted corrosion and environmentally induced cracking. 

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. 

In aqueous environments, microorganisms may influence the electrochemical environment and, consequently, corrosion rates and/or the susceptibility of metals to localized pitting corrosion in several ways. However, aU known cases of microbiologically influenced corrosion of metals can be attributed to known corrosion mechanisms, which are briefly summarized below. 

Al-Darhi MM, Agha K, Islam MR (2005) Modeling and simulation of the pitting microbiologically influenced corrosion in different industrial systems. Paper 05505, CORROSION 2005, NACE International, Houston, Texas USA... 

Microbiologically influenced corrosion Visual, leakage testing Pitting corrosion... 

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