Tag: Corrosion in Tunnels

29Apr 2015

Combating Microbial Corrosion in Tunnels

By Robert Armstead

Microbial corrosion, or microbiologically-influenced corrosion (MIC), is “the gradual damage to metal caused by the metabolic activity of microorganisms.”  This corrosive damage has caused billons of dollars of damage to our water systems, especially our storm water and sewer systems, although MIC can happen wherever metal and water meet.  Finding a solution for repairing corrosive damage depends on where it is occurring, why it is occurring, and how disruptive or expensive a repair or replacement will be.

There are several different types of bacteria responsible for MIC in metals located in soils and water; all are classified as either aerobic (requires oxygen) or anaerobic (oxygen is toxic). Sulfate reducing bacteria (SRB) is anaerobic and is responsible for most of the corrosion caused to steel in sea water; whereas, iron and manganese oxidizing bacteria are aerobic and are most often responsible for the rapid corrosion and pitting at welds in stainless steel.  Microbial corrosion can also occur in plastics,…