Micro biologically-Influenced Corrosion (MIC), also known as microbial corrosion or biological corrosion is the deterioration of metals as a result of the metabolic activity of microorganisms.
There are about a dozen of bacteria known to cause micro biologically influenced corrosion of carbon steels, stainless steels, aluminum alloys and copper alloys in waters and soils with pH 4~9 and temperature 10oC~50oC.
These bacteria can be broadly classified as aerobic (requires oxygen to become active) or anaerobic (oxygen is toxic to the bacteria). Sulphate reducing bacteria (SRB) is anaerobic and is responsible for most instances of accelerated corrosion damages to ships and offshore steel structures. Iron and manganese oxidizing bacteria are aerobic and are frequently associated with accelerated pitting attacks on stainless steels at welds.
Many industries are affected by MIC:
Chemical processing industries: stainless steel tanks, pipelines and flanged joints, particularly in welded areas after hydro testing with Natural River or well waters.
Nuclear power generation: carbon and stainless steel piping and tanks; copper-nickel, stainless, brass and aluminum bronze cooling water pipes and tubes, especially during construction, hydrotest, and outage periods.
Onshore and offshore oil and gas industries: mothballed and waterflood systems; oil and gas handling systems, particularly in those environments soured by sulfate reducing bacteria (SRB)-produced sulfides
Underground pipeline industry: water-saturated clay-type soils of near-neutral pH with decaying organic matter and a source of SRB.
Water treatment industry: heat exchangers and piping
Sewage handling and treatment industry: concrete and reinforced concrete structures
Highway maintenance industry: culvert piping
Aviation industry: aluminum integral wing tanks and fuel storage tanks
Metal working industry: increased wear from breakdown of machining oils and emulsions
Marine and shipping industry: accelerated damage to ships and barge
Micro biologically influenced corrosion is caused by specific genera of bacteria which feed on nutrients and other elements found in waters and soils. Sea water is a primary source of sulphate reducing bacteria (SRB). The biological activities modify the local chemistry (acid-producing) and render it more corrosive to the metals. For example, iron-oxidizing bacteria can perforate a 5mm thick 316 stainless steel tank in just over a month.
Micro biologically influenced corrosion, or microbial corrosion or biological corrosion can be prevented through a number of methods:
Regular mechanical cleaning if possible
Chemical treatment with biocides to control the population of bacteria
Complete drainage and dry-storage
These bacteria can be broadly classified as aerobic (requires oxygen to become active) or anaerobic (oxygen is toxic to the bacteria). Sulphate reducing bacteria (SRB) is anaerobic and is responsible for most instances of accelerated corrosion damages to ships and offshore steel structures. Iron and manganese oxidizing bacteria are aerobic and are frequently associated with accelerated pitting attacks on stainless steels at welds.
Many industries are affected by MIC:
Chemical processing industries: stainless steel tanks, pipelines and flanged joints, particularly in welded areas after hydro testing with Natural River or well waters.
Nuclear power generation: carbon and stainless steel piping and tanks; copper-nickel, stainless, brass and aluminum bronze cooling water pipes and tubes, especially during construction, hydrotest, and outage periods.
Onshore and offshore oil and gas industries: mothballed and waterflood systems; oil and gas handling systems, particularly in those environments soured by sulfate reducing bacteria (SRB)-produced sulfides
Underground pipeline industry: water-saturated clay-type soils of near-neutral pH with decaying organic matter and a source of SRB.
Water treatment industry: heat exchangers and piping
Sewage handling and treatment industry: concrete and reinforced concrete structures
Highway maintenance industry: culvert piping
Aviation industry: aluminum integral wing tanks and fuel storage tanks
Metal working industry: increased wear from breakdown of machining oils and emulsions
Marine and shipping industry: accelerated damage to ships and barge
Micro biologically influenced corrosion is caused by specific genera of bacteria which feed on nutrients and other elements found in waters and soils. Sea water is a primary source of sulphate reducing bacteria (SRB). The biological activities modify the local chemistry (acid-producing) and render it more corrosive to the metals. For example, iron-oxidizing bacteria can perforate a 5mm thick 316 stainless steel tank in just over a month.
Micro biologically influenced corrosion, or microbial corrosion or biological corrosion can be prevented through a number of methods:
Regular mechanical cleaning if possible
Chemical treatment with biocides to control the population of bacteria
Complete drainage and dry-storage
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