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700 South Industrial Way
Seattle, WA 98108

Forensic Engineering and Laboratories

Microbially Influenced Corrosion (MIC) Testing & Analysis

MDE's engineers and technical experts collaborate to offer microbiologically influenced corrosion (MIC) testing/analysis of residential, commercial, industrial, and fire protection water systems.   By offering testing and analysis experts under one roof, MDE's services are low cost with quick turnaround times. Our areas of expertise include:

MIC Testing and Analysis

  • Complete microbiologically influenced corrosion  (MIC) assessment
  • Water chemistry analysis to determine "aggressiveness" for a system's materials
  • MIC bacteria characterization and semi-quantitative analysis
  • Deposit / slime characterization

If microbiologically influenced corrosion is suspected due to observation of slime, restrictions in flow, or leaks/pinhole leaks in pipes, the testing for the presence of MIC is warranted to determine:

  • Whether bacteria related to MIC are present, and, if so, their relative concentration
  •  The extent of the corrosion present
  • The source of the corrosion
  • Limits of MIC affected system components

Metallurgical Evaluations of Pipes

  • Identify all forms of corrosion and/or mechanical degradation
  • Analysis of pinhole leak sites and turbercles
  • Field examinations
  • Destructive and non-destructive testing

Comprehensive Metallurgical Laboratory Analysis

  • Quality of materials
  • Quality of construction
  • Remaining pipe wall thickness evaluation
  • Piping system design and manufacturing quality assessment

Samples are collected in one of two manners.  MDE can collect the samples, on-site.  Alternately, MDE can send sample collection kits, including sterile bottles, for the customer to collect and overnight to MDE.  The MDE test kits include the required sterile containers for liquid or solids / slimes, and sampling instructions return shipping containers quick turnaround.  The liquid samples are cultured to determine the presence/absence of MIC related bacteria, and to semi-quantitate those types present.  Note that culturing the samples requires 16 days.
At the completion of the analysis, a peer reviewed analytical report is produced, including recommendations for corrective action, as appropriate.

Consultation Project Management and Mitigation Support

  • Recommendations from experts in the field
  • Technical expert consultation services
  • Additional services, as are warranted, by experts in mechanical systems, fire protection systems, metallurgical engineering, materials engineering, and related engineering.

Basic Information on MIC Testing of Fire Sprinkler Water

This testing can be performed for wet and dry systems.  Comprehensive testing is performed by collecting a number of samples at various locations in a system and sampling the make-up water.  Depending on the system configuration, visual observations, and problems experienced at the facility, sampling during one or more time intervals may also be appropriate.  The samples should be cultured on media for the presence (and relative concentration) of low nutrient bacteria, sulfate-reducing bacteria, iron-related bacteria, aerobic bacteria, anaerobic bacteria, low nutrient bacteria and acid producing bacteria.  Timely culturing of the samples is very important as MIC-related bacteria become dormant when the environmental conditions are altered.  Scaling or other chemical conditions in the water affect system corrosion and the interpretation of MIC sampling results; therefore, testing of the water for select chemical and physical properties of each sampling location and sampling interval is also useful.  The results of the water chemistry testing can also be beneficial in ascertaining how far advanced the corrosion is, as a result of deterioration from MIC-related bacteria.

Where leaks are present, appropriate sampling may also include metallurgical analysis of system components.  The metallurgical engineer analyzes the component using electron microscopes to ascertain the nature of all corrosion and failures present.

Microbiologically influenced corrosion, like other corrosion, causes degradation, deterioration and failures.  Understanding the causes, effects, and appropriate investigational methods is the first step in addressing MIC related problems.

Types of Bacteria Analyzed for MIC

  • Sulfate-Reducing Bacteria (SRB) – bacteria that converts sulfate ions to sulfides (including hydrogen sulfide).  These bacteria can grow in low oxygen environments.  SRB require sufficient organic nutrients.
  • Iron-Related Bacteria (IRB) – bacteria that converts soluble iron ions (ferrous) to insoluble iron ions (ferric).  The ferric iron is deposited on the piping or system surfaces, creating deposits that are host sites where other bacteria can grow.  These can be present in a wide variety of environmental conditions as they may be aerobic or anaerobic.
  • Low Nutrient Bacteria (LNB) – microbes/bacteria that grow in environments, such as potable water, with very low concentrations of nutrients.  LNB growth will form slimes and deposits which creates host sites where other MIC bacteria can grow.
  • Anaerobic Bacteria – bacteria that grow in the absence of abundant free oxygen.  These bacteria can grow in environments with as little as 50 parts per billion (ppb) dissolved oxygen.
  • Aerobic Bacteria – bacteria that grow in the presence of free oxygen.

Additional information, and recommendations for the number and location of samples for collection are available on request.