under standing mic
DESCRIPTION
Under standing MICTRANSCRIPT
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UNDERSTANDING
MIC(Microbiologically Influenced Corrosion)
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• CORROSION DEFINITIONS
• WHAT IS MIC (Microbiologically Influenced Corrosion) • HOW TO IDENTIFY MIC
• HOW TO CONTROL MIC
• RUMORS RELATED TO MIC/DURO-SEAL
• DOES JOTUN’s DURO-SEAL SUPPORT OR PROPAGATE MIC
OVERVIEW
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CORROSION DEFINITIONS
• Corrosion requires four entities
- Anode
- Cathode
- Direct Metal Path
- Electrolyte
• Types of Corrosion
- General Corrosion
- Localized Pitting Corrosion
- Under Deposit Corrosion or Deposition (Anaerobic) Corrosion
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CORROSION WORKS SIMILARLY TO THEY WAY A BATTERY WORKS
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MIC FORMATION/DEGREDATION IS SIMILAR TO THE OPERATION OF AN AUTOMOTIVE BATTERY
1. The “Crusty Top Hat” (or outside Tubercle) is the frame or membrane that houses bacteria.2. The Direct Metal Path is the metallic connection of the cathodic area at the top of the pit to the anodic area at the pit bottom.3. The steel becomes the anode in lieu of lead storage plates and the sacrificial Positive anode. 4. The electrolyte is water and later as the micro-organisms form, is acid water (Sometimes sulphuric).
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WHAT IS MIC?
MIC is corrosion initiated or accelerated by microorganisms.
MIC is caused by specific genera of bacteria which feed on nutrients and other elements found in Fresh and Salt water.
It is generally understood that microorganisms (bacteria and fungi) are found living in almost every aqueous(water)environment on earth, but this does not mean that all species are directly or indirectly corrosive to steel.
Microorganisms require water to propagate (live)…
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NO WATER……..NO MIC CORROSION !
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TYPES OF MICROORGANISMS THAT PRODUCE MIC
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• Slime Formers
• Iron or Manganese Bacteria
• Sulfate-reducing Bacteria (SRB’s)
• Acid Producing Bacteria (APB’s-Aerobic or Facultative Anaerobic)
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SRB CORROSION
Pit Corrosion is not constant. In Barges where APB’s and SRB’s have been identified, some tanks and/or wet voids may have high levels of APB’s (Acid Producing Bacteria) whereas others may have high levels of SRB’s (Sulfate Reducing Bacteria). In either case, high levels of microbial activity are within the restricted confines of the crater. SRB’s frequently use the acidity of the APB’s as nutrient. Higher temperatures stimulate growth. “Crusty Top Hats” are usually found capping pit craters. Rates as high as 11 mm (430 mils or 0.433 inches) in one year have been found in certain instances.
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WHAT IS REQUIRED TO SUPPORT MIC (Microbiologically Influenced Corrosion)
Microorganisms are required to produce MIC.
Three requirements to produce microorganisms are:
• Microorganisms require water to propagate.
• Microorganisms require a food source to propagate.
• Microorganisms require specific environments to propagate such as water temperature and stagnant conditions.
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TWO OF THESE THREE ELEMENTS ARE CONTAINED IN RIVER WATER.
NO RIVER WATER….NO MIC CORROSION!
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MECHANISMS OF MIC
• Planktonic Bacteria• Inclusion and Receptor Sites• Sessile Bacteria• Synergistic Colony Formation• Nodules (Tubercles)• Pit Propagation
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Aerobic Bacteria(Pseudomonas Type)
Anaerobic Bacteria(Clostridium Type)
BACTERIA TYPES
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HOW TO IDENTIFY MICExperts need to use all three of the following confirmation tests to identify MIC.
Chemical-Test directly for pH, organic acids and test indirectly (test byproducts) for iron sulfide.
Biological-Several methods available. The most common are the MIC Field Kit and/or microbiological culturing. (Requires 28 days or more to produce results.)
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Metallurgical-Visually identify shiny metal underneath corrosion products.
MIC cannot be identified purely by use of a MIC Kit alone!
The cost of Proper inspections to identify MIC by MIC Experts can be can be $$Thousands$$ of Dollars Per Vessel!
KEEPING YOUR VOIDS CLEAN AND DRY WILL PREVENT MIC!
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This photo illustrates an area that has been cleaned and shows minimal general corrosion, intact mill scale, and intact coating. It also demonstrates rust staining over the intact coating. There is no evidence of MIC.
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IDENTIFYING MIC
Try to identify what this inspector is holding. Is it a MIC Tubercle?
What the inspector is holding is actually thought to be “river mud” and no MIC was present.
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WHO IS QUALIFIED TO TEST FOR MIC?
Personnel who have had formal training and experiencein the identification of the;
1. Chemical, 2. Biological, and3. Metallurgical,
should always perform testing for the characteristics of MIC.
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FIELD TESTS ALONE CANNOT CONFIRM MIC. LABORATORY TESTING MUST BE USED TO CONCLUDE MIC CORROSION DUE IN PART TO MICROBIOLOGICAL CULTURING PERIODS OF 28 DAYS OR MORE.
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Qualified barge inspectors use a wide range of instrumentsto obtain data during the inspections.
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(This is where it all started. Photo from FMT 3003)
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MINIMIZING MIC
• Routine inspections• Clean environment• Design of the barge• Barrier System• Chemical Treatments Through Green Chemistry• Maintain the Coating System• Other methods
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CONTROLLING MIC
• Dehydration And Clean environment.
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NO WATER-NO MIC CORROSION!
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RUMORS ABOUT MIC 1. MIC is new.
MIC is as old as steel itself and not new to the marine industry! Only the term MIC is new (derived in the early 1980’s) and was developed by the pipeline industry (and others) to specifically identify this phenomenon.
2. MIC is a bacteria.
MIC is not a bacteria. MIC is a corrosion mechanism formed by a very few specific types of microorganisms.
3. MIC is rampant in barges.
MIC is no more a phenomenon in barges than it is in waste water treatment systems, pipe lines and even sprinkler systems. General corrosion is often confused with MIC in barges.
4. Wherever there are microorganisms there is MIC.
Only a very few specific microorganisms are associated with MIC. These microorganisms must have water and be attached to the steel substrate to be harmful.
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5. Bacteria on steel prior to coating causes MIC.
Bacteria are everywhere. Bacteria on steel alone do not cause MIC. MIC is a corrosion mechanism that can take place only when the 3-criteria are met: Water, Food Source, and a Specific Environment. A sound film of properly applied intact coatings do not deter MIC.
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RUMORS ABOUT MIC AND DURO-SEAL
Duro-Seal with its Bee’s wax components have natural immunities to resist microbiological degradation. Duro-Seal does not support the MIC phenomenon as concluded by two separate independent laboratory studies.
6. Microorganisms can grow under intact coatings.Environmental conditions that exist under intact industrial coatings are
not suitable to sustain growth of microorganisms resulting in MIC.
7. MIC is in Duro-Seal.
Extensive testing by several world-class laboratories have proven there are no MIC producing microorganisms in Duro-Seal.
8. MIC eats Duro-Seal.
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RUMORS ABOUT DURO-SEAL
The water contained in Duro-Seal does not accumulate, it evaporates and dissipates during application and curing. Surveys conducted conclude that the source of water accumulating in barges is the result of condensation, rain water, river water, and/or seawater.
In addition, the “water” in Duro-Seal has “an added ingredient”. Used as a solvent for the wax, Duro-Seal uses Inhibited Ammonia to keep the wax from separating. This “added ingredient” doubles as a mild surface cleaner/disinfectant.
We all know that Inhibited Ammonia is an ANTIBACTERIAL and ANTIFUNGAL agent. If anything, the steel substrate is more free of microorganisms after the application of Duro-Seal than it is before application of Duro-Seal.
Duro-Seal also contains PROPOLIS-A natural antibacterial and antifungal used for sterilization in Beeswax.
9. Duro-Seal introduces water into voids.
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RUMORS ABOUT DURO-SEAL
Jotun Paints is the second largest marine coatings manufacturer in the world with 4,400 employees.
Our main research and development laboratory alone employs over 250 technical personnel.
10. Duro-Seal is the only barge coating Jotun manufactures.
Jotun manufactures a wide variety of coatings for barge internals and externals alike. These include a wide range of Inorganic (including waterborne) and Organic Zinc Primers, Epoxies & Surface Tolerant Epoxies, Alkyd, Acrylic Epoxy and Polyurethane Finishes.
11. Jotun Paints is a small specialty manufacturer.
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WHAT IS DURO-SEAL?
• Single Component Barrier Coat
• 35% solids (by volume), zero VOC
• Non flammable, fits safety requirements
• Environmentally benign
• Does not support microbial or bacterial growth
• Specifically designed as a void coating for the barge industry
• Intended as a cost effective corrosion barrier over minimum SP-2 prepared surfaces in voids
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NO.
OTHER QUESTIONS SPECIFICALLY ABOUT DURO-SEAL
1. What is the chemical composition of Duro-Seal? Duro-Seal is a water-borne coating made of principally Beeswax and other proprietary products.
2. Are there any petroleum-based products in Duro-Seal that could be used as a food source?
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YES. SOUTHWEST RESEARCH INSTITUTE RESEARCH REPORTS.
OTHER QUESTIONS SPECIFICALLY ABOUT DURO-SEAL
3. Is Beeswax resistant to microbial attacks in nature?
YES! BEESWAX CONTAINS PROPOLIS-A RESINOUS SUBSTANCE THAT IS ANTIMICROBIAL IN NATURE.
4. Is there any data to support Duro-Seal is resistant to microbial attacks?
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NO!
OTHER QUESTIONS SPECIFICALLY ABOUT DURO-SEAL5. What in-can Biocides are used in Duro-Seal?
NONE NEEDED. BEESWAX AND INHIBITED AMMONIA ARE ALL THAT ARE NEEDED AS PRESERVATIVES.
Furthermore, due to the strict requirements of Federal EPA, the addition of Man-Made Biocides are regulated and may be used in very limited quantities as a shelf-preservative. With this limitation, these small quantities will not be effective for the purpose of “killing MIC” in the dry film.
If quantities of Biocide are used to be effective against MIC, the product must be registered as a Pesticide. Worker Safety also becomes an issue.
6. What film preservatives are used in Duro-Seal?
NONE NEEDED. BEESWAX HAS HAS PROPOLIS AS ONE OF ITS NATURAL PRESERVATIVES!
7. Are there any sulfates in Duro-Seal?
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OTHER QUESTIONS SPECIFICALLY ABOUT DURO-SEAL
Duro-Seal is recommended for Dry Voids. Duro-Seal is not
recommended for Ballast Tanks. This is primarily due to: A. The minimal surface preparation of the surfaces to be coated. B. Duro-Seal’s low recommended film thickness for its intended application.
C. The design of the barge itself-no continuous welds.
8. What is the solubility of Duro-Seal in water?
Duro-Seal in highly soluble in the can or in liquid form.
Duro-Seal becomes highly insoluble when fully cured.
9. What is the performance of Duro-Seal in immersion service?
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DURO-SEAL TESTING IN A HUMIDITY CHAMBER
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DURO-SEAL EXPOSED TO SEAWATER
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Numerous tests for corrosion protection (including; salt fog exposure, humidity cabinet tests, microscopy, carbon long-chain degradation tests, etc.) have been performed by the following leading organizations.
Altran LaboratoriesJotun PaintsKTA TATORSouthwest Research Institute
Trinity Marine ProductsUniversity of Southern Mississippi
They concluded that Jotun Duro-Seal meets or exceeds the individual performance criteria in terms of corrosion resistance.
WHAT TESTING HAS BEEN PERFORMED ON DURO-SEAL?
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Numerous tests for resistance to microbiological attack (including: salt fog exposure, bubble test, humidity cabinet test, bacterial screening, bacterial exposure testing, microscopy, carbon long-chain degradation tests, etc.) have been performed by the following leading organizations.
Altran LaboratoriesJotun PaintsSouthwest Research Institute
THEY CONCLUDED THAT JOTUN DURO-SEAL DOES NOT
SUPPORT OR PROMOTE THE MIC PHENOMENON.
WHAT TESTING HAS BEEN PERFORMED ON DURO-SEAL?
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EXCERPTS FROM:
Evaluation of Possible Microbial Activity Leading toBarge Corrosion
FINAL REPORTSwRI TM Project 20.05444
Prepared forJotun Paints
9203 Highway 23Belle Chasse, LA 70037
Prepared bySean Brossia
Southwest Research Institute â6220 Culebra Road
San Antonio, TX 78228
Geri BeckerABC Consulting
19910 Encino GroveSan Antonio, TX 78259
August 2002
S O U T H W E S T R E S E A R C H I N S T I T U T E TMSAN ANTONIO HOUSTON
DETROIT WASHINGTON, DC
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The average carbon chain length for the virgin wax coating and coating samples that had been inoculated with bacteria from the MIC kits and incubated for over 60 days were determined using ASTM D2887. The average boiling point for each sample was then compared to a standard calibration curve that establishes the relationship between boiling point and hydrocarbon chain length. The results clearly showed no appreciable difference between the virgin and inoculated samples. If the microbes were able to use the wax paint as a nutrient source, the average boiling point, and thus the chain length, would decrease. As there is essentially no difference in the measured boiling points for the samples, it can be concluded that the microbes did not use the wax paint as a nutrient source.
Based on the results from this research, the following conclusions can be made:1. The virgin wax paint does not contain any viable microorganisms. Thus, any organisms collected in the void space of FMT 3003 are contaminants that were introduced during paint application or barge operations. The most likely source is from barge operations as discussed below.2. All the organisms recovered from the void space (pseudomonas/aeromonas, vibrio, clostridium, Fusarium oxysporum) are environmental in origin and are ubiquitous. In addition, the fungus (Fusarium oxysporum) is predominantly found in soils and muds. Thus, since these organisms are common to the environment, were not contained in the virgin paint, and in one case is predominantly found in soil, the most likely cause of the contamination is barge operations and the use of the void space as a ballast tank.3. Based on analytical organic chemistry analyses, it is evident that the organisms present cannot (or at least do not) readily metabolize the wax paint as a nutrient source. Thus, even if MIC is playing a causative role in the corrosion observed in FMT 3003, the wax coating is not aiding in this process.
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To minimize and prevent future corrosion on double-hulled barges, the following recommendations are made:Discontinue use of the void spaces as a ballast tankEnsure adequate surface preparation prior to application of wax coating to ensure good adhesion and minimize the risk of trapping moisture and other corrosive agents that may lead to corrosion underneath the paintIf void spaces are continued to be used as ballast spaces that will be exposed to fresh and/or salt waters, incorporation of corrosion inhibitors and biocides should be considered Inspections of void spaces for coating appearance and structural integrity should be conducted regularly
ReferencesASTM International. ASTM D2887-01a, Standard Test Method for Boiling Range Distribution ofPetroleum Fractions by Gas Chromatography (2002). G.S. de Hoog, J. Guarro, J. Gene, and M. J. Figueras. Atlas of Clinical Fungi, 2nd ed, vol. 1. Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands (2000). N.J.E. Dowling, J. Guezennec, and D.C. White, Microbial Problems in the Offshore Oil Industry,p. 27-38, E.C. Hill, J.L. Shennan, and R.J. Watkinson Eds., Wiley: Chichester, England (1987)C.C. Gaylarde and H.A. Videla, International Biodeterioration, 23, p. 91-104 (1987). C.C. Gaylarde and J.M. Johnston, International Biodeterioration Bulletin, 18, p. 111-116 (1982).C.H. Hare, Journal of Protective Coatings and Linings, p. 51-65, September (2000).G. Hernandez-Duque, A. Pederson, D. Thierry, M. Hermansson, and V. Kucera, in MicrobiallyInfluenced Corrosion and Biodeterioration, p. 2.41-2.51, N.J. Dowling, M.W. Mittelman, and J.C.Danko Eds., NACE International: Houston, Texas (1990). B. Little and R. Ray, in A Practical Manual on Microbially Influenced Corrosion, Volume 2, p. 2.1-2.6, J.G. Stoecker Ed. NACE International: Houston, Texas (2001). J.I. Pitt, A. D. Hocking, K. Bhudhasamai, B. F. Miscamble, K. A. Wheeler, and P. Tanboon-Ek. International Journal of Food Microbiology. 23, p. 35-43 (1994). J.S. Smart, Journal of Protective Coatings and Linings, p. 56-64, February (1997). R.W. Staehle and B.J. Little, in Proceedings of the Corrosion/2002 Research Topical Symposium on Microbially Influenced Corrosion, p. 33-96, B. Little Ed., NACE International: Houston, Texas (2002). 35 of 36
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