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October 23 - October 29, 2016

What is most effective treatment for steel contaminated with MIC before painting?


Selected Answers

From Regis Doucette of Durable Solutions on October 27, 2016:
It is understood that there are many types of MIC (Microbiologically Influenced Corrosion) in different environments. The American Petroleum Institute has identified this common issue and addressed it in Recommended Practice #652 entitled “Linings of Aboveground Petroleum Storage Tank Bottoms." The key to the successful control of this problem is to identify the potential presence of soluble sulfate by testing for that specific ion. It is the sulfate ion that serves as a nutrient for organisms that generate MIC, so its presence and identification are pivotal for mitigating and eliminating this type of corrosion. As an aside but very relevant point, testing by conductivity provides an indication of conductive species presence and NOT the presence of the sulfate ion. This referenced document offers guidance to facilitate inspection and application of protective coatings in environments affected by MIC. It echoes what other groups and current best management practices suggest—that abrasive blasting alone will not remove non-visible contaminants of soluble salts from surfaces. Further, it indicates that even high pressure washing may not reduce salt contamination to an acceptable level. What is offered is the use of commercially available and approved soluble salt removers.

From James Prevatt of SPEC-GUARD on October 26, 2016:
Once MIC holes are discovered, the related tunnels are to be opened by using grinding methods to trace and expose as much a possible the underlying tunnels. Wash the exposed pits and tunnel surfaces with a liberal application of 7-10% solution of hydrogen peroxide to thoroughly flush the effected area. Use all necessary safety precautions. Thoroughly flush the surface with fresh water, air blow dry and repeat the saturation with Hydrogen Peroxide as above for a second time. Re-wash and allow to dry thoroughly.

From David Grove of The Grove Real Estate Group on October 25, 2016:
When I was the Corrosion Control Manager for an offshore drilling contractor, we had many pre-load and ballast tanks where MIC was a problem. In these areas, the corrosion levels were very high. I required that the heavy corrosion be removed first by rough blasting with abrasives or UHP waterjetting, depending upon access and conditions. UHP was the most common method used. Once the steel was exposed, a biocide was used. After, the conditions were controlled and the surface was prepared for coatings. What was difficult was the access to the backsides of angles, but staying focused during the project ensured success. I left the company years ago, but as I understand, the tanks on the many rigs continue to show extended corrosion control.

From Ramchandra Survase of Thermax Ltd on October 24, 2016:
Use both mechanical cleaning and chemical cleaning to remove bacteria.

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Tagged categories: Asia Pacific; EMEA (Europe, Middle East and Africa); Latin America; Microbiologically Induced Corrosion (MIC); North America; Steel


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