ElectroChemical Cleaning

Cleaning

Electrochemical Cleaning (ECC)SM is a very effective process using the same physics, equipment, and chemicals we use in our proprietary spot electropolishing technique. ECC was discovered when a customer had a product residue issue that looked like classic rouge yet when industry accepted de-rouging chemical applications were tried they proved ineffective. In an experiment we used the spot electropolish procedure whereby electrolyte was applied to the stained surface and the DC current was activated and the hand tool was applied to and moved over the surface the stain was removed immediately. Much quicker than the standard electropolish process we are now able to completely clean large vessels in hours instead of days, offering considerable savings to clients. By following the practices in ASTM-B912, we are also able to provide a cleaned and passivated tank prepared for immediate use.

Applications:

De-rouging: ECC has been found to be very effective for removing rouge for both electropolished and non-electropolished surfaces. An added benefit observed on items de-rouged using ECC is the rouge is very slow to return. Though conventional de-rouging and passivation methods would yield a clean product contact surface the rouge would begin to reform in a matter of hours. Studies have shown equipment de-rouged using ECC has shown rouge did not return for months and in some cases years.

Grey Residue: On equipment with a sanded or mechanically polished stainless steel surface only, it is common to find a grey residue present when the surface is wiped with an alcohol soaked cloth. In many instances the entire surface of a vessel will be hand wiped for hours using industry clean wipes until the grey residue has appeared to have been removed. The vessel may then be passivated or cleaned in place and allowed to dry only to have the grey residue return at visibly the same concentration as observed before the cleaning operation.

Our studies have shown this grey residue is made up of stainless steel powder created by the sanding process and is trapped in the folds of material created during grinding and is also electrostatically adhered to the mechanically polished surface. No amount of wiping or chemical cleaning has proven to completely remove this residue. Quality Control personnel find this condition unacceptable and express concern if the grey residue can be wiped off, it stands to reason it can come loose during product processing and become an undesirable additive.

ECC can completely eliminate grey residue in one application by electrolytic action as metal is removed ion by ion with the very outermost surface and any subsequent residue being removed.

Weld Scale and Discoloration: Prior to successful use as a de-rouging or surface contaminant removal process, ECC was developed specifically for removing weld discoloration directly on a weld or in the heat affected zones adjacent to the weld.

The process utilizes a mild acid electrolyte solution and DC current that when applied to a weld or heat affected zone (HAZ) very rapidly removes discoloration. On large construction projects utilizing austenitic, super-austenitic or nickel alloys, weld discoloration has historically been removed by mechanical polishing, blasting or a harsh chemical application, all of which alter the appearance when compared to untreated surrounding surfaces. The process has also been shown to improve corrosion resistance in these areas comparable to that of the surrounding base metal.