Metal finishing Q&As since 1989

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Bath Life and Control of Alkaline Permanganate Solution

2002

We use an alkaline permanganate solution to descale Inconel alloys. The solution consists of 2 - 2.5 lbs of sodium hydroxide and 1 to 1.25 lbs of potassium permanganate [on eBay or Amazon] per gallon of water; the solution operates at 200 °F minimum. Our specification tells us to discard the solution after 30 days (extent of usage is not considered). Assuming that we add water to account for evaporation, does anyone know if the solution will diminish in effectives if the bath life was extended to longer than 30 days? What would be a reasonable bath life? Does anyone know what tests can be performed to control the solution chemistry?

Thank you in advance for your response.

Blair Smith
aerospace - Windsor Locks, Connecticut

I would try to beg a copy of that analysis from Pratt and Whitney. They are really close to your plant. Also, you might try the analysis section of the Metal Finishing Guide book. If you do not take Metal Finishing, you should, just for the guide book.

James Watts
- Navarre, Florida
2002