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Mild Steel Plating, Chemical Resistance

2004

Hello finishing world,

I'm an artist building a common-duct watertorch from dead patent info and for personal use. The device is a sealed electrolyzer container operating at 100 psi max. It is filled with 30%(max) NaOH solution.  For this design, 304SS, EPDM, and PVC have proven effective and compatible.

My Questions are: What sort of results could I expect from building the container out of mild steel, polishing, and then plating Ni on the wetted surfaces? Is there any advantage to adding a Cr plate? The environ is O2 and H2 rich? What effect might this have on the plated mild.

Thanks for your time. People who give freely of their knowledge make the world a better place.

Aaron Gallemore
artist - Albuquerque, New Mexico, USA

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I don't know what a common-duct watertorch is, but if it contains 30% (max) NaOH you may not need any coating at all. The great majority of caustic cleaning tanks used in metal finishing shops are fabricated of plain carbon steel and uncoated. The alkalinity prevents rusting.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004

Ted, thanks for your comment. I would like to be specific in my understanding of your response. Could 30% NaOH be expected to prevent rust even if the solution were supersaturated with oxygen. This will be the case at all times, as the electrolyzer supersaturates the solution with O and H. How would a lower concentration of NaOH say 15% effect this?

Aaron Gallemore
artist - Albuquerque, NM
2004

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I can't answer that or provide much input beyond what I have. The majority of plating shops use steel tanks for caustic cleaning solutions even when they are electrified, and producing nascent oxygen and nascent hydrogen. Anything beyond that is extrapolation.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004