Stripping galvanizing from pipe
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Q. I need to remove the galvanizing from some pipe I plan to use in a home Propane forge for safety reasons. I know I can remove it with acid but would like to use an eco friendly substance if possible.
If acid is the best method, is the acid worthless for anything else?
Can I dispose of it properly considering the galvanized material content?
A. I can't comment on how safe or unsafe it will be to de-galvanize a piece of pipe to be used in a propane system.
But as for how to remove zinc from steel, immersion in dilute hydrochloric acid (also called Muriatic Acid [linked by editor to product info at Amazon] ) is very widely practiced, fast, and relatively simple. I don't see anything eco-unfriendly about hydrochloric acid compared to the alternatives -- do you?
Acid is consumed as it does it's work, becoming zinc chloride. I suppose, in theory, it could be converted for further use; but in this volume, it's probably impractical. You could neutralize the acid with sodium bicarbonate. For an individual, not engaged in business, I'm not aware of discharge prohibitions except at a local level.
But really, the best way to strip the pipe is to take it to a plating job shop. That's what they're there for. If you find the cost high, remember that they are paying for proper and legal recycling or neutralization and immobilization.
Ted Mooney, P.E.
Pine Beach, New Jersey
October 11, 2016
A. If you concentrate it a bit you can re-use the zinc chloride solution as pre-fluxing for soldering work. It works great to clean the oxides off off copper and is sold on shelves as soldering flux.Adrian Leighton
- Auckland, New Zealand
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