Summary for stripping galvanizing from pipe Discussion
Stripping galvanizing from pipe is discussed as a practical metal-finishing task, but the safety of using the pipe in a propane system is not addressed by the answerer. Vance Burns asks for an eco-friendly way to remove zinc from galvanized pipe and whether the acid could be reused or disposed of properly. The reply says dilute hydrochloric acid (muriatic acid) is a widely practiced, fast, and simple way to remove zinc from steel, and notes that the acid is consumed in the process as it becomes zinc chloride. The answerer says there is nothing especially eco-unfriendly about hydrochloric acid compared with alternatives, though reuse is probably impractical at this scale. For disposal, the acid can be neutralized with sodium bicarbonate, and local rules may apply. The best practical option, according to the answerer, is to take the pipe to a plating job shop for proper stripping and legal recycling or neutralization.
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?
Thanks
VANCE BURNS
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
⇦ on
eBay or
Amazon [affil link] ) 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.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
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
1996