Cleaning zinc corrosion from steel tanks

[Paladin]

I have just acquired three steel 72s (one PST and two Healthways) that had tank boots on them. I removed the boots and all three tanks have white zinc corrosion where the boots used to be. What would be the best way to remove the corrosion? Thanks.

 

[captain]

If you leave the boots off it will eventually fade away with use. You can brush the loose stuff off with a wire brush. Trying to remove it using acid can eat completely through the zinc and then you have a place for rust to form.

 

[Paladin]

Thanks, Captain. I got the tanks off Ebay. Two Healthways 72s, in current hydro (2008, 2009) with a nice, clean USD manifold w/J valve for $150. The other is a 1970 PST, out of hydro, no rust or corrosion (other than where the boot was) inside or out; $60.

 

[Texfrazer]

Thanks, Captain. I got the tanks off Ebay. Two Healthways 72s, in current hydro (2008, 2009) with a nice, clean USD manifold w/J valve for $150. The other is a 1970 PST, out of hydro, no rust or corrosion (other than where the boot was) inside or out; $60.

Ah, so you bought those. Glad it was an SB member. I thought long and hard about them, but it's hard to talk the wife into "another tank!".

 

[Double Diver]

I have just acquired three steel 72s (one PST and two Healthways) that had tank boots on them. I removed the boots and all three tanks have white zinc corrosion where the boots used to be. What would be the best way to remove the corrosion? Thanks.

You should not use a steel wire brush, it is harder than the zinc and will result in a greater possibility of rust because of the removal of zinc and the little bit that wares of the brush itself being deposited on the surface. My first choice is copper or bronze and then SS steel at least it wont deposit anything new to rust.
Oh yes, and patience.

 

[duckbill]

Just remember, if it is truly corrosion instead of just a mineral/salts deposit, then the zinc will be thinner there. Don't overdo it. Remove just the loose stuff that traps water and you'll be fine. May not look like new, but then you will become known as "Old Salt" the way a vintage diver should be.

 

[John C. Ratliff]

I'm with Duckbill on this. The zinc coating is there because zinc, when it "corrodes" is self-limiting. It forms a protective zinc oxide coat over the steel. Remove the zinc, and you remove the protection which keeps the steel from corroding, which is not self-limiting--it is accelerating.

SeaRat

 

[Paladin]

Thanks, guys. These are the first plain, galvanized tanks I've owned. Up to now, my experience has been limited to tanks that were either paint over galvanized steel or vinyl over galvanized steel, so zinc corrosion just hasn't been a problem. After reading your replies, I have decided to just leave them alone and, as the Captain said, let the corrosion take care of itself. I may, later on, put a couple of coats of a good polyurethane paint on them.

 

[captain]

Thanks, guys. These are the first plain, galvanized tanks I've owned. Up to now, my experience has been limited to tanks that were either paint over galvanized steel or vinyl over galvanized steel, so zinc corrosion just hasn't been a problem. After reading your replies, I have decided to just leave them alone and, as the Captain said, let the corrosion take care of itself. I may, later on, put a couple of coats of a good polyurethane paint on them.

Unless color is why you want to paint them, paint will offer limited extra protection.

The by far the best coating is ZRC Galvilite.

http://www.zrcworldwide.com/p_galvilite.asp

 

[dumpsterDiver]

It is amazing to me but those old 72's seemed to have better galvanization than the new expensive steel tanks like OMS etc. I have had rust issues on the big LP steels that was nothing like a galvanized, unpainted 72 steel tank. Stay away from rubber boots and the old steels should stay fine with a little care.