Sand blasting the outside of old steel 72 tank good idea / bad idea?

[minimalistdiver]

I have a couple old 1960's steel tanks that I just got back from Hydro and visual. I had to have one of them tumbled too.

They look kind of ugly on the outside and I would like to primer and paint them.

Paint removal:
I bought some paint remover. But I do have a nice sand blasting cabinet in my garage that would fit a tank perfectly. What do you think? Should I do it? I wouldn't remove any surface metal on the outside. Maybe just at a microscopic level. Is this a bad idea? I don't want to weaken the metal so that I make a bomb. But I have removed paint with paint remover before and I can tell you from past experience, that I cannot refrain from taking a putty knife to the surface and scraping away the tough to remove paint. Which in my opinon would score scratches in the metal surface.

What do you think?

New Paint:
Also, what kind of primer and paint should I use? My first impulse was to call the local professional auto paint store and get some epoxy primer. But their smallest size with the catalyst is 30 or 40 bucks. All I have to do is two tanks and that raises what I have in these old things another $20 a piece. I bought a quart of Dupli Color primer Surfacer from Schucks and thought I would use that, and then could finish them off with some rattle can paint. My main thing is, I don't want the tanks to rust on the outside and would like them to be durable. But I am over budget on these old tanks already. For what I have in them I probably could have bought two nice used aluminums from my local dive shop. A lot of the expense was two new XS Scuba taper thread din valves.

 

[mictrik]

I am surprised no one has answered as yet, I am sure many have done this type of renovation. I was told that Rust-oleum System 9100 (industrial line) was a great solution but my understanding is that it only comes in gallon sizes. I have never used it but i also have some steel 72's that need to be protected.

 

[Jim Lapenta]

Can you use soda with your blast cabinet? Much easier on metal. And rather than piant them get some CRC galvanizing paint. They may be galvanized underneath any way. Old steels look cool galvanized and the CRC stuff once cured is damn good stuff.

 

[DA Aquamaster]

Agreed. You want to take care not to remove a galvanized finish if it's present. The CRC cold galvanizing paint is about the most durable available ad it looks pretty good - but it is not cheap.

I've tried a variety of two part epoxy paints and polyurethane enamels over the years and have yet to find one that hold up well.

Consequently, if I really want a colored tanks and/or have one where the galvanizing is thin and no longer effective, I'll paint it, but only then. However I have tended to back off on high dollar automotive and aircraft paints and instead just use a regular rattle can paint with zinc in it (Rustoleum, etc). I have found that 2-3 coats applied a week or two apart hold up pretty well, but I still plan on scuff sanding and hitting them with another coat every year or two.

 

[muddiver]

If you sand blast you will remove the galvanizing and the cylinders will began to rust. I don't recommend paint unless you plan to spot blat ay blisters that appear and touch up every scratch after every dive. Paint has a tendency to leak thgough at pin holes and then you will get crevice corrosion that will pit the tank under the paint. I vote for re-galvanizing the cylinders. Spray on cold galvanizing will last longer than paint but not as long as a good hot-dip.

 

[Gilldiver]

Use a chemical stripper with methylene chloride in it, but out in the back yard as that chemical is heavy on the body. If you need to scrape the paint to get it off, use a wood scraper.

I have access to chromated aircraft primer (MIL-DTL-23377 or MIL-DTL-85582) and paint (MIL-PRF-85285) which is what the Navy uses for aircraft with good results over time. But, if you can't get one of thees systems then use the CRC materials

 

[DA Aquamaster]

Paint has a tendency to leak thgough at pin holes and then you will get crevice corrosion that will pit the tank under the paint. I vote for re-galvanizing the cylinders. Spray on cold galvanizing will last longer than paint but not as long as a good hot-dip.

That's exactly why you want to use a paint with zinc in it.

Unfortunately, the DOT does not allow hot dip galvanizing on anything other than new production tanks.

 

[spectrum]

Unless you get a rush from making old stuff new again look long and hard at this before buying premium products and investigating time, let alone signing up for perpetual maintenance. You may be able to flip them as-is and move on. Hot dipped galvanized is timeless, paint is.... well, it's paint.

Pete

 

[Max Speed]

Glass bead blasting will remove the crud and strengthen the tank by relieving any uneven surface tension and micro cracks in the metal. (This is why connecting rods, crankshafts and engine cases are bead blasted.)

Repaint with ZRC brand cold galvanizing. The ZRC brand has a higher percentage of zinc vs binder than most brands and is more durable for bridge ironwork and industrial cooling tanks. The spray can ZRC may not have as high a zinc content. We have found that the ZRC brand will last at least one year of continuous immersion in even poor quality water. The downside is that high concentrations of chlorides will act as a paint remover. I would rinse well after pool or saltwater use.

Sent from my SPH-P100 using Tapatalk 2

 

[RonFrank]

A gallon of galvanized paint will run $75-$185. A quart runs $28+. Steel is worth doing right. You may want to look into having the tanks hot dipped. I have no idea what that costs but worth looking into. Done right it can last a lifetime. However it makes no sense spending what it would cost to buy new. Rustoleum will work fine but you will be painting annually.

You can also look into Marine Grade Paint For Yachts And Boats | Boat Bottom Paint | Chesapeake Bay Coatings