welding an air tank?

[MontanaMan]

Hey ... this probably sounds like a dumb idea, but I was thinking of welding an air tank out of 1/8" steel.

That would be much thicker than store-bought tanks, and I would even be able to treat the inside with rust-prevention compound -- like the rust-proofing they use on cars.

I think to bend the steel into a cylinder would be very difficult, so the best way to do it would be a 16 X 16 X 48" box, which would be about 53 gallons.

I know that a square box isn't as strong as a cylinder, but with 1/8" steel, it should be overkill, right?

What do you think? Criticism and suggestions are welcome!

[jfsmith]

The variables are based upon your skills and your ability to test the stenght of the tank.

But by the time you you have the steel and welding equipment together, it maybe cheap to buy a used tank.

Just my thoughts,

Jerry

[aametalmaster]

I welded up a tank 25 years ago to use in a wood boiler, i made it from sheet 1/8" plate. It was 24x24x3" thick. I pressured it up with air to test it and the sides pushed out like a big fluffy pillow, now it is 6" wide in the middle. Needless to say i didn't use it but it didn't leak either.
This is just my opinion, i would not build a tank today because of the liability if something did happen even way years down the road unless you are certified for pressure vessle work...Bob
New tanks aren't that expensive from even Graingers.
http://www.mcmaster.com/ PAGE 891 Air Tanks

[MontanaMan]

Ok ... that was a bad idea ... my apologies :-)

[monte55]

If you're thinking of making your tank to save money,........don't. But if you need a custom size then try it if your welding skills are up to par. If it is a square and you don't want it to pillow out maybe you could put a rod through
it and weld the ends or just use heavier plate. I would restrict this idea to small tanks like on a motorcycle or small project. Tank failure danger would probably be in proportion to its size. Persons using old freon tanks and such
being discouraged is because of the internal rusting and weakening of the tank from moisture from compressing moist air. The tanks are capable of holding pressure greater than most home shop air systems plus they have a pressure safety on them. What will go into the tank and at what pressure is the key issue. I would much rather be around a small tank that failed than
a large say 80 gal that burst. There is a lot of kinetic energy there. Be careful.

[ace4059]

I would much rather be around a small tank that failed than a large say 80 gal that burst. There is a lot of kinetic energy there. Be careful.

I would not want to be around ANY air tank that ruptures. Have you seen pics of then after that exploded? Plus they can throw shrapnel when they explode.
Heres some pics of one. Looks like it rusted out then went KABOOM
http://www.doli.state.mn.us/airtank.html

[MontanaMan]

yeah ... I'm definitely not going to try to weld an air tank ... that was just a bad idea all around. A few days ago, I found those same pics you linked to and didn't like the look of it at all!!

Notice that they mentioned that the drain valve was removed and the outlet was plugged up. That's obviously why it got so rusty in the first place. Me ... I did the exact opposite. On my little dual-tank nail-gun compressor, I put two ball valves on it so that I could drain them more easily. I always drain them after each use, and tilt the compressor around to make sure all the water is draining out.

About the freon tanks ... I've been thinking of ganging together a few of the disposable tanks ... they are rated at 250 psi, which is 50 psi greater than the store-bought compressor tanks. The only downside is they have no plumbing for a drain valve. So ... perhaps I can carfully weld in a drain valve there. I haven't decided yet.

Thanks for all the input ... and keep the ideas coming!! This is very helpful.

[jfsmith]

Robert,

Have you thought about seeing if your local bottle gas place has gas bottles and or vessels that don't meet pressure standards, they would make great bottle for 200psi.

I have never done this, so I am not if it will work, I just thought I throw out this idea.

Jerry

[MontanaMan]

Robert,
Have you thought about seeing if your local bottle gas place has gas bottles and or vessels that don't meet pressure standards, they would make great bottle for 200psi.

I have never done this, so I am not if it will work, I just thought I throw out this idea.

Jerry

Yeah ... I called a welding supplier and they said the largest they can get are some 4-foot by 7-inch scrap bottles for $15.00. Those are still pretty small by compressor standards, so I'm thinking that ganging the free freon tanks together might be a better option.

If I do go with the freon tanks, I'm going to spray the inside with some kind of rust preventative. I'll have to be able to get a wand in there or something. Or maybe I can use an agricultural sprayer to get inside and coat it with something. Anybody have any ideas what kind of spray would work well for that? Paint? Rubberized undercoating (not the oily kind)? Other ideas?

I think the key thing is to take proper care of whatever tanks you use.

[aametalmaster]

I would just use a good primer and some oil base paint, pour it in the valve hole, coat the inside, then turn it upside down to drain and air out. If you want to get real fancy use some POR15 gas tank sealer that stuff is tough as nails...Bob