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Air tanks



poodle
03-25-2012, 11:25 AM
I have welded on air compressor tanks many times and never thought anything about it. I was welding on one at work one day and one of the hands had a fit about it. Do any of you have a problem welding on a air tank? I only weld on commercial built tanks that I know that is all they have ever been used for. I have one out in my storage building sporting a quincy comp. that they gave me at work that I have flat give up on. I have patched it about 6 or 8 times. Just welding the holes up not applying a metal patch over it.

Gadget
03-25-2012, 11:33 AM
You're basically making the tank a bomb. The heat from welding can affect the strength of the surrounding metal as well as the weld itself. Personally, I wouldn't do it. I did weld my pressurized oil tank but only use 10PSI on that to force the oil to the burner. That's a regulated 10PSI too.

matteh99
03-26-2012, 06:33 AM
The number of pounds does get pretty scary when you take a tank holding 120 psi and multiply it by the number of square inches of the tank.

Lots of air tanks have some sort of weld on them from the factory so if you can weld in a similar fashion to what the factory did logic says it should be ok if you do it right. If you do something dumb like spray the welds with a hose to cool them quicker after welding you are asking for trouble.

I would be a bit more concerned about why the tanks are leaking in the first place. If you are wearing holes in them they aren't being stored or transported correctly. If they rusted you have no idea how thick the rest of the tank is. If you are getting cracks something is very wrong with the tank.

If you were welding a bracket or handle on a new tank I would be less concerned than the holes.

To give you and idea of how powerful compressed air can be my friends and I made potato guns than ran on compressed air. Running at 100psi we were able to shoot a potato through a 3/4 inch piece of plywood. We were basically making a 2 inch hole in the side of a portable air tank. So substitute potato for piece of the side of the tank and 3/4 plywood for your body...

I am by no means an expert on welding on pressure vessels.

KHK
03-26-2012, 09:10 AM
I don't think I would weld a air tamk due to the liability. If something goes wrong it is your problem.

WookieWelding
03-30-2012, 04:27 PM
unless you have means to hydrotest the vessel to manufacturer specs after repair dont touch it.That would also include UTing for wall thickness and other testing plus you would need the WPS for the vessel . I weld on pressure vessels every day but i am also certified to do so and follow proper procedures