Welding to an EMPTY air tank

Just got a 7 gallon tank for my OBA setup however it's odd because it has no feet or mount brackets of any kind. I'm not worried about my welding ability but I am worried about maybe stressing the sides of the tank when I burn in a few brackets on the side. Is this a legitimate worry or does it hold no air (har har har) I plan to keep it around 75-110 Psi

Welding a pressure vessel is a risky proposition. If nothing else, have it hydrostaticly tested when you are done.

I would look into getting air tank mounts that clamps around the circumference of the tank... Not sure of a source though, but I know they exist you see them on semi trucks from time to time, they also make large diameter u-bolts as mounts (much more common on semis) but I'd think it'd be less desirable. Both are definately worth looking into though.

I could use some of those clamps as well. I want to mount my air hose takeup reel to the side of my upright 80 gallon air compressor tank.

just prep it really well and weld with a lower heat...

110psi is very low pressure.. worse case scenario, it cracks while full.. and all you should hear is a loud hiss of the air pressure loss.. Now, 2000psi.. is a much different story!

Options:

1) Find the strap clamps to use - you can probably find them at heavy truck parts houses for the smaller tanks, or adapt something from a hardware store for a water heater for larger ones.

2) Prep, weld, post-heat-treat (normalise,) and hydro test.

Option #1 should be rather cheaper and much easier!

Thanks guys! I'm going to my local fleet pride to see what they have tomorrow. I was also thinking about gas tank straps and modify them a little bit.

Welding a pressure vessel is a big deal. The company I work for (boiler) has an "R" (repair) stamp which is big bucks to get and maintain. There is a whole process to follow to do repair or alter a pressure vessel. That being said, we are dealing with steam from 15psi to 500 psi in boilers the size of train box cars which would take out a city block if they exploded. I think you would be fine just make sure you have a pressure relief valve.

I make mounts for refrigeration tanks all the time. I'm pretty good at it, but even a novice should be able to turn out something serviceable without too much trouble. Some flat stock, a vice and a ball peen hammer is all you really need. An Oxcy acetylene torch may be helpful, it depends on the quality of your flat stock.
Start out with a bunch of little bends in the vice about an inch apart until you end up with a loop (or nearly), hammer the loop on something solid and curved, kind of working it into a tighter loop. I can do most cold, some metal develops stress cracks and needs some heat. The hammering makes heat of it's own and if you are good you don't need any additional heat.

Any place that does steam pipe or even plumbing supplies should have wall anchors and straps for pipe, should be easy to modify.

Just a quick idea, wrap the cylinder in chain, use a bolt to tighten the chain, weld your legs to the chain.

Most tanks are internaly coated to prevent rust, welding destroys the coating.

I'd look at a ring bender from Harbor freight and some flat stock before buying something for a big rig. Bet it would be about the same price and you'd still have the ring bender for other projects.

NEVER weld an air tank. Not a good idea, you would be amazed how much damage 100 lbs of pressure can do.

I'm a Medic, I've run these calls where small tanks have exploded while being filled. Nothing like having half your face blown off to ruin your day.

DON'T do it.

On that note, you can make a safe and cheap holder for your tank by using 1"ratchet straps that closely resembles the same securement we use for out O2 tanks in the ambulances.

Be careful

Think of making a bracket that cradles the tank and then use the 1" straps to hold it in the cradle.

Please DO NOT weld to a pressure vessel. Even a pressure vessel letting go at a relatively low PSI ( say even 30-40PSI) could be very dangerous. Do a quick google search on air tanks exploding, maybe search through weldingweb.com. I've done it before and nothing bad happened (knock on wood) but have since scrapped that tank and will never do it again since seeing what can happen when a pressurized tank gives up the ghost. Pick up some 1/8" flat steel, 1" or 1.5" wide, you can easily hand bend this around the tank making straps to which you can safely weld legs or whatever you want to (when the steel is not bent around the tank, don't want to heat the tank metal). Use a piece of string wrapped around the tank to get a rough measurement of how long you should cut the flat steel. Just my $.02.

X-whatever, don't weld on the tank. 100psi isn't a lot in the world of pressure vessels, but it can still kill you if the tank fails.

How big around is the tank? How about a pair of band clamps holding the tank to a home made bracket.
I can't get a clean link to the page, but McMaster-Carr lists band clamps here under hose and tube clamps up to 7" dia.
http://www.mcmaster.com/#hose-and-tube-clamps/=d04e2q

Nitros tanks and fire extinguishers are held down in race cars with band clamps. 'Should work for an air tank.