Anyone Ever Built an Air Tank?

[justinp61]

I'm in the process of getting everything together for a air compressor, already have a large Ingersoll Rand pump and have found a source for the motor. I can't find a decent tank near home. I do have some natural gas line pipe that is 30" od, 3/8" wall and a friend has a sheetmetal shop that can cut the ends (3/8") on his plasma cutter. Has anyone ever done this? I'm not worried about the welds, but is there anything else I need to look at?

Thanks, Justin

[KBar]

I never heard of anyone that has built their own air compressor but considering the pressure that is going to be in the tank, (30" WOW) you may want to reconsider. I did hear of the older tanks (50's style) blowing up on guys taking their leg off or worse.

[justinp61]

Make sure you dome those ends!

Can I buy domed ends?

[KEENAVV]

Buy a tank. You'll live longer!

[justinp61]

Buy a tank. You'll live longer!

You're probably right, I've been looking for a while. Shipping is outrageous on these things.

[kcstott]

Buy a tank. You'll live longer!

I second that. 30 inch end plate at 120 PSI is 84,823 total pounds of force or just over 42 tons. That's 900 pounds per linear inch of weld. No thanks I'd rather have that little tag on the side of the tank say it's been tested and certified. because if it does fail for any reason your insurance will not pay.
and that's the least of your worries

[aametalmaster]

I also would buy a tank. Without the ASME stamp on the tank you are asking for trouble someday...Bob

[KBar]

I’ll bet by the time you factor in the cost of the domes + the shipping, a replacement air compressor tank will be more appealing.

One cheap prosthetic alone is close to $10,000 let alone the pain & suffering. I among many others on this board would hate to see a fellow welder get hurt trying to save a couple dollars.

[Sberry]

I agree with most guys here, generally this is not a good idea, scares me to think of some of the stuff I did when I was a kid,, and then some.

[Broccoli1]

Buy a tank. You'll live longer!

I don't understand this line of thought as SOME ONE makes the tanks?

Why can't Iron head or any one else that is qualified to do so make their own tank?

[KEENAVV]

I don't understand this line of thought as SOME ONE makes the tanks?

Why can't Iron head or any one else that is qualified to do so make their own tank?

Check the requirements necessary for a high pres. welding cert.

[Broccoli1]

Check the requirements necessary for a high pres. welding cert.

As long as the person fabricating the Tank has the certs, what would be the problem?

[Laiky]

i think the problem is that the people who make the tanks, make hundreds and thousands of them. they have experience, empirical testing and certs. To make just one, you don't get any of that. I'd buy it so you can get the experience and quality of the above mentioned. Same reason some one who isn't an experienced welder shouldn't be doing critical work, and should pay a qualified person to do so, instead of suffering the learning curve for one job.

[enlpck]

As long as the person fabricating the Tank has the certs, what would be the problem?

It isn't just the weld job itself... It is the design process, material verification, NDE On the finished product, and about 50 other things. The risk is much greater than the (possibly nonexistant) cost saving. The risk may not show for several years.

For examlpe, a minor design issue led to some failures: http://www.cpsc.gov/cpscpub/prerel/prhtml02/02108.html

To get an idea of the energy involved,
http://www.railpictures.net/viewphoto.php?id=176187. The tanks on this locomotive arn't really that big. Well, weren't. Note the bent running board. The channel at the edge was maybe 4", maybe 6". The doors and engine compartment structure were also bent up (look at the roof... it is humped).

[kcstott]

Better yet, hydraulic cylinders, steam lines, on and on and on.

Not saying you can't. Liability is one issue. And I'm not referring to damage to your own home how about the guy next door. If you house catches fire that tank if pressurized and no safety valve will end up a couple of zip codes away. Same goes for hydraulic cylinders. Are you willing to bet your life on your welds. Training, experience, those are the qualities of the guy i want welding my steam lines, hydro cylinders, and air receivers. But then when you take into consideration cost of materials and fab time. Along with learning how and why the tanks are designed the way the are. Add in the threaded bung fittings and safety valve it starts to add up. and to me it just ain't worth it. Oh did I mention I'm a cheep SOB too. and I still wouldn't make an air tank that big even at half the cost of new.