# Can you weld/cut on a compressor air tank



## OntarioMan (Feb 11, 2007)

I have a 30 gallon air compressor here, and everything except the tank is good. I'd like to remove the motor/pump base from the tank, which is welded on.

Someone mentioned to me that compressor tanks can contain alot of oil film on the inside, which may vapourize with heat, and that cutting into them or welding onto them is not a good idea. Although this sounds very logical to me, its something I've never heard before... but then again, I'm not a welder.

Does anyone have any experience with welding/cutting air tanks? Thanks,


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## Forty Acres (May 14, 2007)

I have a roll-around air compressor that had a pin-hole leak in one of the welded seams. I welded it with no problems. I used a stick welder.


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## greif (May 31, 2009)

if you are worried fill the tank with water then cut it off


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## agmantoo (May 23, 2003)

Grind the welds off where the base is attached to the tank


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## Ray (Dec 5, 2002)

like mentioned, you can fill the tank with water while welding and then drain the water. I've welded on quite a few diesel fuel tanks that had holes but you must take precautions, like make sure the tank is full of diesel fuel at least over the level your welding on, and have some fire fighting equipment at hand and someone else to watch while you weld to see what going on that you can not see, for safety, but I think anyone doing this should have experienced people doing this very dangerous operation. Its pretty safe if done correctly, but thats the key correctly, with more than one person for safety. We did it fairly often and were used to it and were more than safe, your life depends on it, *don't weld on gas tanks, unless filled with water!!* best wishes, ray


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## Wis Bang 2 (Jan 12, 2010)

Air compressor tanks are usually ASME pressure vessels & repairs require ASME U or R certification IF the tank is being repaired for continued useage as a pressure vessel. That's why people are cautioned against welding them.

I'd use a grinding wheel instead of a cutting torch if possible though careful torching should remove the mount without overheating the tank...the tank should make a good 'heat sink'...


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## ace admirer (Oct 5, 2005)

if you are planning to use it as a pressure vessel do NOT weld on it unless you are certified to weld on pressure vessels....its just not worth killing you or your family when the tank explodes and takes half your shop with it. grind the metal tabs do NOT undercut.


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## SamEwing (May 11, 2010)

Do not weld on the tank itself. Compressed air is more deadly than many can imagine. Cut with a cutting wheel the mounting plates as far from the weld as feasible.

Water and petroleum fumes do not mix.
When welding on gas or diesel tanks, filling with water will only compress the fumes into a smaller area causing a more volatile explosion, as when the piston comes towards top dead center in an engine. Experience teaches this.

Clean a fuel tank with a strong solution of a soap such as Dawn.
Rinse well and drain. Place an air nozzle into an opening of the tank and let a stream of air flow through the tank and exit out of another opening while welding is being performed.
This will keep any fumes from building up and will leave a nice weld joint when completed.


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## agmantoo (May 23, 2003)

The safe method is to place dry ice in the tank or some other inert gas while the vented tank is exposed to a spark or flame. Some folks use the exhaust of a vehicle but there is some danger if the engine is not burning clean.


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## ace admirer (Oct 5, 2005)

yeah, we also used argon to flush any enclosed tank of o2 and continue to flush as welding was done....still it makes the hairs on the neck stand up....


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## CIW (Oct 2, 2007)

When we remove a fuel UST. The first thing that we do is put in so many lbs. of dry ice per thousands gal. in size. Dig it up. Pick up one end, sending any liquid to the end where we have a pump stinger in the tank. Remove any remaining liquid. Put in another dose of dry ice. Tear a big hole in the top with a track hoe. Check the particulate ratio. Then cut the tank up with a torch.
After doing a few you can see when the fumes disipate as the Co2 pushes them out of the outlet pipes.
I go through the same process short of tearing a hole in the tank. If I'm welding any kind of steel container that has held petroleum.
If you are going to be welding a tank that will be holding pressure. Weld the hole shut and buff it smooth. Then using a round patch bevel the edge. Weld completely around it. Grind out the weld. Next, starting on the opposite side of the patch weld around it again.
That will be the strongest part of your tank.


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## Bandit (Oct 5, 2008)

It is Illegal to weld on an air tank in Mass. to repair it .
I have replaced a couple that were caught by a boiler ( insurance ) inspector .
Bob


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## agmantoo (May 23, 2003)

It is unlikely that I will be welding a tank in an attempt to salvage the tank for reuse as a pressure vessel. If I did, I would pressure test the tank after the repair.


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## Bandit (Oct 5, 2008)

Not to drift too far off from welding on a air tank . But I have been in the air compressor service field since 1979 and have seen several tanks that have exploded ,plus PVC lines.
Here are a couple of pic's from the internet
http://www.dli.mn.gov/ccld/BoilerIncidentsAir1.asp
http://www.dli.mn.gov/ccld/BoilerIncidentsAir2.asp
http://www.dli.mn.gov/ccld/BoilerIncidentsAir3.asp
http://www.cdc.gov/niosh/FACE/stateface/ca/05ca010.html
Bob


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## agmantoo (May 23, 2003)

Bandit,

Did you look closely at the tank that blew in this link? http://www.cdc.gov/niosh/FACE/stateface/ca/05ca010.html

I repair wells from time to time. That tank with its galvanized finish and bung locations certainly appears to be a water storage tank to me. Your thoughts?


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## Bandit (Oct 5, 2008)

Hi Agmanto
If you look closely at the 3rd. picture down you can see the industrial base of a standard 80 gal. vertical air storage tank . Those bungs are located ok for a air tank .
I think they were using what ever oil they had on hand. 
( I recently got called by a powder coating shop for water and oil in there air lines , coming from there 15 Hp. Roll-Air compressor, I asked the maint. man what he used for oil , He replied what ever the owner can borrow from the neighboring body shops and garages .
A " correctly installed " air system and an oil change or two solved the problem . )
http://www.nationalpneumatic.com/img/pdf/Anglais/MANCHESTER/MAN_Catalog-(Page-04).pdf


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## Windy in Kansas (Jun 16, 2002)

This thread keeps bugging me.

The title is can you weld/cut on a compressor air tank.

The answer is yes of course you can.

HOWEVER I think that you probably meant to ask if you SHOULD weld/cut on a compressor air tank. There is a vast difference.

Kind of like---can I cut my finger off? Should I cut my finger off?


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## ace admirer (Oct 5, 2005)

i think this is a problem that all craftsmen (chaftspeople) have....a craftsman makes their profession look so easy that the general public thinks (gee, anyone can do that) or (What? $40.00 to drive out here to look at a problem and $40/hour to do the job!!!!)....


reminds me of a joke....the doctor has a stopped up drain in the waiting room restroom. so he called a plumber....the plumber arrives and snakes out the drain....ten minute job.....he hands the doctor a bill for $120.....the doctor says @#&%#!,,,,i'm a doctor and i don't get that much pay per hour!!!...the plumber looks the doctor in the eye and says " yeah, i didn't get paid that much either, when i was a doctor"


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## Bandit (Oct 5, 2008)

I have never charged $ 40 an hour , I am a little over that depending on the size compressor , the Screw compressors , and the Joy recip's that I specialize in that are over 100 Hp. with 13 1/2 in. pistons and put out around 1350 cfm., I only charge $ 75 an hour for them , as opposed to the $ 100 + some of the other shops in My area charge .
But My advice and help is all ways free to anyone here , just ask .
Bob


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