# Welding on air compressor tanks...



## biguglycaprice

I've read a lot about the dangers of welding air compressor tanks. Most of these warnings are about fixing pinholes/leaks, as the damage is often much more extensive than meets the eye. My question is whether or not it is safe to weld brackets to the top of a newer/leak free tank. I need to weld on a bracket to mount a different motor/compressor. 

What do you guys think? Could this potentially be life threatening??? :welding:


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## chief

Are you a GOOD WELDER???   If Not Don't Do IT,  I seen a 60 Gallon 125 psi tank take out the wall in a shop a few years back, It can Kill You are some one in you family.
And there is a lot of Vibration with the compress and motor mounted on top, so your welds could tear out and then  " BOOM " 
And then your fine Navy Day Just Went To Hel....


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## Tom Griffin

Phillip,

I wouldn't hesitate to weld a bracket or two on the outside of a tank,  but fixing leaks is a different story. As on cars, visible rust is  only the tip of the iceberg.

Tom


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## Rbeckett

I personally would choose to mount the motor and the pump on a seperate plate or enclosure and run piping back to the tank.  That way you have ease of servicing and you arent taking a chance with poor quality welds.  Pressure vessel welders have a special cert and WPS they follow to prevent explosive issues.  Unless you have that cert, do NOT weld on a tank.  The HAZ can affect the integrity and cause unpredicted failure.  Just not worth the chance.
Bob


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## Tony Wells

Given the fact that most tanks do have the bracket/mounting plate welded directly onto the tank, it obviously is possible. But consider the regulations that govern ASME Pressure Vessel Welding. Not many home shops are equipped, nor or most hobbyists trained/skilled in this field. 

Even so, it's not impossible. Just risky. If you understand the risks, and are willing to do the appropriate testing, there's little reason not to do it. But be aware that some states prohibit non-code welders from working on code required vessels. I would imagine a catastrophic failure resulting in an insurance claim would likely run into some problems if the cause were traced to a non code weld.

If there is already a mount on the tank, can you weld a new plate directly on top of it with the correct hole pattern in it? Or maybe even leave the "sides" and maybe an outer ring intact and weld on a new plate?

Even in the case of pinhole leaks, it is possible to plate weld a patch over the entire bottom of the tank, where rust usually causes these pinholes. Same rules apply though. Risk, skills, regulations, and testing. On another forum, there were several pages of yes and no opinions on this issue. Generally, most people seem to think it's better to replace the tank. On smaller compressors, it's probably not that hard to find an identical or similar enough replacement by sourcing a dead pump or motor at a surplus center or garage sale even. Larger tanks might be harder to locate, but probably could be had reasonably from a compressor service center.


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## dickr

Is it an OLD OLD tank? You know one with 1/4" walls? I got welding machines but I'm not a "Welder"
See if you can mount it mechanically. The new ones are pretttty thin and done automatically and have certs
dickr


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## biguglycaprice

The tank is basically new that will be used. I have decided against welding to the tank as the risks are more than I am willing to take.

The reason I wanted to weld to it is because it's a portable gasoline powered unit- 8hp/lots of cfm. What I've figured out is that i can bolt a much longer mounting pad to the existing pad and then run supports for the overhang to the axle. I may have to weld the supports to the axle, but that is not a pressure bearing surface so I don't see a problem with that.

Does that plan sound more reasonable?


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## Tony Wells

Yup, that's what some of us were suggesting. Go for it.


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