air compressor repair

[retiredmgn]

My 25 year old, 30 gallon air compressor developed a rust hole. I ground down to clean metal and used a brazing rod with my torch and produced a what appeared to be proper repair. Not.
Air is seeping out of the repair. Three attempts have produced the same result. I removed all obstructions from the tank so air pressure would not be blowing out my brazing. I have only one remaining option. Grind off my brazing and try my stick welder. Just don't get why the brazing isn't sufficient to plug the hole.

 

[Shield Arc]

Junk that tank before it kills you!!!!!!!!!!!!!!!!!!!!

 

[sjames]

if its that thin in one spot, it cant be great in quite a few other spots as well. i don't know how anyone could feel comfortable with that sitting within a 100 yards of them.

cut it open and scrap it.

fwiw, i would imagine its the oil on the inside of the tank that's contaminating your braze, you would have to patch to get a good seal, trying to fill the hole would not work very well.

 

[Bird]

I agree with the others. No way I'd try to repair a hole in the tank, since that just can't be the only thin spot. I'd either want to replace the tank, or the entire compressor.

 

[ray66v]

I was in a similar situation 2 years ago.

A small hole had developed in the end cap, next to where it was welded to the tank. I was puzzled, because I have always had an automatic drain on it. When I stood it up on end to look at it, I realized, a bulge in the way they formed the end, had caused it to be slightly lower than the rest of the tank, trapping water there.

My compressor is a small, 30 gallon horizontal heavy commercial version, rather than the thin walled, throw away versions, they generally sell homeowners.

I used a pointed pick hammer to determine if the adjacent area was thin from rust, and also checked the rest of the tank, and found it all sound. The hammer only damaged, and penetrated the tank in a very small area, about 3/16", where the hole was.

A friend who is a pressure pipe welder, offered to repair it, but I made the decision to weld it myself. Took about 15 seconds. The compressor has been fine ever since.

My compressor has it's own room, and I have no children, or family that could use it, or can be inadvertently injured by it. All factors I would also consider before welding it.

If, and when it develops a new leak, I will replace it.

 

[retiredmgn]

OK. You guys have given me pause. Thanks.
Please enlighten me why the danger here. I removed the valve that allows water to drain - better late than never - opened the air outlet. These actions would prevent pressure building up in the tank while brazing. What could blow up here?
It seems simple enough, fix the hole, put the plugs back in, pump it up to see if it holds...
2 HP, twin cylinder Sears horizontal. Seems this thing should outlast me.

The 'oil contamination' comment seems most likely here. The brazing went well and while I'm fairly new to welding/brazing I've been soldering all my adult life. Rules are the same - clean, clean, clean.

 

[Bird]

It's not a question of it blowing up while you're welding or brazing. It's a matter of whether it will spring other leaks in the future and the possibility (not a certainty) that it might blow pieces some distance with considerable force. In some cases, when a compressed air container (tire for example) blows, the force of the air coming out on one side, propels the container the opposite direction. In other words, if that compressor has a blowout on the side next to the wall, the whole thing may fly across the room, and you would not want to be in the line of fire.

 

[Shield Arc]

My 25 year old, 30 gallon air compressor developed a rust hole.

The very first line of your post lead me to my decision.

With a rusted out tank you can chase pin holes until the cows come home. Plus with it rusted the integrity of the tank has been compromised.

 

[vwnotrunning]

The danger is not to you doing the repairs. Our concern is for you grandchildren sitting beside it airing up a bicycle tire when it has a large rupture and causes injury, blindness or death to the innocent.

 

[JDdude]

I have 2 commercial air compressor in the shop and one of them developed a leak about a year ago..I just put a screw in it and no problem since..I have another tank to mount the pump on, just have not done it.

 

[retiredmgn]

Well OK. I must admit you guys bring up valid points. I shall forego attempts to save this relic. I'm such a stuborn SOB I hate to give up on something I can repair and keep going. 100 psi could be a bit of a nasty surprise if something broke in an unexpected fashion.
****, I'm still running my grandfather's drillpress. He burnt out the motor probably before I was born, He bolted a washing machine motor on to keep it going. Works. Works fine. Looks like ****.
What are ya gonna do?

 

[wirenut]

It's not a question of it blowing up while you're welding or brazing. It's a matter of whether it will spring other leaks in the future and the possibility (not a certainty) that it might blow pieces some distance with considerable force. In some cases, when a compressed air container (tire for example) blows, the force of the air coming out on one side, propels the container the opposite direction. In other words, if that compressor has a blowout on the side next to the wall, the whole thing may fly across the room, and you would not want to be in the line of fire.

This statement is completely wrong; it is about blowing it up. Any oil bath compressor has traces of oil in the tank. Ever hear of the fire triangle? You have air, oil then you add heat=explosion. The only reason it did not explode, is good luck. Working on compressed air lines and tanks are one of the most dangerous things in a plant. If you must weld on it wash it out or fill it up with water.

 

[Bird]

This statement is completely wrong; it is about blowing it up. Any oil bath compressor has traces of oil in the tank. Ever hear of the fire triangle? You have air, oil then you add heat=explosion. The only reason it did not explode, is good luck. Working on compressed air lines and tanks are one of the most dangerous things in a plant. If you must weld on it wash it out or fill it up with water.

Oops, must have been one of those senior moments. Of course you're right. I obviously wasn't thinking too well. Glad you caught my error.

 

[whistlepig]

The certification of a pressure vessel welder is a pretty long, expensive, and rigorous process. Not all welders can certify for pressure vessel welding. It is set up this way to prevent explosions that can hurt people. And this is for welding new steel only. The risk isn't worth it to repair the tank.

 

[Scooby074]

..I just put a screw in it and no problem since..

What, out of JB Weld?:thumbsup:


Seriously though, welding on pressure vessels is serious business. Many dont understand the risks of just how bad it can be if it lets go. The tank's compromised. The rest of the tank is questionable. Replacement tanks are cheap and if the head is ok its worth a replacement.

 

[CrashandBurn]

I agree with everyone who says replace the tank.....
There's a reason all new portable tanks now have a "take out of service" date.

 

[JDdude]

yeiks..if that screw ever lets go, it would be like a bullet.

I guess it might..I have had hoses blow and they do not do much. I have had pop off valves go off and they do not do much..with the compressors where they are located..I am not to worried about it..I run 160 PSI on both units..I just do not see it to be as much of a danger as some think,,It is really low pressure at 160lbs compared to a oxygen tank for the torch..

 

[Gale Hawkins]

Some it seems have never had to "make do".

 

[JDdude]

At the Firehouse we refill our own oxygen bottles with our own tanks..It is a 3 tank system..One tank is 500lbs, next is 1000lbs then the third is 1500lbs..My air compressor is just 160lbs..I think people confuse the different kind of air tanks.