Welding on OLD air compressor

Date 06-07-2009 06:38 Edited 06-07-2009 12:43

I have a neighbor who has a very old air compressor TANK (maybe 50 years or so) that has a leak in it. It has a welded nut on the bottom of it used for a support stud. It is leaking around the edge of the weld bead where it is attached to the shell of the compressor. It's cracked half way around the weld bead. The compressor appears to be made of very thin steel. I'm wondering if it's safe to weld on this or should I tell him no due to safety. I don't want anyone to get hurt. The compressor is about 3 feet long and around 14" or so in diameter. I'm a welder by trade but would be doing this as a favor and not charging him or anything. Opinions appreciated.

By JMCInc

Date 06-07-2009 13:46

The inside of the tank is most likely rusted. Does the weld around the nut have any undercut? Picture in your mind's eye the tank slowly rusting from the inside out, making the tank walls ever thinner and thinner. Logically, it would crack and leak at the thinnest part.

The tool repair shop here has a tank that was never drained and consequently rusted from the inside out. One day it exploded and went through the ROOF of the house that was being built. Also I was working on a compressor with a pet cock that was broken. It still had a full charge of air on it and I stupidly didn't pull the pressure relief valve. I thought I could just screw it out enough to bleed the air off then replace it with a new one. Well it blew off in my hand and injected bits of tank particulate and rusty water into my skin. That little stunt earned me an hour and a half with a doctor digging around in my hand with miscellaneous pointy objects. You know the saying "You can't fix stupid"? Well you can, with PAIN or DEATH.

My advice... buy a new tank. Heck, buy a new compressor.

By awspartb (***)

Date 06-07-2009 16:47

Yes, that's what I thought also. It seems VERY thin and the nut was welded on the bottom by someone years ago and used as a support for a bolt to keep it level. I feel bad that I told the guy I'd do it but I can't risk somone getting hurt. Especially when you can buy a new Craftsman compressor for $119.00. I'd rather buy the guy a new one than weld this thing and have to worry about it killing him.

Thanks

By DaveBoyer (*****)

Date 06-08-2009 04:11

Generally, it is not a wise repair to make. I can't say that I wouldn't or hav'nt done it. If You ar going to mess with it be sure there is some thickness to the tank. The crack You described may have come from fatigue. Vibration may be responsible for that crack rather than from the tank rusting out.

The one I did repair was rusted and had pin holes through a few places, but was sound enough around those areas to weld to. Good idea? NO. Would I do it again? I don't know, I have another small tank that is pin holed too. Depends what the rest of the tank bottom looks like.

By FixaLinc (****)

Date 06-08-2009 04:43

I wouldn't mess with a old tank that small. Check www.surpluscenter.com or www.grainger.com for new air tanks. Besides being rusted it can have a film of oil in the metal pores as well.