Can I weld to a compressor tank

[Wheatland KB]

Welding to a pressure vessel doesn't require stress relieve or whatever else was said. Unless it is a certain type of metal and a certain thickness,this tank would be neither one.

Granted, my experience is on aircraft gas turbine pressure vessels.Thin wall, stainless alloy etc... Different animal.

The weld zone still may be supsceptible to fatigue cracking and subsequent failure.
I wouldnt do it. I've seen too many component failures on parts that were manufactured or repaired to proper standards.

My 2 cents.

KB

 

[greenmule]

Ken,After reading your stuff,[other than just where my handle is],bet your talking about an air test in a water tank,water tank being for safety ?,well,good idea,but think asme,[would have to study it a little,very little],reguires you to do a hydro test if at all possible, which this would be very possible[when done in the factory]1 1/2 times,[being both proof and leak test.].
You might not get the proof test,but you could certainly pressure it up with compressor,10-20 psi or less with soap bubbles will tell you if you got a leak,than pressure it up as much as compressor will,around a corner or something and leave it there for a while.

But if he don't burn through it,and can weld,he ain't going to be hurting that plain ole carbon steel,p1 type,so it won't blow up to begin with.

 

[srjones]

IMO, I'd say there's a difference between welding 'on' a tank than welding a tank together.

But to remove all doubts and fears, just sand off the paint on both surfaces and use a 2 part epoxy to "JB Weld" it together.

 

[greenmule]

Well just for the record[since were typeing about it],I don't plan on welding on my cheapo thin air compressor tank,BUT,if for some strange reason I decided to,pretty sure I could and could do it so's it would be just as safe as it was.But most beginners couldn't,and didn't recommend it for various reasons,etc.

But,if your going to answer the guys question,which was should he,you gotta pretty much say that,not that you'd have to stress relieve it,[wrong],not that you'd hurt the metal,[wrong],not that you'd have hydro/air test it in a 200 gal water tank,[or whatever that was],wrong again, That you have to be certified welder,wrong;just tell him the facts,you don't go welding on a thin cheap air compressor tank,unless there is a better reason than attaching his hose reel to it,[he said he wasn't much of a welder],just not a good idea.

Could you,and do it safely,sure you could.

 

[kenstrac]

Ken,After reading your stuff,[other than just where my handle is],bet your talking about an air test in a water tank,water tank being for safety ?,well,good idea,but think asme,[would have to study it a little,very little],reguires you to do a hydro test if at all possible, which this would be very possible[when done in the factory]1 1/2 times,[being both proof and leak test.].
You might not get the proof test,but you could certainly pressure it up with compressor,10-20 psi or less with soap bubbles will tell you if you got a leak,than pressure it up as much as compressor will,around a corner or something and leave it there for a while.

But if he don't burn through it,and can weld,he ain't going to be hurting that plain ole carbon steel,p1 type,so it won't blow up to begin with.

Why take cover around corner?:confused.

 

[greenmule]

Im just a extra carefull kinda guy

 

[Egon]

You need a water tank to put the tank your testing in .

Maybe explain this a little further! You may have a lot of people a little confused.

 

[mbohuntr]

My 2 cents... Been a welder for some time, saw a fella's head after a pipe he was welding on burst. not pretty... he's lucky to survive. He's not photogenic anymore... I've seen a tank burst and shredded. I've also hydro tested a few things. There's a reason compressed air cylinders are beefy, water will not readily compress so when a weld fails, there is no rapid expansion. I would never weld on a pressure tank unless It was hydro-tested and warranted to be safe. Just not worth the risk...

 

[tommu56]

Egon
You place the tank to be tested in a tank of water
The outer tank is used to check the expansion of the test vessel at a pressure.
there are limits on how much it can expand.


here is a link to simple testing Hydrostatic test - Wikipedia, the free encyclopedia

All this said some air tanks are not certified some states only require it for commercial and industrial not for personal use.

tom

 

[Egon]

Now what would the pressure classification be of a tank that had to be tested in that fashion?

For the type of tank in question do you think it would be able to be tested to around 3360 PSI ???

Actually do you think the compressor would be able to produce that type of pressure?? Heck, how would the compressor be tested?

 

[Gittyup]

Wow! Amazing how this little question has started quite a conversation. Didn't expect. I can weld good enough that my welds are strong, if not always pretty, and I know how not to blow a hole in thin metal. But, I'm not going to chance it here.

I came up with a way to attach some unistrut between the axle shaft and the top handle. I'll mount my reel to that, along with a filter and lubricator. It won't be a pretty thing, but it'll function quite well. Just gotta be careful when welding the heavy unistrut to the thin metal tubing that forms the handle. I might also add a small u-bolt too. At the axle shaft, I'll simple cut a slot in the unistrut for the axle shaft. Let it rest on the shaft and tack weld it.

I want the complete rig to be mobile so I can take it to my barn or use it in my garage. That is why I don't want to mount the reel to the wall.

 

[greenmule]

Tom,makes sense how that works,just never heard of a hydro test done in that fashon[well,it wouldn't be a hydro test,it would be pnematic test really].
The way power plant boilers,pipelines,and anything else I been involved in are tested,is you put a vent in high spot,pump water in low spot,when water comes out high spot,you close valve and keep pumping generally to 1 1/2 times design pressure,hold for a cerain period,check calibrated gage or dead weights,etc,etc,
May be at nassa they do a test like that,don't know.
Bet somebody was right most of these cheapo's ain't even to asme 8,so probably an air test at 50 lbs of some sort.probably not even that.

 

[mbohuntr]

Good idea gittyup, there's not much room for error on a thin 150 psi tank. No, it's not a 3000 psi cylinder, but imagine it letting loose in your car, or when your or a neighbor kid has their hands on it. I've been certified quite a few times, and i'd never do it. Way too much liability.

 

[greenmule]

gittyup,no,thanks for that question,led to alot of good stuff. But yeah,I wouldn't weld on the compressor air tank either,

So whats your next one,can't wait!

 

[greenmule]

Tom,do you put air in the tank thats in the tank,or do you put water in the tank?

Cause if you put water,than it would be a hydro,under the hydro.

 

[Gittyup]

OK. A follow-up question: My welder has a chart for setting the current and feed speed based on metal thickness and composition. But what setting do you use when the parts to be welded are of drastically different thicknesses?

Another question: How or can you weld aluminum to steel?

Obviously, I'm new at this welding thing.

 

[greenmule]

You just do the best you can there gittyup,turn it up.

 

[tommu56]

Tom,do you put air in the tank thats in the tank,or do you put water in the tank?

Cause if you put water,than it would be a hydro,under the hydro.

Water goes in side Don't ask me why I use to have my scuba cylinders done and a friend did them while I was there.

I don't think most air compressor tanks are done under water.

We had a deairartor (part on a steam system) at work modified to get to the nozzles that were malfunctioning and that modification was engineered by and engineer and welded by a certified welder and a new asme plate was welded on to amend the change and we had to pump it up to 150% of working pressure which was only 30 psi tested to a whopping 45 psi.

But at 10' diameter that would be 508,938 lbs of pressure on that 10ft area.
I wouldn't want to be around if it came apart.

As a comparison a scuba cylinder at 6" diameter would have about 84,823 lbs at 3000 psi

tom

 

[greenmule]

Well,thick to thin/thin to thick,if you got her set to hot,you'll burn up the thin,so its just practice on something like that[depends on how thick to thin],but you put your puddle on the thick mostly,and let it come onto the thin,and depending on how thin,you gotta go fast,you'll just have to experiment,

Aluminum to steel,can't do it far as I know,you would need one or two middle metals in there somewheres. Braze/solder,would be the thing to do there I think[or screws].

Come on there men,tell him how to weld alumn. to steel.

 

[greenmule]

Tom,scuba tank tests are done under water with pressureized water!,I knew this was something different.
yeah,psi and gas stuff= big bad boom,thats the reason for hydro,it might kill you if your standing next to it,but it won't blow the whole damned building up.