Welding Tips and Tricks

Hi i got to weld some small tubing wich i dont normaly weld. I got mig .tig and stick at home. Im just a hobby guy and do welding projects for my self. Im way more comfortable with stick and mig than a tig, cause i havent had the tig long. Can anyone get me in the ballpark on amperage ,rod size ,wire size etc etc. The tubing is quite pricy and i dont want to frig arround to long . Its 1/2 dom steel tubing .049 wall .used for hydraulics. Its basicly all socket welded joints

How much pressure with this be subject to? A good sil-phos braze joint or silver solder joint may be better than a less than perfect tig weld.

You are probably gonna have to go with tig or "pulsed" mig welding with stitches or hold trigger for a second and then off and then another second.

The system pressure would not exceed 2800 psi.

I thought mabee mig .023 wire keep the heat on the socket and wet over into the tubing.
I think that would last longer. Then i could epoxy prime all the tubing and joint and get good protecting coverage

On that thin wall you definitely should go with the .024" wire or the smallest you can put in your machine.

Maybe a dumb question - but if this falls outside your comfort zone / welding experience why try welding - even 2800 psi is pretty nasty if it lets go & any burn through will cause havoc with flow - there are hydraulic compression fitting that are designed to do this safely whether it's to join metal to metal or transition to flexible in nearly any combination of straight / elbow / tee etc - just a thought - however you proceed good luck with the project - perhaps you could share what it is ?

Just be careful there. Stitch welding is difficult to get leak proof itself, at such small tube even worse.

2800 psi system pressure is high enough to cut thru body parts thru a pin hole.
Google fluid injected wound, not nice reading.

AndersK wrote:Just be careful there. Stitch welding is difficult to get leak proof itself, at such small tube even worse.

2800 psi system pressure is high enough to cut thru body parts thru a pin hole.
Google fluid injected wound, not nice reading.

You are right. I forgot that it was for hydraulics. Definitely do not stitch weld it. Do as complete of welds as possible.

Im building a loader for a farm tractor.
I cant seem to figure out the picture thing
Im not really out of my comfort zone i just thought someone may do this kind of work fequently and have a few tips or ball park settings. Im going to weld up a joint or 2 and pressure test them to 4400 psi which is the safe working limit of the tubing.

I can't really tell you what settings to use, but I'd have my machine at 125A and use the pedal, watching the puddle closely. I'm guessing I'd average 35-40A once the socket is hot.

Alternatively, you can do all this with Swagelok fittings (rated to 6000 PSI) and avoid the headache altogether.

Steve S

Don't forget that socket weld joints require an expansion gap. So instead of bottoming out the tube into the socket, leave ~1/16" gap for weld shrinkage.

If you must weld it, tig is the only way to go. I've done it with 1/16" tungsten and filler off the peddle slowly increasing amps till I get a puddle then modulating as necessary to avoid overheating.

I can also tell you that I have seen .049 (18 gauge?) fracture next to welds and at compression fitting olives several times due to heavy vibration and impulse loading in hydraulic applications at much lower pressures than what you will be operating at. Replacing the tubing with 1/16" (16 gauge?) fixed this every time. Specifying annealed tubing over "as drawn" helps too.

For my conscience please don't weld on hydraulic systems unless you are certified and pass all of the tests and have the correct materials to weld. Hydraulics themselves have issues without weakening. It's like welding on a tank of argon or on an old acetone or other barrel that is sealed.

AndersK wrote:Just be careful there. Stitch welding is difficult to get leak proof itself, at such small tube even worse.

2800 psi system pressure is high enough to cut thru body parts thru a pin hole.
Google fluid injected wound, not nice reading.

Yeesh! When I cut trees a hose that controls the hydro-stator that turns one of the feed rollers blew in a guys face. It sounded like a shotgun going off and had a similar effect. Very nasty injury.

Maybe fire the question off to Abom on youtube

Edit. Just saw Steve's post.

Another option.

http://www.serto.com/chen/technical-information/

I'll second for Steve's recommendation of swedge loc fittings. If it's hydraulic or high pressure gas and your using thin wall steel tube or SS. Then spend the money for the swedge loc fittings. There reusable and very reliable. We had a customer call us in to weld up some hydraulic lines for a cardboard compactor. Two guys both certified and very good, experienced welders welded on it. Stress fractures and vibration have cracked both repair spots within months after they were welded. The third time they called to get it welded we recomended swedge loc's. The next time it sprang a leak it was in a different spot and we ended up replacing all the welded joints with new tube and fittings. Hasn't leaked in two years since.