[Otto Nobedder]

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

[LtBadd]

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.

[Coldman]

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.

[Farmwelding]

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.

[PeteM]

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.

[Harry72]

Maybe fire the question off to Abom on youtube

[kiwi2wheels]

Edit. Just saw Steve's post.

Another option.

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

[Poland308]

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.