My old hymac sprung a leak on a short length of hydraulic tubing. It's not much bigger than a pin hole but is a bad leak when under pressure. Can I weld this with my mig or should it be brazed? Am I likely to ignite the hydraulic oil residue? TIA
I would braze it, because I am a lot better with a torch than a mig machine. I don't see why it couldn't be welded, if you are good enough to be pressure tight. Be prepared for the hole to get bigger when you heat it, due to rust. You probably will ignite the oil, but, unless the machine is in a puddle of it, just let it burn off.
Replace with a hose if possible.
If it's from rust, most likely you will end up chasing holes. If you can't replace it I would use a large enough patch to get to good material, whether you mig or braze. And you WILL need to clean out the scale on the inside.
What Mitch504 said .... I generally braze thin wall lines . Works fine . On thick wall lines like 1/8 inch and above I arc weld using 6011's .
Yair . . . Drum It's a bit hard without seeing the job, I think a MIG would be well down the list. As lantraxco mentions a piece of hose is a permanent fix . . . any welding perhaps not so much. I have found on such tasks that any oil in the vicinity of the braze or weld tends to make the repair porous so the pipe really needs removing, cleaning and blowing dry of solvent . . . as Blueboy says you really need to do this anyway as the heat can cause scale and rust to dislodge within the pipe. If the tube proves to be very thin and rusted I have had success by splitting a piece of similar sized tube and fashioning a patch which after meticulous cleaning can be sweated on with high grade silver solder. Here again is another situation where a TIG is real handy and would be my preferred option. Cheers.
Thanks for the replies. It's a 6 inch curved pipe that feeds the top of the bucket ram and keeps the hose off the dipper. Ill try repairing it first and, if that fails, could bypass it altogether and hope the hose doesn't rub too much.
I agree with Lantraxco, especially if all you're worried about is 6'' of line. If I had no choice or as a temporary fix I'd arc weld with 6011(my choice of welding) but as a soon as possible I'd rather have it fixed right with a new line.
Drum, follow Scrub Pullers advice if you can't replace it. The piece needs to come off the machine and cleaned before welding. If your good with brazing, go with that and a patch. Spend more time cleaning then welding and you'll do well. Mig has a tendency to make tiny pin holes that you can't see until you have oil leaking out and you need to start all over again.
I've had good results wth 7018 rods on steel hyd pipes. But as mentioned. If it's rust, you're fighting a loosing battle. Also as mentioned it should ideally come off, but as most know, sometimes and on some applications that is not always practical. Good luck, and remember, work safe: hydraulic systems retain pressure, if you do the patch, braze mig or stick, be sure to release pressure and drain the oil from the section you are working on.
Take a picture of the tube. It may be easier just to make a new one
Take the pipe off and don't be scared to weld it with the MIG, its thick pipe under low pressure (2600 psi) compared to modern stuff, flush out the pipe before re-fitting. tctractors
I welded it with the mig in the end. Too hot at first so the pin hole became big enough to stick my finger in. I welded up the hole, refitted and tested it today - so far all good. Incidentally, I was foolishly welding close to where I was charging a battery and the battery exploded. Charging battery gives off hydrogen gas apparently. Darwin Award will have to wait for another day...
That's why I suggested a patch. Welding a hole can be very challenging. I hope no one got burned. Hydrogen gas can be nasty. It blew up the Hindenburg.