Welding Tips and Tricks

Hey all, I'm a somewhat newby welder working on a crack on my small air compressor. Where a support was welded to one of the air tanks a crack formed and allowed air to leak. I thought it would be a simple matter of running a bead over the crack, but no matter how many times I weld it, new cracks form, generally alongside the bead. I've tried various voltages and speeds, and can tell I'm getting good penetration, but after several passes I've still got an air leak. I'm using a new Everlast 140 inverter welder with flux core wire. The tank steel appears to be about 3/16"

I'm also getting some really nasty pops while welding, sudden extremely bright flashes that even the welding helmet can't dim down, and there tends to be craters left behind from these, some of which also leak air. These are much, much brighter than the ordinary arc.

Any advice on how to proceed? I once watched a guy try to fix an air leak on an classic alloy wheel, and every time he tried to plug a pinhole, new ones opened up beside his weld, and it's almost like this is whats happening here. He blamed the quality of the casting but I don't know if that's what is happening here.

throw the tank away before someone gets killed.

i don't think you realize that when they crack they split, often split apart enough that it can launch the whole compressor across the room. people have been killed by this before.
this is why they get hydrostatic tested after welding.

this is also why you do not weld on compressor tanks, especially by newbies.

buy a new tank!

Rattlenbang wrote:
I'm also getting some really nasty pops while welding, sudden extremely bright flashes that even the welding helmet can't dim down, and there tends to be craters left behind from these, some of which also leak air. These are much, much brighter than the ordinary arc.

thats probably compressor oil which is soaked into the steel.
not sure if you could even wash it out.

Agree, throw it away. If you are going to do something, you can get another compressor with a good tank and a shot motor and swap the gear off your one.

Thanks all. In retrospect, the danger should have been obvious, but when 1) a guy has a new welder, 2) You're the type that fixes absolutely everything, it's not always the first step to stop and think, "Should I really be doing this, even if I can?"

Appreciate the knock on the head "Hello, hello, anyone home?"

The metal is likely fatigued from vibration. Pressure vessels fall under r stamp repairs. Paperwork to make a repair like that costs about $1500 before you even do any work. If I was doing it for work( and I do). They would tell you to cut out a section of material and replace it. Materials all have to be documented with heat numbers, both patch material and any fillers. This kind of work is very serious. For good reasons most already mentioned.

I don't have much to add, but the first thing I noticed was the machine you were planning to use is way under powered for that type of repair, IMO. I would think a 200 amp machine would be minimum for that type of repair. I could be off base.

You could do a code weld with 3/32 7018 at about 80 amps and it would be fine.

Poland308 wrote:You could do a code weld with 3/32 7018 at about 80 amps and it would be fine.

Yes you could, but he stated with flux core wire. Can a flux core welder function as stick? I thought mig was cv vs being cc?

Spec sheet on the everlast 140 says it can do .25”.

Don't know how small is "small" but I rebuilt my sons small compressor with a rusted out tank by replacing it with a new truck air brake tank about the same size from a local heavy truck repair shop. Had to weld in one inlet fitting and swap out the mounting hardware for the pump and wheels.

Rattlenbang wrote:Thanks all. In retrospect, the danger should have been obvious, but when 1) a guy has a new welder, 2) You're the type that fixes absolutely everything, it's not always the first step to stop and think, "Should I really be doing this, even if I can?"

Appreciate the knock on the head "Hello, hello, anyone home?"

"just because you can doesn't mean you should".
very hard lesson to learn and many have not gotten a 2nd chance to do so.
had a guy here who tried welding with acetylene and oxygen in the same bottle. pretty sure he also ignored people online who told him not to.

homeboy wrote:Don't know how small is "small" but I rebuilt my sons small compressor with a rusted out tank by replacing it with a new truck air brake tank about the same size from a local heavy truck repair shop. Had to weld in one inlet fitting and swap out the mounting hardware for the pump and wheels.

please don't encourage them.
you may have done a perfectly fine job, but you won't know without hydro testing.
that could sit around for decades and long after you have forgotten what was done, a marginal weld finally lets go and shoots it through the garage wall.

the worse thing is it could be passed on to some else. here is a free compressor for the shop class at school.

seen a few write ups where people have made their own hydro testing rig and actually tested their work.
not exactly legal but at least they have proof its safe.

Was the combo gas guy trying to save space or visit space?

weldin mike 27 wrote:Was the combo gas guy trying to save space or visit space?

bits of him got into low orbit
but seriously no idea what he was trying to do. i suspect he knew someone with big bottles and could not shift them to his place.
sadly he was alive for a little bit after the explosion. not a nice way to go

He was a summer kind of guy. Summer him here, summer him over there...

old Cletus tried to do something "intelligent" and ended up clearing the roof of a 50 foot barn. Hit the ground on the other side and looked like he came right out of a cartoon of the roadrunner and coyote.

weldin mike 27 wrote:He was a summer kind of guy. Summer him here, summer him over there...