[weldit321@gmail.com]

I am getting small pinholes that leak on some 3003 aluminum that I am welding into fuel cells at work. If i go back over the welds it usually fills the pinholes but it is time consuming and I have to seal the tank to test for these. I have brushed the surface of this weld to better see the pinhole.
4043 filler rod

Would backpurging the tank help with this ?

[Rick_H]

That is a pin hole....any clue what is causing it to surface, rest of the weld looks very clean.

[weldit321@gmail.com]

That is a pin hole....any clue what is causing it to surface, rest of the weld looks very clean.

That is why I'm so baffled, It is randomly happening on welds like this where a small impurity or bubble (guesses) floats to the top and causes a leak in the fuel tank =/

[Poland308]

It's possible back purging will take care of your problem. But beware if you turn the purge up to high on a sealed tank it can also cause this kind of random pin hole. What do you use to cut your sheets. Is it possible something is getting embedded in the edge of the sheet when you cut. I.e. Steel, grit from a wheel , or cutting oil.

[weldit321@gmail.com]

It is a water cut material, and I usually clean with a 3m scotchbrite roloc pad before welding on a die grinder.

[motox]

did you try swapping out the tungsten?
craig

[Otto Nobedder]

It is a water cut material, and I usually clean with a 3m scotchbrite roloc pad before welding on a die grinder.

This "can" be a problem. Dressing with a Roloc gets the pad warm enough to leave plastic residue behind. I prefer a fine stainless cup brush in my die-grinder to Scotchbrite.

This may not be your problem, but it's worth experimenting.

Steve S