GTAW welding - puddle fizzes

[PontiacRacer]

I'm TIG welding 4130 on a new roll cage. Every once and a while the weld pool will bubble and fizz and spew like a sparkler. Metal is ground clean and wiped with brake clean so I'm thinking its a gas coverage issue. I'm using a gas lense with 7/16" cup, 3/32" red tungsten, 13 cfm gas flow. Tried cranking the gas up to 16-17 cfm and didn't help. Can someone help me?

Thanks,
Craig

[chris madden]

Are you drilling a hole close to the weld so the hot gas in the tube from the weld can vent if not it is venting through your weld and pushing up your weld. make sure you have 1\8" to 1/4" hole drilled close to the weld area to vent.

[Fishy Jim]

You don't need the hole close to the weld. You just need to make sure the joint doesn't create a sealed chamber. The hot air getting out farther away from the joint would probably be preferable.

1/64" hole would be sufficient. For practicality sake, you'd make it bigger just to not break bits.

After the weldment cools, you can then go back and fill your breather hole.

[PontiacRacer]

Typically I do use a hole at the tube intersections to allow the heated gas to vent out of the tube I'm working on. I have had the puddle blow out on me a time or two where I didn't drill holes and got to the end of the weld. This wasn't one of those cases though, I was actually welding up a vent hole on a piece of tubing about 4' long. The tubing was all cool and the instant the arc started it started to fizz and piss like crazy. Couldn't have been any gas pressure in the tubing that quick....something else was going on. It acted similar to when I use a standard 3/8" cup without a gas lense and have too much stick out (ie. poor gas coverage).

Craig

[Fishy Jim]

Any chance of contamination in the area?

[Laiky]

In practcing my 4130 tube welds i saw this problem too. I had switched to a #8 cup on my gas lense from a #6 just to see if it helped any, i increased gas flow but it didn't help much. Returning to the #6 solved the problem. I'm guessing there is a relationship between the diameter of the tubing and the size of the cup. Maybe too big of a cup lets the gas flow around the tube and pull in air. At least thats what i think happened.

[Billet Benny]

This wasn't one of those cases though, I was actually welding up a vent hole on a piece of tubing about 4' long. The tubing was all cool and the instant the arc started it started to fizz and piss like crazy.
Craig

There's your problem. Welding up a vent hole is tricky. If you try and hold your arc over the vent hole atmosphere will meet arc. Gas cannot flow through the hole into the tube because it is filled with air and that air has nowhere to go. This collision is going to stir atmosphere from in the tube into your arc/pool, etc. Normal and expected occurrence if you try and start a puddle right over the hole.

Any other times?

[LAN]

Try cleaning the area that you are welding with scotchbrite (no chemicals) before welding. 4130 tubing typically has a thin mill-scale on it. If you take that off you will notice a huge difference in your finished bead cosmetics and the way that it welds.

Good luck man

Brad

[Vicegrip]

Heat a section of the tube away from the vent hole with a heat gun or torch. Almost too hot to touch is good enough. Get ready to close up the vent hole and drop a wet rag on the heated section of tub. This will make air want to go in rather than coming out of the vent hole. sometimes I skip the vent hole and stop the weld and let things cool off some. I find that can close up by ether welding the last bit fast or doing the heat and wet rag trick no vent hole drilled.

[MrRXL]

I had the same exact problem when I was using brake clean to clean oil off of new steel. I discovered when I used mineral spirits or a water soluble cleaner the problem went away. One day I was out of mineral spirits and I used brake clean and the problem came back. Brake clean gets into the steel and any welding process will cause the expanding gases to blow out the weld puddle.
Hope this helps.

Best regards,