TIG burn through on 16ga steel for sumping my gas tank

[BOOSTIN21]

Im building a sump box for my stock tank. I am using 16ga steel sheets. The sides are all made up and the back and bottom piece i managed to keep all one piece by just bending it. I went to tack it and the two ends got tacked fine but when i went to tack near the corners... bam! It blew through.
Im using 3/32 tungsten and im thinking thats my problem. I think i need 1/16 tungsten. Heat was set to 54.
Help!

 

[92awdgsx]

1/16th would help. It could be some dirt too. It's hard to say, I would have to be there.

 

[99gst_racer]

Tungsten size shouldn't really affect burn through much at all, right? Tungsten diameter is all about amperage capacty I thought. And the grind of the tip is what affects bead width and penetration.

OP, is it a tight fit or are there gaps? Maybe try focusing more heat into the tank rather than the sump material.

 

[talonalex92]

Ive always had good luck with heli-arcing gas tanks and sumps.

 

[turboglenn]

Use 1/16th tungsten.. if you're welding SS use ER309L and if you're doing mild (i doubt it) use Er70s2

NOW, heat should be no more than about 40 amps on SS, and probably the same on mild.. Thing is that edge builds heat FAST so 50 amps turns into thje heat of 70 FAST.. I'd use fourty amps, then be backing off to about 25 by the pedalbefore i was done... I'd also weld in 1/2 to 2/3rds inch increments jummping around from cool spot to coolspot, but that's just my technique

 

[Gamble97]

1/16th is ideal but I do 16g with 3/32 because that is my gas lens size that I have.
I agree you were probably too hot. Have you seen Jody's videos where he moves the torch back and then dips. Maybe that would help? Also corners are tricky that is for sure!

 

[BOOSTIN21]

I should have been more clear, my apologies. As soon as I got out of the shop I was very bothered by how things went in the last few mins of me trying to tack the box together, so I posted from my phone.

I am not welding onto the tank at the moment. I am just tacking the sump box together. I am planning on making a bunch of boxes ready for 1g DSM tanks and hopefully become a vendor/freelancer here soon.

So the material is 16ga. mild i believe. I got it from a local hardware store. (slim pickings when on short notice).

There were some small gaps but where I was tacking the pieces were touching.

Now that I think about it, it could be contaminants on the metal as I finished forming the box and sides and immediately went to go tack them.

Tungsten never made contact with anything and was sharpened with the length of the shaft. I was using a #7 cup also. I had better results back when I was tig welding more often and would use a #6 cup.

 

[Gamble97]

Maybe it just got too hot? Were you backing off the puddle as you got closer to the end?

 

[FIBA M - EC17PSE]

Tungsten size shouldn't really affect burn through much at all, right? Tungsten diameter is all about amperage capacty I thought. And the grind of the tip is what affects bead width and penetration.

OP, is it a tight fit or are there gaps? Maybe try focusing more heat into the tank rather than the sump material.

Amps still plays a part in the heat exchange in the cycle! Use a big tungsten then you use more heat at a wider area same goes with aluminum but its harder with aluminum i use a 2.4mm tungstan on anything upto 4 mm on ally and 2.6 on stainless. I use a foot pedal so i crank it up to 200 or 160 for ally and go from there. 100% make sure the area is clean as contamination will eat it up and not help you or seal very good. Im not all up on the american sizes etc etc still yet to learn them . If i was you put your amps to 30-34 and go slow from there. Saying all this you use helium right? Where as we use pure argon gas so i guess you burn hotter anyway. Hope this helped abit

 

[BOOSTIN21]

I had heat up over 70 at first and when i realized that i dropped it down to about 53-54. I couldnt even get a puddle as it just burned through right away, or I could get a puddle to start on either piece but once i tried to join them is when it burned through. I even lightly applied pressure to the pedal and tried to blip it to form a tack, but that was a no go as well.

 

[FIBA M - EC17PSE]

I had heat up over 70 at first and when i realized that i dropped it down to about 53-54. I couldnt even get a puddle as it just burned through right away, or I could get a puddle to start on either piece but once i tried to join them is when it burned through. I even lightly applied pressure to the pedal and tried to blip it to form a tack, but that was a no go as well.

You have to be very fast on open corners and 3 corner areas. You can start a few inch's in and then go back to the corner section, if that is possible. I do this with ally as it helps to not blow through. You say you had it low but not producing the pool for it well if you hold it there it will go but it takes its time. Try to go 43 amps then and go from there and see how you go with that. If you can stick a block behind the part your welding to help minimize it and that way you will also aid in penetration.

 

[Gamble97]

Seening how it's a corner, can you put a piece of aluminum angle behind it to take some of the heat? Or copper would be even better.

 

[BOOSTIN21]

its not really a corner. i will have to get some pics up to show you guys how I'm doing this.
the crazy part is, I was welding some 14ga. just to see where my hands were at as far as steadiness goes, and everything was peachy. i will try and snap some pics and then we can go from there.

thank you everyone for all of your input.

-Cullen

 

[turboglenn]

((gst_race...tungsten size also plays a a big part in how well amperage is transfered and to what amount of area it spreads to (just as in how you grind it does) anything under 150 amps i use 1/16th

and if all you have is a 3/32lense, put a 1/16th collet in there,works in a pinch and i do it when i get a worn collet and can't get to the welding shop

 

[Gamble97]

its not really a corner. i will have to get some pics up to show you guys how I'm doing this.
the crazy part is, I was welding some 14ga. just to see where my hands were at as far as steadiness goes, and everything was peachy. i will try and snap some pics and then we can go from there.

thank you everyone for all of your input.

-Cullen

Eat some bread or something before you weld. The carbs help keep your hands steady.

 

[BOOSTIN21]

i think i told you that back when you started getting into welding. .

 

[Gamble97]

Maybe but it helps!!

 

[BOOSTIN21]

It sure does help. Keeps your blood sugar in check.

How are you guys swirling your puddle?
Like:

))))))))

or...

/\/\/\/\/\/\/

or...

00000000

 

[Fehrion_sit]

^^^^^^^^^^^^

i agree with BOOSTIN21 ... try weaving and a let off the peddle after you strike an arc ( if you are using a remote peddle). your puddle should be no wider than twice the filler rod and if you start to undercut, stop and turn down the heat till you get it right, practice makes perfect