v8killaz

so I just had a quick scenario at work. I wanted to see if I can use a separate hose running argon to shield the tungsten

meaning I turn off my gas from my machine and then turn the gas on an argon tank to flow whatever cfm I'd run.

So I go about trying this, I hold the gas hose right against the tungsten from the other argon tank while my machine's tank is shut. I tap the pedal and nothing, same thing as if no gas was flowing. I try again at lower cfm and still cant get a tack weld. Basically holding the gas hose to the tungsten did not work at all for shielding. Im asking why not?

Also I got a question about purging a stainless fuel tank, first of all can I purge with nitrogen. and what cfm should I fill the fuel tank with and then how long should I wait and how many cfm should I set it at while welding. I am getting no sugaring but setting the purge at 25cfm. But the inside weld is grey. These fuel tanks are stainless steel
this is the size of the tank. all the holes are covered and gaps taped up

para pat

Your machine might not initiate an arc if it senses no gas flow.

Yes, you can purge with nitrogen but because its not an inert gas, you will not get any coloring in the weld. Use it exactly like you would an argon purge

v8killaz

yeah but the thing is it does initiate an arc.

Luserkid

For your machine arc question, are you holding argon hose from the side to side of your arc or did you hook up your torch to that extra bottle/argon source? If its side to side you probably wont get a good arc because the argon is blowing out your arc from left to right oppose to up and down. What you could do if your machine isnt releasing gas correctly is hook your gas line directly to your argon. The problem with doing this is that you will waste alot of gas between welds and what not.

For your purge question are you talking welding from the inside out or the outside in? From your pic it looks like inside out and if thats the case you could make a little purge box and tape it to each spot your welding on for the time then move to the next. If you do the box I would only run about 15cfm or so as the box will do most of the work. Now if your welding outside in depending on the size of the tank i would do full blast argon from bottom with exit on top for 10-30 mins. while rotating the tank so argon can get to every corner and area before letting it sit. Then set it down to about 35-40 depending on how big the exit is and how sealed up the part is.

v8killaz

yeah im holding the gas hose to the torch(tip of the tungsten). I guess you right, doesnt make too much sense to me but whatever.

and im purging the entire tank. and welding from outside, thew welds inside are just all the baffles and whatnot

Engloid

Purging with nitrogen really won't give a nice clean color. It can prevent sugaring, but if you are worried with color, go with argon.

v8killaz

alright. im having better luck now setting purge lower cfm like 10cfm and making sure the other leaks are sealed up expect the one im welding. less arc wander with lower cfm and better penetration and color.