back purging???
 

im a newb at welding and noticed people talking about back purging stainless...what is back puging.??? :8

Re: back purging???
 

having the back side area of a weld filled with inert gas, like filling a pipe with argon before you lay a bead on it

Re: back purging???
 

how do you do that?

Re: back purging???
 

yea im curious too

Re: back purging???
 

stick the nozzle in the tube and tap the pedal w/ ur hand covering the other side so gas flows in

Re: back purging???
 

lol... try using some type of cover for the tube so ud on't have to use ur hand. When tigging, u need both hands. painters take (blue) i heard works really well. introduce the gas and start welding. low flow rate tho or ur just be wasting gas.

Re: back purging???
 

do you get better penetration or is it that the weld just have less debry in them.

Re: back purging???
 

i'll try to do a write up with some pics on back purging later this weekend if i can find the time. there are a few different ways you can set it up. the advantage with back purge welding is that when you weld ss pipe at full penetration, you don't have any contaminents getting into your weld inside the pipe making it a stronger bond throughout the weld. for making manifolds it probably isn't that critical though, but proper technique when welding will always ensure secure welds that don't fail.

Re: back purging???
 

I notice at work when the welders are tig welding up pipes for us he uses a paste of some kind on the inside instead of back purging.It is a flux of some kind.These are stainless sch 10 pipes in big sizes like 6" 12" etc.What would the draw backs to a flux vs back purging?I meant to ask one of them but i forgot.

Re: back purging???
 

thanks for the info now im starting to understand :y

Re: back purging???
 

That's SolarFlux. It sucks ass. I wouldn't use it for anything but drain piping or bullshit like that.

When purging, you don't want to hold your torch in the pipe and blow argon in it. You want to have a splitter on your argon hose, or another bottle. Tape up all openings on the pipe. Punch a hole in one end and put an argon hose in it. Punch an equal sized hole in the other end. Allow argon to flow through until the exiting hole flow will put out a lighter flame, maybe give it a few more minutes, just to be sure. Then weld the joint you need to weld, removing the tape from it as you weld, not all at once. Otherwise, all the argon will flow out the bottom and you will lose purge.