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

 

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

 

how do you do that?

 

yea im curious too

 

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

 

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.

 

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

 

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.

 

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.

 

thanks for the info now im starting to understand