How to backpurge when tig welding ss
 

First you will need some hose, here is mine all assembled:

https://i47.photobucket.com/albums/f...h/DSC07189.jpg

This is the input end, you can do it differently than I have, but these were the fittings that i had available and they seem to work well. You NEED a ball valve (for turning your back purge on and off) and the other valve is a needle valve to adjust the amount of flow coming out of the hose. I just adjust it by listening to it.

https://i47.photobucket.com/albums/f...h/DSC07190.jpg

Here is a T you will need to add to your bottle regulator. Again, I used these particular fittings because that was what was available at the time. I wanted to make mine removable as well so I added a high end quick disconnect that is designed to prevent any types of leak.

https://i47.photobucket.com/albums/f...h/DSC07191.jpg

Here is the hose connected:

https://i47.photobucket.com/albums/f...h/DSC07192.jpg

Next, gap your pipe slightly so that you have room to add filler when welding your joint. Some people like to take a piece of filler and bend it into a "V" and stick it inbetween the two pipes for setting a nice even gap and then pulling it out after tacking. For this example i used 1.75" .083" wall 304ss piping. Tack it together so it will not move on you once you start welding.

https://i47.photobucket.com/albums/f...h/DSC07193.jpg

Once you have it tacked together cap both ends with some cap plugs. These fit like a glove and are much nicer and cleaner to use than tape. They also withstand a bit of heat as long as you don't get to close with your torch. Add a hole into one of the cap plugs that the tube/hose will fit snug into so as to prevent argon from leaking back out the hole you made.

https://i47.photobucket.com/albums/f...h/DSC07194.jpg

When you get close to the end of welding your joint you will need to slip the end plug slightly off the pipe to let the argon escape or it will try to exit through your joint and that makes for difficult welding.

https://i47.photobucket.com/albums/f...h/DSC07195.jpg

I just did a single pass on this at 70 amps but with thicker base metal you can do multiple passes with purging only being nescassary on the first pass as long as you don't blow through it. The inside should look something similar to the pic below. Once you get really good, the inside should look just as good as the outside... I'm not there yet.

https://i47.photobucket.com/albums/f...h/DSC07199.jpg

Re: How to backpurge when tig welding ss
 

preventing redox ftw, nice.

Re: How to backpurge when tig welding ss
 

Great post Aaron! Just working with my fluxcore and never dealt with backpurging and never ran gas. Now I have my TIG this will be very helpful and quite informative. This deserves some sticky icky action.

Re: How to backpurge when tig welding ss
 

best way is to shove a slice of bread into the pipe near where you're welding. Don't bother capping the ---- off with real caps. Waste of time. ;D
Argon is also heavier than air, keep that in mind when working in confined spaces & when backfilling. :)


& if you get your gas coverage down close to where you're welding. It takes very little flow. 5cfm.

Re: How to backpurge when tig welding ss
 

Aaron, you're a pimp. I don't care what they say about Canadians.

Re: How to backpurge when tig welding ss
 

sticky this sucker BD

Re: How to backpurge when tig welding ss
 

Get off Aarons nuts Steve, he doesnt need you to tell him his work is an inspiration to all :6

Re: How to backpurge when tig welding ss
 

thanks for the thread.

on a side note, do you guys know of any great tutorials, beginner's guides, tips&tricks to tig welding? i don't know much about it (for example, up until now i had no idea what back purging meant lol)

thanks i'd really appreciate it!

-Luke

Re: How to backpurge when tig welding ss
 

these will keep you busy reading for a while:

http://millerwelds.com/education/library.html
http://www.lincolnelectric.com...st.asp

Re: How to backpurge when tig welding ss
 

thanks! :) read through most of it already. Good stuff, learned some important things to try next time around.

Any links on tube welding? like techniques for clamping pipe together so you can tack weld :y

thanks again, sorry to side track your thread btw. I'd take it to pm's but others may gain from it aswell

-Luke

Re: How to backpurge when tig welding ss
 

no worries. people who want to learn something will click the links as well.

for aligning pipes accurately just get a couple of pieces of angle iron, weld them on the insides of a c-clamp and bingo. just insert two pipe ends, close snug and tack weld.

Re: How to backpurge when tig welding ss
 

for the benefit of everyone reading this thread, DOWNLOAD THE FABRICATION TORRENTS IN THE STICKY ABOVE!!!!

the videos are amazing. i could watch the working with tubing one every day!

im gonna go take a hose clamp and cut a window out of it :-) tig tack welding tool FTW


-Luke

Re: How to backpurge when tig welding ss
 

o

Re: How to backpurge when tig welding ss
 

nice job

a few things handy to know

argon is heavier than air

you can literally fill a shoe box full of it and that makes for a makeshift purge chamber for items not as easy to jig up like shown above

Reynolds Wrap Extra Heavy is also very handy for purge welding irregular items

you can actually just fill a shoe box, or your grounded item wrapped in foil, with argon from your torch head and if your setup is good

the lack of constant purge flow won't hurt you one bit

Solar-Flux can be used on the backsides of stainless welds for good results. It is the gray powder you mix with methanol obtained from the Co-op or Farmers Supply place close to you. The Solar-Flux is available online and I've tried to come up with a cheap subsitution to that powder, it's just too damned expensive

like around 50 bucks for a quart can

anyone else have a home brew solution for flux powder which will work when purging just isn't possible or too difficult?

Re: How to backpurge when tig welding ss
 

for 90 thou wall

you can really do a flawless autogenous root face pass, having 100% penetration, with no gap between the pipes

makes it much easier and provides more consisitent results

one pipe with a half thickness bevel is nice but not really required in the real world

then come in and make a final fill pass with some 1/16" fill rod

your temp is high, as indicated by the gray color on the weld, bead formation is fair but looks a bit like the speed is slow in some places and extremely fast in others

you should catch on quickly