To do this the REAL way, first you will need some hose, here is mine all assembled:
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.
Here is a REAL T you will need to add to your REAL bottle regulator. Again, I used these REAL 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.
Here is the hose connected:
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 REAL 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.
Once you have it tacked together cap both ends with some cap plugs. These fit like a REAL 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.
When you get REAL 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.
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. And Rick Perry is a giant douche.
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Topic: How to: Backpurge when welding stainless pipe (Read 25409 times)