[88MOOSE88]

Hi, everyone

I'm an apprentice pipe welder, I have passed 2 codings both in full tig, I am currently trying to learn the through the pipe technique in 6g, where you hold the filler through the pipe and build a bead inside the pipe.

I've watched loads of videos on youtube, especially a user called fieldres. What I find hard is keeping the filler in the pool it's hard to keep the surface tention for any longer than a couple seconds.

I mainly weld stainless steel pipe.

I've asked my mentor at work but he doesn't say much about it, he always does the dip method. I've just noticed that you can build better reinforcement when in the 6g position.

I'm one of those guys who prefers a heavier root rather than a shallow blend in on root passes

Any tips on amperage or just general technique


Thanks

Brandon "moose"

[Otto Nobedder]

Brandon, in the U.S., that technique is usually called, "back-feeding" the root.

I've never done it. Most of my welds require flat to slightly positive penetration, when root penetration is critical.

There have been some discussions of it here, so try using the search with the keywords "back feed", and see what you find.

Steve S

[coldman]

First of all I would urge caution in trying to lay too thick a root pass, this is the most common cause of lack of fusion or cold lap in root passes. You can use second or third passes to really boost fill but there are no short cuts with consistent root passes in my experience.
Root passes through the pipe works great and I would use the same amp settings as would normally be used for dip technique for a given prep gap and land. I normally leave the wire in the weld pool to prevent keyholing and the trick here is to keep the arc length tight and travel speed consistent with a slight weave. Strangely enough this is not hard to do. I was never taught this technique but because of access difficulties on one job it seamed logical to try it and it worked a treat. Since then I have used it quite a few times and practice it sometimes if I don't have a need on the job just to keep up a bit of memory.
Go for it!
The other tirck is to hold the torch with the back cap between the index and third fingers (at the bottom of the fingers) for good control.

[88MOOSE88]

Thanks for the advice guys

I've tried the technique with mixed outcomes, do I aim the filler into the arc or pool and how do you build metal on the inside of the pipe when welding overhead.

But I can't seem to find a balance on the surface tension with the filler rod and it wond build on the inside.

[coldman]

You need to keep the rod at the front of the weld pool where the arc is. You need to keep moving otherwise you will keyhole and it will all get out of control. In my experience, this technique does not result in extra reinforcement. If this is your requirement you are better off welding from the outside of the pipe and pushing through or laying the wire flat but more inside the joint and wiggling the torch.