Question for pipe welders.

[Shield Arc]

Tig welding open root. 6G position. 6-inch sch. 80 pipe. 37 1/2 degree bevel, knife edge. 1/8-inch gap. 1/8-inch filler. 125-AMPS, walking the cup. Miller Dynasty 300.
Never had much of an opportunity to Tig weld pipe. Union thing!
Do you pipe welders think this Tig root would pass visual?
Thank you for the help!

 

[Gary Fowler]

Hard to tell much by the photos other than the excessive penetration (lumps and cold wire looks to be about 1/8" high and 3/32 would be all that is allowable) in a couple of spots. Looks to be some IF at 12 (likely tie in at a tack.
I guess it would depend on the inspector and how smooth he wants it to look. Other than the couple of drop thru (EP) and the low bead at 12 which is hard to tell if it is IF (inadequate fusion of the root) or just a low spot it looks pretty good. A low spot like that when every thing else is heavy root would show up really light on an xray and might be rejected without visual conformation which you may not get on the test. I was always a little lenient on welders with regard to root reinforcement as long as most of it looked good but I have seen inspectors that were real hard axxes and wanted everything perfect ie, top bottom and sides identical.

Fitup seems to be OK per your description so you may have been running a bit on the hot side which caused the EP and drop thru.

 

[Shield Arc]

Thanks for the reply Gary, I was hoping you would see this thread!:thumbsup:
I seem to do the best if I melt the filler rod off, just about the same size / width as the filler rod.
Being a structural welder, never had a lot of opportunity to do this kind of welding. I'll keep at it, and see if I can get more consistent.
Thanks again Gary!

 

[Gary Fowler]

The secret to perfect beads is smooth and consistent feeding of the filler rod which takes a lot of practice. You need to keep the end of the rod in the puddle especially on the bottom and use the rod to hold the puddle up by feeding it from the inside. In order to do this, the gap must always exceed the diameter of the wire. I always gapped 6" so that I had a loose 1/8 gap after tacking and never put more than 3 tacks on the pipe if I was allowed. Start on the side without a tack and weld it first (no tacks to worry about tie in issues). Feather edge all your tacks on both ends. Some welders will feather edge each stop before starting to weld again as this makes for a smoother start up with less likelihood of a drop thru because of staying in the tack too long to preheat.
RUN the bottom half on both sides before the gap closes. You may have to go to 3/32 wire for some of the bead if it closes up on you to where the 1/8" can no longer be inserted. You kinda have to start with the wire on the inside so the bottom of the wire is flush with the inside of the pipe and transition as you go up to where the bottom of the rod is flush with the outside of the bevel. Don't know if I am explaining that right. Learn to feed the wire from the inside on the SS because on the alloys listed below, you can only weld them by feeding from the inside.

Different alloys demand different techniques with SS being the most flowable and most forgiving of a mistake. Inconel, Alloy 20, Hastelloy, Titanium and Zirconium are least forgiving and each has a different technique to use for welding but all of these is a one shot deal, get it right the first time or cut it out and start over.

 

[Tractor Seabee]

Carl, Gary has some excellent advice. I never got into TIG in heavy section steel. Always a fitter not a welder for TIG. TIG welders were the Prima Donnas of the building trades welders. In my day TIG was reserved for SS and exotic metals and thin wall pipe and tubing; never plain ole steel. Its an age thing again, Gary is probably a lot younger than I am. Knowing you; you will soon have it mastered. What a waste of Argon though. Maybe you should have a liquid argon tank in your shop so you can get the price break and you will have Argon for the rest of your life.

Ron

 

[Shield Arc]

The last time I did this type of welding was in the 1970s. When I worked for Lents Fab shop in Bremerton. Our number one contract was building nuclear waste tanks. The company sent me to Olympic College to learn how to Tig weld stainless steel pipe in the 6G. We had a couple guys who were fantastic Tig welders, so I didn't do much Tig welding. I just thought I would try my luck at it again. I've always been impressed with guys who could do this type of welding.
In my opinion, pipe welders are the best of the best!

 

[dragoneggs]

The last time I did this type of welding was in the 1970s. When I worked for Lents Fab shop in Bremerton. Our number one contract was building nuclear waste tanks. The company sent me to Olympic College to learn how to Tig weld stainless steel pipe in the 6G. We had a couple guys who were fantastic Tig welders, so I didn't do much Tig welding. I just thought I would try my luck at it again. I've always been impressed with guys who could do this type of welding.
In my opinion, pipe welders are the best of the best!

Before I met you Carl, I looked into taking a few night classes at Olympic College but I found out their curriculum was suited for serious welding accreditations. I was looking for the class for hacks. :laughing:

 

[Shield Arc]

Did another joint this morning. I knew Gary would give great advice:thumbsup:. I dropped down from 125-AMPS, to 120-AMPS. Really seemed to help.
As you can see in the picture of #6 I had lack of fusion, from 6 to 3. From 6 to 3, and from 3 to 12 you have to weld left handed. My eye sight isn't what is use to be, so I missed this section. It's going to take some time to get consistent with width, and reinforcement!

 

[4get gto]

Just curious why tig and not stick or even flux core mig. I did a lot of 0.45 flux core on pipe back in my day. Just nosey is all. Is it ss or steel?

 

[Shield Arc]

It is a very common welding test. Tig root, and hot pass. 6010 fill, with 7018 cap.
If you punch through the root and hot pass with the 6010, test over right then, and there.
It is steel pipe.