FCAW root pass

Date 02-28-2008 16:14

Yes its possible. It been done. I've done it myself on roll outs playing around. Not in position. The puddle is quite runny for obvious reasons. And you have to deslag.
I had to run fast and off the top oscillating fast and not carrying much metal in order to avoid dripping through.
It, in my opinion is not recommended however. And I see little advantage to it. Some in here may have more experience with it.

By chall

Date 02-28-2008 16:17

My experience has more to do with client specifications. I've not seen any client who would accept open root FCAW on pipe without backgouging (for the reason you elude to - it's very questionable).

Charles

By GRoberts (***)

Date 02-29-2008 00:50

Even though it can be done, I don't think it is very consistant, or that there are many welders capable of it. It is easier with self shielded FCAW though.

By dlmann

Date 03-01-2008 13:54

Thank you for your replies gentleman. I keep in mind that just because I haven't seen it, does not mean that it cannot be done. Every pipe weld I have ever seen had a GTAW or E6010 root. In this project, all welding was bid to be done with FCAW w/gas per AWS D1.1. The vendor submitted his FCAW w/gas WPS and was accepted. Nothing in the drawing, PO, or specs addressed pipe weld. I think I missed an opportunity for improvement here. I should have challenged it and made sure that that these pipe welds were what the client intended. I'll know better next time.
Regards Donnie Mann

By weldgault (**)

Date 03-03-2008 17:53

TKY connections on offshore platforms and AWS, D1.1 6GR with .045 Gas shielded FCAW is a requirement, on the Gulf Coast. This is an open root and is done all day with no problems. John

By Kix

Date 03-03-2008 18:09

A weldgault, do they shoot these joints after they're welded? A flux-cored root pass can be done pretty consistent when the welding symbol only calls out for partial penetration.;-) Not saying that offshore rig welds are called out this way, but i'm just sayin in regadrs to the original topic.

By weldgault (**)

Date 03-03-2008 18:20

Read TKY joints, in the D1.1 AWS books. It is not that long. I have taught this for the last 15 years. John

By GRoberts (***)

Date 03-04-2008 16:47

As we are working on quite a few TYK joints right now, it is true that .045 FCAW-G can be done open root CJP without a problem. However, AWS does not limit the melt-though on the back side of the joint. If this was limited, as is normally the case with butt joints that are fluid containing (instead of structural as is the case with TYK), I think it could be another matter to get consistancy. In out limited experiments, we could only get consistant melt-though on the back side of butt joints with rotated pipes in the horizontal position. I'm not saying it can't be done, it just seems harder than most of the FCAW welders are capable of doing consistantly.

By Kix

Date 03-06-2008 13:47

They do it all the time in the shipyards, but with ceramic backing. I worked on open root seams for awhile at ESAB and they told me it couldn't be done with the wire that was used in industry at that date. They did say however that they could design a wire that would run open root flux core consistently, but it would be too costly and they wouldn't be able to sell enough of it to make a good ROI.