Nalla,
Welding FCAW in an open root joint without backing strip or backgouging is definitely not recommended,
Regards,
Shane
Nalla
It sounds like your asking two seperate questions
I agree with Shane that full pen butt welds with no backing or backgouging is not generally recommended with FCAW.. The penetration is too great which makes open root control difficult... Has it ever been done? Yes. Is it recommended.. No.
Can FCAW really achieve sound multi pass welds in the overhead (4G) position? Yes!
FCAW when the proper electrode is chosen and the manufacturers suggested parameters are obeyed out of positon FCAW welds can be done with the highest quality results and some pretty amazing deposition rates as well...
Dear Friends
Back in our yard, FCAW in 4F position only. 4G-tried but welder finding it control weld puddle. Appreciate if someone can provide more detail on 4G position welding technique using FCAW
Thanks
Nalla,
Unless I'm missing something here, it seems to me that the place to start is with more information.
Because this is a difficult operation to perform successfully it is very detail oriented. So:
1) How thick is your test material?
2) What grade material are we talking about?
3) What wire specs are involved? Diameter, EXXT-X (is it an all position wire? Second 'X' will tell you.)
4) Are we talking Dual-Shield (flux-core with gas) or Innershield (flux-core without gas)?
5) What is the bevel angle, root face, root opening?
This info would help to be able to give more advice.
Have a Great Day, Brent
AWS D1.1 2.17.1 spells out that groove welds made from one side without backing are prohibited except for welds in secondary nonload carrying members, and corner joints parallel to the direction of calculated stress between components of built up members.
That restriction is for procedures that are Prequalified (clause 3) only. My code contains the wording
".... that has not been qualified in conformance with clause 4 shall ..."
I have performed open root welds with FCAW in training booths. It is similar to 7018 Open roots in that its very unforgiving of joint dimension variations, heat buildup and tie ins.
Here at my shop I encourage my guys to attempt the root pass as if they are not able to place a backing strip or back gouge..... Only a few have ever been able and when I say a few I mean 3 out of.... say 300 who I've personally tested. No I don’t fail them if they don't but I like to see them try... And yes I’m one of those three who can do it. But anyways.... It’s not a recommended practice. I just want them to get good penetration so they aren't spending an hour back gouging. D1.1 doesn't require it as of now but maybe in the future as more and more success and advances with the FCAW filler material is accomplished. A lot of inspectors will write there WPS's with duel processes because they are using FCAW and the ability to use a backing strip or back gouging isn't possible. The initial root pass will be something (GMAW, SMAW, etc.)Other than FCAW and therefore will be considered your backing. But if you can do it and your consistent at it....make some bets and make some money...
i have seen many welders certified with .045 FCAW E71T-1 on 3/8" plate for ASME application. Never tried it myself, though I used to be certed 3G & 4G unlimited with plate. The trick is heat control and correct fitting. Heat control is easier done with .045 than .052.
4G FCAW is easier run than 3G, in my opinion. 4G uses a similar heat and wire speed, just a bit below 3G settings, and the wire should not be dragged or your welds will be ropey and hard to slag. The gun nozzle should be at 90* or even slightly less, pushing overlaying passes just a bit once you have enough material on to get the background heat up.
Topic American Welding Society Services / Technical Standards & Publications / FCAW without backing strip
