I need some opions on a subject, that should'nt be to hard to get here. lol
I work for a pipe and vessel shop. Every pipe joint and vessel penetration and joint is welded, root, hard wire dn hill and duel shield fill and cover. Buy the way every body in this shop calls duel shield, fluxcore, very confussing when I first started there. They are adament about welding all structural elements we build with duel sheild. I hate the stuff. Its messy, smokey. When I weld with it, it looks like the puddle is just laying on top of the base metal. They must be doing something right because we have a 2-3% faliure rate on xrays and are hydroing anywhere from 800 to 5300lbs. I can't get anybody there to give me a good reason why they are so hard core about this processe. The ony thing I see good about it is its deposition rate. My ? is why not use hard wire all the way out? Is it stronger then hard wire? I know the ship building industry uses it. Can anybody give me good info on why its better than hard wire. Thanks so much.
You will probably get more/better information from some others, but I will get you started:
Solid wire will only weld out of position in short circut transfer or with a really good pulse systyem.
You did mention the deposition rate, and that is likely the main reason for it's use, time being money & all that.
Most of the dual shield wires have really good mechanical properties, but low alloy solid wires have good specs too.
Anything over 1/4", I would use dualshield, metalcore or 7018. To get the penetration you would with the other processes, you would have to run the hardwire temps fairly high, which would mess with the metallurgy of the wire and the welds could potentially crack. Don't quote me on that though :).
By Lawrence 
Date 01-01-2010 21:59
Edited 01-01-2010 22:04
Dual Shield FCAW can be run in *all positions* with the same high deposition rates that solid wire with spray transfer can be run .. But solid wire can only be run in the flat position... Like Dave said ... Some high end pulse units can run solid wire in all positions but they will not be as productive.. Pulse (with steel or Metal core) can't run out of position at high wire feed rates.
FCAW also has a deeper and more hemispherical penetration profile than spray transfer solid wire, This has to do with current density in the tubular wire and assistence from the chemicals in the flux...,, So for structural fillets FCAW often can be run with a smaller design weld size if process controls are in place... Furthermore.. FCAW deep penetrating ability allows for reduced groove angles in beveled joints which can allow for reduced time, filler and distortion.
Find out what specific brand of FCAW electrode your using and go to the manufacturers web page and look at the suggested operating parameters... Most likely they will fall withing the limits of your WPS and will put you right in the ball park for minumum spatter, smoke and undercut... The voltage vs WFS performance for different brands of FCAW electrode can be significant so it's best to go right to the vendor to get started... It might make your FCAW experience a whole new game... much more fun when things work as advertized !
Edit: My post refers to properties related to gas shielded FCAW (dual shield)... Self shielded FCAW has many differences, among them are performance, penetration and deposition rates.
By Blaster 
Date 01-04-2010 01:55
Edited 01-04-2010 04:37
Hi dep in all positions on steel needs slag to support to big fluid puddle.
Dual Shield (not "Duel") is an ESAB trade name for their gas shielded FCAW electrodes. Lincoln calls their gas shielded FCAW electrodes "Outershield".
