Not all flux core wire is created equal. We have had excellent results with Esab 7100 LC and 75/25 gas. It has a thinner sheath, so there is a bit more amps for the same WFS as some other 052. Great puddle control, soft arc, no spatter. Ended up using 052 wire for all position welds on pipelines.

7100 was a bit of aproblem to get, so the contractor is now using Corex Vision AP70. Also very good results.

All the welding is to B31.3/Asme IX; most have 100% RT. Repair rate is very low, around 2% last time I looked.

If the pipe you are welding is for sour service, it would be good to get ahold of NACE RP 0472. Many E71T-1 wires will not pass the hardness tests for sour - qualification is by brand name, (and possibly gas mixture ?).

Only problem we ran into was one batch of wire would not feed - it got wound on the reel in a bad manner.

-20 F with unheated 75/25 bottles was also a bit of a problem. I think they had to change regulators or some other small fix.

FCAW is, in my own humble, if ever-so-biased opinion, the way to go.