GRoberts,
I don't want to hikack this thread, but I haven't seen any activity on it for a few days now and I'm curious about FCAW and high voltages relative to amps, and with high travel speeds. I've thought maybe these were causing worm holes with a particular welder that I would notice with his machine set up this way(ie 37-39v and 325-350a with 1/16" E71T-1 100%CO2), but don't have a firm answer in my mind about these parameters being a cause of his piping porosity. It has been talked about in other threads here on the forum, but I haven't heard any confirmation to my theory. I see this guy finish welding his end waaay ahead of his partner on the other end of the same material with approximately the same amount of weld to be placed. Of course his boss would pat him on the back for making quick work of his end, but then he would freak out when I UT and reject the joint. When gouged out, I would find 1" - 1 1/2" long tunnels approximately 1/8" in diameter running under his last pass, parallel to the joint(horz & flat positions). It looked to me that the gasses were following his puddle along as he welded and just never made it up to the surface, maybe because of his fast travel speed and the puddle cooling before allowing the gasses to escape?
I welcome any thoughts, to put this to rest in my mind. I keep talking about it like I know what I'm speaking about, but I'm only guessing, and I would like to KNOW rather than guess.
John Wright