flux core, downhill?...

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so im taking a break from the world of structural, and im working in these pretty laid back shop, not near as much money, but close to home and lots and lots of hours.Anyways, were installing a staircase, 2.5X12 c channel stringers, and custom broke stair pans.  Today we were fitting everything and just tacking it in and im gonna head out tomorrow and weld the rest of it all the way up. Heres my questions, i believe were using e71t-gs 0.35 on a millermatic 172-175 about maxed out.  Im used to corshield 8, 211 and 232, in the bigger sizes(.045-.072) all of which the slag will leave a nice smooth coating over the entire bead, but when i use this wire i only get slag coverage along the toes.   What gives?  When im running it, i have a nice smooth even slag line, but when the hood comes up, id say its only about 50% slag coverage.Second question has anyone run this stuff downhill, succesfully?  Bossman told me to run it downhill because it wont get as hot and it will leave a nice smooth weld.  I dont run anything downhill thats not the way i was taught.  Obviously the welds will be colder, but i tryed a few and the slag doesnt seem to be getting ahead of the puddle.  The pans are 16 gauge i believe and the stingers are something like 1/4" in the web, stringers welded into the stair pans (favoring stringers so i dont burn through) Most weld joint have slight gap 1/16-1/8.Everything is galvanized.  I have my suspicions on theories about each, just curious what others think...
Reply:It can be done downhill, but you will have to travel faster and have a lesser deposition rate.  You may also have problems with concave welds.  I'm not saying that it can't be done, or that it isn't good in your situation.  You may even find that it's so much easier downhill that you can two pass it to keep from being concave, and wind up with a nice looking weld when you're done.
Reply:Years ago, when Lincoln first released NR 211MP it was rated the same downhill as it was up. I skinned many a dozer face with a root washed downhand......
Reply:I run fluxcore both up and down, depending on the thickness of the steel. If it is over 1/4", I almost always run up. 1/8" I usually run downhill.You can run a bit faster, and for sure, the welds look cleaner.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:i have no problem making fluxcore up look good, and i dont have a problem running it down, in this circumstance.Im curious though as to why there is not full slag coverage?
Reply:I have never run anybody's GS wire,,,,,  but ......Lack of slag coverage on an -11 wire is usually due to too high voltage,,,,  or the wrong amount of stickout ...
Reply:im using about a 3/8 stickout, im pretty sure the wire is being pushed a little further than it should be.  Ill try and snap some pics today
Reply:0.035 FCAW downhill for 16 ga sounds OK.  But that is probably going to be on the cold side for the tie-in to the 1/4 inch.btw, NR-211MP is rated all-position, with the caveat that the 3/32 wire is not recommended for out-of-position welds.  Also a reminder that NR-211MP (and other AWS E71T-11 wires) is NOT rated for any work requiring CVN impact properties, like structural work or bridges or pressure vessels or seismic-zone work.  And the SF Bay area sure is a seismic zone!  And a steel stairway sure sounds like structural work.211MP in 0.035 size tops out at about 120A at 16.5V and 110ipm.Yes, you aren't running 211MP in this case.  But I'd double-check the building code requirements for weld requirements to make sure the -GS wire is rated for the code requirements.  Or have someone else in the shop/company double-check it.  Or the architect or engineer double-check it.I'd guess that you are running the volts and amps a bit past where that wire in that size are supposed to be run.  Which probably means you are burning off the slag before it can totally turn into slag on the weld bead.And to me, a 1/8 gap with 16 gauge sheet metal is NOT a slight gap.  Sheet metal IMO should be tight together so that the weld can join the sheet right away without the welder having to dance the puddle from the one side across to the other and fill in the air gap while not melting the sheet.  Yes it can be done but it takes the welder longer and makes for more weld having to be done.  And time=money.
Reply:Sometimes downhill can be your best friend in that type of work. I routinely run 10 class electrodes downhill (standard practice in oilfield piping). I run flux core (if it's rated for it) downhill on the light stuff, and uphill on anything heavier than 10ga. I've repaired a bunch of roll off cans in the last couple of years using NR211-MP. All warranted for 1 year. These things take a beating (haul cast iron, aluminum and steel scrap) and I haven't had a single weld failure. Well there were those on this one piece of angle they hung with a crane and ripped the 3/16 X 3 X 2 angle in two. The welds ripped out, but none of them broke. I don't think there is a code on these things. Otherwise none of them would make it out the factory door. Crappiest welding I have seen outside of a boat yard. Nothing against boat builders and I am sure some are excellent welders. I just haven't found any of them down here.I did a little digging and the self shielded flux cores I found rated for seismic codes are going to be extremely difficult to use on ornamental iron work and stairs. Very little of that stuff is built of material heavy enough to handle them. Maybe they are heavier in CA than they are here. I've done a lot of repair work on stairs and railings at apartment complexes using NR211-MP and none of them have failed to pass inspection for any reason. The IBC version we are under here doesn't specify an AWS classification for electrodes used on stairs and hand rails. No seismic concerns just a minimum wind load of 140mph.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Whose wire is it?  We used to have similar problems in any position using Lincoln flux core wire.  Switched to ESAB, no more issues.
Reply:i exaggerasted, the gaps are at not very big, ran most of my vertical stuff going up, some of it i did going down.211MP in 0.035 size tops out at about 120A at 16.5V and 110ipm.i believe there lies the problem, although today i adjusted the welder and got it running better. And to me, a 1/8 gap with 16 gauge sheet metal is NOT a slight gap. Sheet metal IMO should be tight together so that the weld can join the sheet right away without the welder having to dance the puddle from the one side across to the other and fill in the air gap while not melting the sheet. Yes it can be done but it takes the welder longer and makes for more weld having to be done. And time=money.I have no problem filling the gapsanyways my original hunch was that the wire is running too hot for itself and burning the slag, which is what i believe was happening.Ill try and get some pictures of the staircase tomorrow, every picture i take with that peice of junk comes out crooked though
Reply:With handrails all you are really doing is tying one rail into the other. The rail is welded on the stringer already so a downhand pass works fine. You put FAR less heat into the rail AND you have way less grinding to do.'Mike
Reply:It is not recommended to weld down hill with flux core. i was taught against it due to cracked welds because of excessive travel speed. Read the report at the American Welding Society. Welding down hill of boat hulls was specifically mentioned. The number of degrees down hill is the main factor when talking about down hill, which no one has talked about.Yes there is some crappy welding at boat yards, But i have seen some of the best welding at boat yards too. i have seen bad welding avery where.There is special wire for welding galvinezed metal, You should have your boss look into it.Many stores all have the same wire. Whatever sells the fastest. That does not mean it is the best choice for the job.AWS certified welding inspectorAWS certified welder
Reply:Donald, that wire for the galvanize is E71T-GS. The same stuff he is using. For anyone wondering I have never used it, but my dad has. LWS recommended it to him back when it was brand new stuff. He says it works better on galvanize better than anything he has ever used and works just as good when there is no galv.As far as the downhill with flux core goes. These cans I worked over are built out of 10 and 12 guage and some of the patches are 14 and 16. Not much meat there for holding uphill heat. These things are seriously abused. Loaded to 40,000+ lbs and then loaded using a forklift. They pick one end up by one corner (twists them bad) back the trailer under it and then go around to the back and pick it up and push it on the trailer. I've had them flip them up on their sides and upside down so I can work on the bottoms. None of those welds made with NR211-MP have failed yet. It's tough stuff.The difference between art and craft is the quality of the workmanship. I am an artist.