18 gauge to 3/8" angle 4F ?

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I have to weld some 3*3*3/8" up to the 18 gauge corrugated galvanized sheeting that holds up the poured concreet slab. The slab Is poured. I'm thinking of NR211 0.030" flux cored. There is a bunch of this to do so I'd like to get something that worked first timemig is another posability. But I don't think it will like the galv so much. The angle is "supposed" to be structural. Engineers pipe dream I say. But then who am I ?Any one done this?Suggestions ?G
Reply:lemme get this straight you're trying to weld 18 ga (0.050  to 3/8  0.375)  plus its galvanized?   can you shows us a picture or a sketch of the piece so i can get idea of the geometry?and what type of load is this carrying because 18 ga is barely ever considered structural?  We used to weld up 18 ga stainless steel, to 1" plate steel, but it was more as a vapor barrier than a structural weld. Ideally you should grind off the galvanizing, it's not kosher to weld through it both from the metallurgy standpoint and for the health factor.  I would pick mig as it has less penetrating power, flux core will want to burn right through the 18ga.  Preheat the 3/8 channel to 300-400 deg or else you will get a lot of cold lapping on the thicker material.  Besides that the weld should be easy if not a little goofy.  The big thing is preheating the thicker material because it will act like a heat sink and blow through the 18ga all day.Welding EngineerCertified Scrap Producer
Reply:Nah, the 18 gauge isn't the structural part.  The 3/8 angle iron is the supposed structural part.But the 18 gauge is supposed to be the 'pan' that holds up a poured in place concrete slab?And structural and NR211 don't really go together in my book.  NR211 has its place and uses, but structural isn't one of them.  Especially seismic structural work.  Lincoln says NR203-MP or NR232 or NR233 among a few others for Innershield (FCAW-S) seismic structural work.Also note the workpiece thickness limitations of NR211 right from Lincoln of 5/16 inch MAX for 0.045 and smaller wire.  To me, using it on some 3/8 thick angle iron is kind of dancing around that thickness limit even though the other piece is only 18 gauge.And then you have the corrugations to deal with.  Just how big and how 'structural' are you talking about here?  3x3 angle iron with an 18 gauge pan doesn't sound all that big to me for 'structural'.  Sounds more like some steps maybe?Structural and engineer and steel and concrete says to me that the engineer on the project should figure out what and how it is supposed to go together.  Including D1.1 compliance and the WPS among other things.Hmmm, I knew I saw something similar to what you are asking about somewhere in the Lincoln literature.  Finally found it in the SMAW Guide.  For 18 gauge roof decking doing a burn-through spot weld onto the top flange of a beam (about as close as I can find to your stated scenario), Lincoln says a 1/8 inch E6022 (Jetweld 22) electrode at 150 amps.  Note: no CVN properties for E6022 electrodes.  If CVN properties required based on structural/seismic codes, that filler would not be appropriate.Maybe DDA (?) the concrete guy down in Texas will chime in.  I have a faint recollection of him/others chimimg in here or on another forum(s) about something similar and one trick was to tape the stinger handle to a broomstick to allow the welder to stand upright and not be hunched over all day long.  That and don't step on the still hot welds with the shoes.    IIRC, you have to make sure the decking is tight against the flange, then you burn through the sheet and then fill in and finish with a little swirl-around.Last edited by MoonRise; 05-14-2010 at 02:30 PM.  The best laid schemes ... Gang oft agley ...
Reply:NR232 and 233 and other T-8 class siezmic structual wires are not available in a thin enough wire size to be at all useful for welding anything 18 ga.   Minimum thickness on these wires is usually 1/16.  The 18 ga won't stand a chance with that thick wire.What is used for this application is a thin (.030 or .035) T-GS or T-11 fluxcore self shield wire.  The fluxcore welds fine through the galvi 18 ga and the primerd I-beams without grinding.  This is a California seizmic zone acceptable method of welding light gauge galvanized metal to structural beams.You will need to keep the heat directed on the thick beam and wait for the puddle, then wash it over to the sheet gauge metal and keep working the puddle that way along the joint.   You will have to dial the machine up high enough to allow fusion with the beam metal but not so high that you blow through the gauge metal.  It's a balancing act that only experience will teach you.  My friend and I used our Passport migs with .035 Hobart Speedshield GS (E71T-GS) self shield fluxcore wire to weld all of the metal stud framing, kickers, tracks, caps and clips to the heavy c-channel and i-beams on several school buildings here in southern California.   Fluxcore without grinding is the most efficient way to do this.  It can also be done with 6011 stick, but stick is slow and fluxcore makes more sense when there are so many welds to complete on a project as big as several school buildings at once.  The crew putting up the roof decking did use 6011 to plug weld the deck to the beams though.Gas mig would be a disaster in this application, as that would require griding which takes way too much time and even though you grind one side, the galvi is still there on the other side comming through into the weld.  The result is porosity.  The flux in the fluxcore wire protects the weld from the galvi contamination.  Gas mig would also be a pain due to the wind blowing the gas away, since construction like this is done outdoors.Last edited by DesertRider33; 05-14-2010 at 03:19 PM.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:4" concreet slab on 18 ga corrugated sheet. Engineer says that where the subs cored through the slab ( when the cores  are several together)I need to put the angle to twelve inches past the end cores on both sides of the row of holes" tacked " up to the sheeting. The lengths of angle is supposed to support the slab where the holes have compramised it. I don't see it and just called the contractor and suggested that we bolt them up at the ends as welding wasn't ideal.G
Reply:if you cut an opening in a reinforced slab you are supposed to frame the opening  with suitably sized members(the 3x3x3/8 angle) welded back into adjacent  structural beams,( which support the opened decking and slab,) not welded to the decking. this engineer is 100% wrong. sometimes the engineer is thinking ahead and requires the rebar to "diamond"  around the area where the cores are goingto go, making the framing of the slab unnecessary. but not this engineer.
Reply:with you on that Weldbead.Yes the engineer wants to bolt them up now (expansion bolts every 12")i could see the point of welding if they were going from i beam to Ibeam, but not the way they drew it.just got word back that there is 240' of 3x3x3/8" angle to go up in total....lots of holes!G
Reply:i always preferred to set sleeves on the deck. that way the rebar can work around them, no coreboring,no framing. sounds like the sub made swiss cheese(plumbing stacks??)