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Thread: Welding galvanized steel

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    Welding galvanized steel

    I bought a carport with galvanized steel tubing that is around 11 gauge. I want to weld the tubing. It has an insert to connect the two pieces of square tubing together using screws but I want to weld it to make it stronger and to reduce the number of anchors I would need. The weld will be a butt weld and the insert can act as a backing plate. I do not know what process to use. Stick will probably burn through. Should I MIG or flux core? I will use a lincoln 140. Should I grind off the galvanized metal? If so, how far back? What respirator filter should I use? Can I use flux core with a fan and stay upwind without a respirator?


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    Re: Welding galvanized steel

    You will need to do a lot more prep of removing the galvy if you mig weld it. usually just a PIA.

    I would get some Fluxcore and weld it up.

    http://www.sperkoengineering.com/htm...Galvanized.pdf
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    Re: Welding galvanized steel

    Fumes from welding galvanized metal are highly toxic. As I recall the correct respirator filter is the purple one.

    The only process that I'm aware of that does not require you to remove the galvanized coating first is to use silicon bronze MIG wire. Otherwise you need to grind off the galvanized coating (and still wear a respirator).
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    Re: Welding galvanized steel

    Quote Originally Posted by scsmith42 View Post
    Fumes from welding galvanized metal are highly toxic. As I recall the correct respirator filter is the purple one.

    The only process that I'm aware of that does not require you to remove the galvanized coating first is to use silicon bronze MIG wire. Otherwise you need to grind off the galvanized coating (and still wear a respirator).
    the PDF link I posted has the respirators and filter recommendations as well as the info for galvy welding.
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    Re: Welding galvanized steel

    You could use stick to weld it, 11 gauge is almost 1/8th so its not like we're talking autobody thickness, some 3/32 7018 or 7016 would do the job.

    If you do use MIG i'd be going for self shield flux core, it's become my new favourite process for welding pained, galvanised and rusty steel, some .035 E71T-11 (NR211mp or equivalent) would do the trick nicely I think.

    If you do weld it, wear a respirator for sure, zinc poisoning is no joke, it's carcinogenic which is bad enough, but it will also make you incredibly sick short term as well.

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    Re: Welding galvanized steel

    Quote Originally Posted by scsmith42 View Post
    Fumes from welding galvanized metal are highly toxic. As I recall the correct respirator filter is the purple one.

    The only process that I'm aware of that does not require you to remove the galvanized coating first is to use silicon bronze MIG wire. Otherwise you need to grind off the galvanized coating (and still wear a respirator).
    I like using silicon bronze on galvanized because it burns off less of the zinc coating, especially on heavier stuff like strut, and angle. I still give it a shot of galvanizing spray. Doesn't seem to rust up a quickly either. Since this is just for support, it might be a good place to use it. All you need is a spool of SiBr, and a bottle of argon, and a mig machine. It even works on clean rusty steel/ sheet metal, and auto exhaust components where its easy to burn through with fluxcore, stick, or mig . The wire isn't cheap though , but great at what it does.

    It just seems anytime I use fluxcore it rusts faster than anything else.(like before I can get paint on it https://www.weldingweb.com/images/smilies/laughing.gif

    Good luck !
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    Re: Welding galvanized steel

    If you are gonna stick weld, use 6010. That'll burn through it but smoke like hell. You'll have white flaking too.
    Never ever considered 7018. No idea what it would do.


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    Re: Welding galvanized steel

    Question---Why not just drill a hole through insert, upper and lower pieces and use through bolts? Stronger than screws and you can disassemble it when it flies off or collapses.

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    Re: Welding galvanized steel

    I would just stick weld it with 6010 and stay upwind or hold my breath momentarily when immersed in fumes. Zinc isn't THAT toxic, not like it's cadmium or something...

    Yeah, I heard about the guy who died from it, but he was cooking something like 16 tons of galvanized sh!t in a ceramics kiln or something stupid like that, and he probably inhaled 40 pounds of zinc...not recommended.
    Last edited by Kelvin; 09-28-2021 at 07:28 PM.

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    Re: Welding galvanized steel

    Your looking for a more secure bond, just 6010 that sucker on 1 side and be done. Your not doing a structural weld.

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    Re: Welding galvanized steel

    around the turn of the mellinium, was the tabbacco settlements/payouts, and the public schools in my area were putting up fences/roll gates galore. so i welded alot of galv., which got powder coated. so, i'd do it outside upwind or fan like u say , and .035 nr211. it couldnt hurt to wire wheel it while drinking a milk befroe. if u gettin a purpleish radical puddle, then gotta go to plan b , but the galv usually aint that thick on the stuff ur talkin
    Last edited by 123weld; 09-28-2021 at 08:26 PM.

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    Re: Welding galvanized steel

    Remember the garage is engineered (and probably any warranty) based on using screws. Welding could weaken the tube or make the structure too stiff for wind load. Grinding off galvanize could cause rusting. If you are asking about how to weld it, there is a chance you may burn through and create holes.

    I would think a long time before welding. Not everything is better by welding.
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    Re: Welding galvanized steel

    Quote Originally Posted by wb4rt View Post
    Remember the garage is engineered (and probably any warranty) based on using screws. Welding could weaken the tube or make the structure too stiff for wind load. Grinding off galvanize could cause rusting. If you are asking about how to weld it, there is a chance you may burn through and create holes.

    I would think a long time before welding. Not everything is better by welding.
    AND,, if it is a tube in a tube,, it is a BIG lap joint,,
    Do you want it stronger,, ?? Then use JB Weld,, Heck,, I would bet if you assemble it with Gorilla Construction Adhesive (in the caulking gun tube) you could never get it apart,,

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    Re: Welding galvanized steel




    I sent some pics to show what I have. The base rails were supposed to be 30 feet long, but my trailer is 16 feet long. So I transported 3 twenty foot sections and cut one in 1/2 and was instructed to screw it together using a 12 inch insert ( tube within a tube). I was also told to place mobile home anchors. One on either end of the 10 foot sections and three for each 20 foot section. If I had a continuous 30 foot section, I would only require 3 anchors per base rail instead of five. My desire to weld is to get the strength back to the original design and reduce the number of anchors needed. My ground is extremely hard sandy clay and each anchor is a real chore.
    I was thinking the smaller inner tube would act like a backing plate and keep me from burning through and make the welds strong.
    Even with a backing plate, I am reluctant to use 6010/6011 stick because I would cause it to burn through. I was told by the worker that welds these all the time to avoid stick for that reason. I do not have enough stick experience to trust myself on this type of weld. I could just grind all the zinc off and MIG weld it or flux core without removing the zinc. I am not convinced that construction adhesive would be strong enough to reduce the number of anchors, like i want to do.
    So I am down to choosing between grinding away zinc and MIG welding or using flux core with or without grinding.


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    Re: Welding galvanized steel

    wait, is that Zinc Plated ?


    You mentioned galvanized in the op.
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    Re: Welding galvanized steel

    Quote Originally Posted by Broccoli1 View Post
    wait, is that Zinc Plated ?


    You mentioned galvanized in the op.
    It is not zinc plated. It might look shiny in the pics, but that is the flash on my camera. It is a dull gray finish and was hot dipped.


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    Re: Welding galvanized steel

    Kize had it right earlier. Just through bolt it or use a number of self tapping screws on each of the sides of the tube.
    Why do you think need extra anchors if it is not welded?
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    Re: Welding galvanized steel

    Quote Originally Posted by psacustomcreations View Post
    Kize had it right earlier. Just through bolt it or use a number of self tapping screws on each of the sides of the tube.
    Why do you think need extra anchors if it is not welded?
    That is what the man told me when I asked why I had so many anchors.


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    Re: Welding galvanized steel

    It is better to grind of the gal.
    Some welders would use E6011
    I use a flux core no gas E71T-11 or E71T-G 0.030 [0.8mm].

    I would weld outside using N95 mask 😷.

    Other on this thread has said about same.

    Dave

    Quote Originally Posted by jeffrey.penfield View Post
    I bought a carport with galvanized steel tubing that is around 11 gauge. I want to weld the tubing. It has an insert to connect the two pieces of square tubing together using screws but I want to weld it to make it stronger and to reduce the number of anchors I would need. The weld will be a butt weld and the insert can act as a backing plate. I do not know what process to use. Stick will probably burn through. Should I MIG or flux core? I will use a lincoln 140. Should I grind off the galvanized metal? If so, how far back? What respirator filter should I use? Can I use flux core with a fan and stay upwind without a respirator?


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    Re: Welding galvanized steel

    Just another day in the office. 12 ga 8" od pipe butt weld onto a schedule 40 cone. No grinding the hot dip off, 1/8" 6011C at 85 amps. First pass went in just fine, the second came out a little more convex than I wanted. Name:  20210929_095310.jpg
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    Re: Welding galvanized steel

    I built a large gantry crane out of hot dipped A36. Very thick galvanized coating. Gummed up a grinding wheel like aluminum. Anyway, for welding galvi., get the zinc off with a hard stone or a flap wheel, then weld as usual. Run a fan for ventilation and stay up wind of the fumes. The biggest (non-health related) concern I have with welding galvanized is that it makes the welds freeze slower - "runny". Plus it makes an absolute mess on your welding hood. I keep a rag with me to clean the lens every few welds. If you can help it, hold your breath during the weld, flip your hood up, step back, THEN take a breath.

    I should say that most of the galvanized I weld is extremely thick. Not like galvanized pipe. Thick like powder coating.

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    Last edited by 52 Ford; 09-29-2021 at 10:55 PM.

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    Re: Welding galvanized steel

    Quote Originally Posted by jeffrey.penfield View Post

    I am not convinced that construction adhesive would be strong enough to reduce the number of anchors, like i want to do.
    According to the Gorilla website, your 6" lap of a tube in a tube would require 168,000 pounds to cause failure,,
    Allow 5 to 1 safety factor for failure to clean, and not apply the adhesive completely, it would still take over 30,000 pounds to pull the joint apart,,

    Try that with the weld, the weld will fail at 10,000 pounds,, or less.
    Sometimes it is hard to believe "glue" can be better than weld,, HUH??

    "Glue" held the Space Shuttle together,,

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    Re: Welding galvanized steel

    Quote Originally Posted by jeffrey.penfield View Post
    I am not convinced that construction adhesive would be strong enough
    You planning to try to anchor down Atlas rocket boosters ... or just a few Chinook helicopters in an F5 tornado?
    Last edited by Kelvin; 09-30-2021 at 12:31 AM.

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    Re: Welding galvanized steel

    Honestly, if it was me, I'd just screw it together. If I was worried about the screws pulling out, I'd add a strap to the sides of the joint to tie it together. Prolly just use some #12 or #10 screws and some sheet metal.

    Otherwise, refer to my last post. I hope my advise there will help a little.

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    Re: Welding galvanized steel

    I have not considered adhesive on this welders forum before, but you make good points. I understand that the adhesive could be much stronger at resisting separation of the tubing ifI tried pulling them apart. But what about left to right movement? For my case it would be plenty strong, but for general knowledge, wouldn’t a butt weld be stronger at resisting lateral movements than adhesive on an insert?
    I might consider adhesive some other time, but I am going with welding on this one. I am a hobby welder and any weld is good practice and good fun. Gluing pipe, not so much.
    I am retracting my earlier concerns about stick welding it. I have some 3/32 e6011 and an excellent stick welder (Linde 305). I wont have to separate the tubing and grind anything. I can just weld away. I will wear an 95 mask, hold my breath, weld outside with a fan and see how it goes. I will tack weld the corners to make sure I do not burn through before welding the ends. The insert will be a nice backing plate and the screws I placed earlier will hold it in place. This will be done in 1-2 days and I will update you if all goes well.


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