galvanise dipping

johnpawl

I was told not to use a normal stick welder when welding something that is to be galvanise dipped because if the weld isnt perfect the slag that cant be chipped off reacts with the galvanise..so I welded up a gate with a gasless mig, and I'm just ater hearing that the flux on this produces slag like a stick welder... Am I in trouble???

slimjimmc

I'v got little knowledge of galvanising but according to this article the problem with slag appears not a chemical reaction but simply that zinc won't stick to it. On that basis I doubt there should be any problem if you clean up the welds, perhaps give them a good rub with a wire buffer or grinding wheel.

Spannerman7

Chip off the slag and give the weld a rub of a wire brush, someone has misslead you, there are many situations where a stick rod is required as Mig is generally just one grade of steel, rods gives endless choice. If the slag is left on the galv wont get under it and it will rust and the slag will fall off after time. I weld every day almost, Mig,MMA (stick), Tig for Alu and stainless.

johnpawl

Spannerman7 wrote: »

Chip off the slag and give the weld a rub of a wire brush, someone has misslead you, there are many situations where a stick rod is required as Mig is generally just one grade of steel, rods gives endless choice. If the slag is left on the galv wont get under it and it will rust and the slag will fall off after time. I weld every day almost, Mig,MMA (stick), Tig for Alu and stainless.

My welding isn't great, I can manage on flat plates and corners but its welding around the 16mm round bars (on a gate) that my weld sometimes has holes in it...He reckons that as I cant chip the slag off the welds in the holes that here is where I'll have problems...he was saying something about black stuff weeping out ot the holes in the weld after it has been galvanised, what you think of this? Thanks..

Spannerman7

You need to remove the slag, you should not be burning through and need to change your method. One of the best welding sites is weldingtipsandtricks.com there could be a number of things wrong with the method you are using, amps a bit too high, feed too slow, stalling in the one place, torch angle. Spend some time on that website and/or find someone to show you. There is no problem galvanizing parts welded with stick/gasless mig when the slag is removed. If you were down this way you'd be very welcome, there must be someone local you can ask.
Spannerman