Welding galvanised steel tube / weldmesh?

Just weld it right through the zinc using wirefeed with innershield wire. If you haven't welded anything zinc-coated in the last few days, wear a fume respirator which will filter the zinc oxide fumes, or you may experience mild flu-like symptoms. If that happens, drink some milk (no kidding). After, spray the weld area with cold galvanizing solution.

Your other option is to rig up a trough filled with either acid (fast) or lye (slower) and let the solution eat off the zinc locally, then either get the parts re-dipped (expensive but long lasting) or spray with cold galvanizing solution after welding.

Grant

Just do like Grant said, respirator or drink a nice big glass of milk. Otherwise you'll feel sick.

rvb

-- As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17

"Grant Erwin" wroe: Just weld it right through the zinc using wirefeed with innershield wire.

^^^^^^^^^^^^^^^^^^^^^^^ Grant, please explain why it makes a difference whether you have welded galvanized material in the last few days.

The product of welding through zinc is zinc oxide, which isn't so much of a fume as a cob-webby white material that floats in the air, and settles or blows away. A fan will blow it away from you, but that may not be too good with gas shielding. Would be fine with flux-core. A paper mask, which won't handle fumes, is fine for this.

Zinc in your body is no big deal. Every multivitamin pill contains zinc. If you weld on galvanized steel every day you won't get "zinc fever". If you haven't done it for awhile, though, you will. That's why they used to call it "Monday fever".

Grant

Hello, Check this link,

What a bunch of baloney. Those guys might be great blacksmiths but what they entirely missed was that Paw Paw was an old man with emphysema who died of pneumonia. They of course are hysterically blaming it on zinc fever. He clearly survived the zinc fever, as he died weeks later.

Here is a sane and informed paper by the AWS on the subject:

OSHA name is weld fume fever.

Steve

Good link, thanks.

When I must weld galvanized material, I only do it outdoors or in a very well ventilated place. I try hard to only work at arms length and to keep my head out of the weld plume. I use a large fan if there is not a substantial breeze. When out side, I make sure that I am upwind and often also use the fan. I do wear a light respirator that fits under my welding face mask.

I find that chewing sunflower seeds helps to reduce the common metallic taste in my mouth.

I have read that research has found that welds made on galvanized material do benefit from increased corrosion resistance compared to plain steel, but also have had good luck using high zinc 'cold galvanizing' primer paint.

Be careful, YMMV

Thanks for the detailed replies everyone, I'll try at the weekend and let you know how I get on. Could you braze this stuff, with bronze rod and flux? Would the heat of the welding torch burn off the galvanizing? Thanks again, great group!

Use CAUTION and good ventilation and keep your head out of the fumes.

I suspect that torch brazing will cause more zinc to be burned than stick or MIG. Brazing will heat the steel red hot and this will burn the zinc. I suspect that you will be able to do each these welds much quicker with MIG and will heat and burn a lot less zinc. I suspect that the break where the square box section requires (re?) welding repair will be much stronger welded with full penetration all steel MIG due to the butt weld joint. Before welding with MIG, I would not bother to try to clean the weld locations (except the butt weld repair which may need some prep if it has an old broken weld), just work fast and don't allow too much heat buildup, weld part of the join and return after cooling if necessary. MIG works well using short bursts to limit heat buildup.

The real key to this type of repair is to try the easiest process first. If the MIG doesn't do the job then it will be easier to braze over the failed MIG than to try to MIG after brazing. YMMV There is no problem trying both and finishing with the process that works best. Use some high zinc (cold galvanizing) paint to finish the job.

Good luck, work safely.