Welding gal coated metals

[Mick B]

This afternoon I was trying to mig weld some 16mm gal nuts to some 8mm mild steel.. I cleaned up both the steel and the nuts with a flap disc to get rid of the gal (off the nuts). When I welded them together I was amazed at the amount of splatter. Is this splatter normal when welding anything with gal on it ?
There was lots of that white fluffy powder around too which I think is normal when welding gal. I tried adjusting the wire speed down and the volts down to stop the splatter and when I finally got a decent looking weld the setting were no where near what I would have thought they should have been for my machine.

 

[cumbriasteve]

Yes very normal, even cleaning it off does not always get rid of it all.

Very dangerous stuff to be breathing in.

 

[Wendelspanswick]

It's an easy mistake to make, you sand off the dull zinc and see bright metal underneath so you stop, the trouble is the bright metal underneath is quite often just the fresh, untarnished zinc, you need to remove a fair thickness to get to clean metal and a grinding disc is more effective in my opinion.

 

[gordon stephenson]

Also, if the metal is pitted with rust before galvanising. The zinc penetrates the pits and boils off causing the spatter that you mention.

 

[pedrobedro]

Splatter is what cows do on wet concrete Nuts are thinner on the walls than you think and the passivated zinc is also inside on the threaded part so it furs up when the heat gets to it. The amount you will be exposed to welding a few nuts is negligible

 

[500e]

Don't know if it really helped but a couple of welders I new used to say if welding any Zinc coated material to drink a pint of full milk as it helped cut down the chance of fumes screwing you

 

[cumbriasteve]

Save yourself a trip to the supermarket.

From the EH&S guidance for welding galvanised material:

Metal fume fever
Many welders report flu like symptoms after welding. The effects are often worse at the start of the working week. Metal fume fever is usually linked to welding or hot work on galvanised metals. High exposures to mild steel weld fume can also cause this illness. Metal fume fever does not usually have any lasting ill effects. Don’t believe the stories about drinking milk before welding. It does not prevent you getting metal fume fever

 

[pedrobedro]

High exposures to mild steel weld fume can also cause this illness. Metal fume fever does not usually have any lasting ill effects.

This is the relevant bit for me. We used to cut and weld galvanised ducting in the foundry and with no special precautions apart from good ventilation and none of us ever suffered any ill effects in 2 years I worked there. Where do all the horror stories and panic mongering come from ? The old welders probably drank their pint of milk and never had any problems so attributed it to that, at least the milk was doing them no harm.

 

[fixerupper]

Yep I spent three years in the 70s at Woods of Colchester owned by GEC working in the Duct shop doing Guiliotine opp , flame cutting ,grinding , fettleing loads of the stuff we worked on had been galvanised ... the welders worked on galvanised stuff, I never herd anyone complaning ....jeff...

 

[Chris Stevens]

Zinc is burning out of the nut threads. Unless you have a tap to clean as much zinc out the threads as possible, you will have to put up with spatter and rather nasty fumes. Best to get some uplated nuts.

 

[Kent]

Zinc fumes can have long term effects I used to work with a victim of this