>Hi Folks,
>
>Anybody aware of the safety recommendations for MIG welding galvanized
>metals safely? I'm plann to finish up the replacement footwells in a
>Series III over the weekend and don't want to inhale any bad stuff!
Grind away the coating from the area to be welded. If you don't, it
will get vaporized anyway, so the protection will be lost. That
avoids the potential health problems. If you don't grind it off, you
need to use somewhat higher heat and slower travel, to allow a weld
puddle that is molten for long enough to allow the zinc to bubble
out. You also need to use a heavily deoxidized wire.
You could also use a silicon bronze welding wire with 100% Argon
shielding gas. This requires less surface prep, as the silicon
bronze filler has good affinity for the zinc, resulting in much less
loss to evaporation. Silicon bronze also has greater corrosion
resistance than steel fillers, so it's not always necessary to repair
the damaged galvanized surface. That's probably a moot point, since
you're likely going to be painting the footwells, but it's a big win
for things like HVAC use -- And galvanized chassises, too. You still
don't want to breath the fumes, but good ventilation should be
enough without needing a positive pressure system.
I recently welded some panels into one of my galvanized footwells --
covering the holes for the pedals to pass through and filling
various bolt holes and the like, so I could cut a different set of
holes for a new heater. I merely ground the zinc away from the
edges to be welded, and welded with mild steel wire, then painted.
Were I doing modification to a galv'd chassis, I think I would go to
the trouble of getting a 100% argon bottle and silicon bronze wire.
David
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