I took your advice and went to Google to do a search on galvanized welding safety. After I read several articles, I did not find much doom and gloom other than an increased incidence/severity of metal fume fever as well as that those that had welded a lot of galvanized in the past avoid it or take additional precations to avoid the fumes to avoid the 'fever'.
It turns out that the white powder is Zinc Oxide and that the lead is reported to be less than 0.5% of the composition of galvanizing and thus avoiding the Zinc fumes also is effective in avoiding the Lead (and the Lead also oxidizes at a much higher temperature than Zinc).
Even though I will be outdoors and it is only about 10 minutes of welding, I think I will get a portable fan to blow the fumes away from me. Drinking the one or two liters of milk that some claim help treat the symptoms of metal fume fever is more than I wish to drink at a time. Another good suggestion I found was to grind the coating off the area to be welded to reduce the Zinc fumes--which I will also do.
The most interesting article was from Sperko Engineering titled "Welding Galvanized Steel -- Safely"
Dale in Tx
The article address is:
http://www.sperkoengineering.com/htm...Galvanized.pdf
Part of it is as follows:
"Welding of Galvanized Products
Welding of galvanized steel is done almost exactly the same way as welding of the bare steel of the same composition; the
same welding processes, volts, amps, travel speed, etc. can be used with little modification when the switch is made from
uncoated steel to galvanized steel -- unless the zinc coating is unusually thick.
The difference between welding galvanized steel and welding uncoated steel is a result of the low vaporization temperature of
the zinc coating. Zinc melts at about 900°F and vaporizes at about 1650°F. Since steel melts at approximately 2,750°F and
the welding arc temperature is 15,000 to 20,000°F, the zinc that is near the weld does not stand a chance -- it's vaporized!
By the time the weld pool freezes, the zinc is gone. This has two immediate consequences:
• The vaporized zinc increases the volume of welding smoke and fumes.
• The zinc at and near any welds is actually burned off by the heat of the arc, removing the protective zinc coating.
Zinc Fumes -- A Safety Hazard?
When zinc vapor mixes with the oxygen in the air, it reacts instantly to become zinc oxide. This is the same white powder
that you see on some noses at the beach and the slopes. Zinc oxide is non-toxic and non carcinogenic. Extensive research1
into the effects of zinc oxide fumes has been done, and although breathing those fumes will cause welders to think that they
have the flu in a bad way, there are no long-term health effects. Zinc oxide that is inhaled is simply absorbed and eliminated
by the body without complications or chronic effects. Current research2 on zinc oxide fumes is concentrated in establishing
the mechanism by which zinc oxide causes "metal fume fever," how its effects are self-limiting and why zinc oxide fume
effects ameliorate after the first day of exposure even though the welder may continue to be exposed to zinc during subsequent
days ("Monday-morning fever"). Other research3 is being done using zinc oxide fumes together with various drugs which
results in a synergetic effect for treatment of cancer and AIDS. Another area of research is use of zinc compounds as the active
ingredients in throat lozengers that are recognized as significantly effective in reducing the duration and intensity of the
common cold.
Typical “metal fume fever” begins about 4 hours after exposure, and full recovery occurs within 48 hours. The symptoms
include fever, chills, thirst, headache and nausea. All of these symptoms, pain and suffering, as well as lost work (and play)
time, can be avoided entirely by simply not inhaling the zinc oxide fumes. This can easily be done using any of the
methods described later."
