[TowerTalk] Tack welding rebar, need howto

[Jim Lux]

On 1/3/14 6:13 AM, Patrick Greenlee wrote:
>
> As regards having the wind or a fan at your back to avoid breathing the
> fumes. Not a good idea. Not a sound idea aerodynamically speaking. Wind
> in your face is not the best either. Take a look at the videos on YOU
> TUBE showing welding. Huge plumes of fumes are generated.  Wind at your
> back generates eddies and vortices on your lee side (face and chest
> side) and puts you in the position of breathing in significant
> quantities of fumes. It is far better to have the wind or fan produced
> breeze blowing sideways left to right or right to left to clear the
> fumes. Having the breeze come from several degrees to the rear but I
> wouldn't exceed about 15 degrees.  The idea is to have the fumes blown
> away and not recirculated around your head.

As a practical matter, a fan over your shoulder works. Or having the 
wind over your shoulder.

I think the general idea is "position yourself so you don't breath the 
fumes".. Fortunately, they are quite obvious.. it's not some stealthy 
invisible gas.

>
> Zinc poisoning is not a casual minor thing to be ignored.  If you do
> breathe some zinc fumes one of the symptoms may be a metallic taste I
> your mouth. The non-ferrous foundry workers casting zinc and welders
> welding galvanized material that I have observed always drank
> significant quantities of milk as a partial cure.  I did some Google
> searches and saw where milk was recommended too. I am not a medical
> doctor and am not advocating a medical procedure, just reporting what I
> have observed.  YMMV

It sure isn't something to be ignored.. BUT, if you're talking about 
someone tack welding half a dozen bolts to some rebar, the amount of 
zinc involved is pretty small. And given the speed at which most hacker 
welders work, there's going to be some time lag in between the welds to 
allow the smoke to clear, if only because the time required to walk 
around to the other side of the rebar cage or whatever.



>
> I frequently weld galvanized steel. It has been decades since I had
> "that metallic taste" in my mouth from it. I do take precautions to
> avoid breathing the fumes.

yeah.. I have an acquaintance who does a fair amount of welding on 
galvanized sheet metal ("corrugated metal roof" and "water tank" kinds 
of applications).. His approach to these things is decidedly less 
casual, but then, he's doing it every week, and for long periods, and in 
close spaces.  He has a bunch of ventilator fans with flexible ducts on 
them.



   P.S.  auto-darkening hoods ROCK!!!

Truly.. Better living through technology for sure.


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