Welding Galvanized Steel

[pepster]

There have been some questions on another thread regarding the welding of galvanized metals and the safety concerns caused by this. I have chosen to start a new thread because I believe this information is important and because the "Monkey business" occurring on the other thread may have discouraged many of you more serious minded readers from reading those posts.

The problem with welding galvanized steel comes from the zinc coating. Zinc melts at around 788 degrees Fahrenheit and boils at 1665 degrees Fahrenheit. Because the temperatures required to weld most steels can exceed 2500 degrees, the zinc coating will be vaporized and can therefore be inhaled.

Exposure to the zinc fumes can produce "Metal fume fever". This is also known as zinc fever or "Brass Founders Ague" the symptoms can be quite serious but are usually non fatal. The symptoms consist of irritation of the throat, malaria-like chills and other fever related symptoms such as headache, nausea, lassitude, joint pains, muscle cramps, dryness of the throat, constricting sensations in the lungs, dry cough, tachycardia (rapid heart rate), elevated blood pressure, fever and sweating. While these symptoms are frequently misdiagnosed as pneumonia or the flu, recovery is usually rapid. The symptoms rarely last more than 12 to 24 hours.

With this knowledge, I think most of you would agree that it is best to avoid exposure to zinc fumes. If you must weld galvanized steel, either grind away the zinc coating where the welding will occur , weld outside and stay upwind or use an appropriate respirator.

A happy and healthy holiday season to all.
Pepster

[Jerry]

I used to work for a shop where we welded a lot of this. We welded 16 & 14 gage ductwork and when we asked for some issues to be addressed they bought us a couple of small $9.99 fans to blow it away, you guessed it right towards someone else. But when the building filled with white smoke we'd open a door.(what a ventilation system we had there)

I even was tested once by an outside source who clipped a test thing on my shirt and later all I heard was we were within an okay limit.
Old guys at work said drink milk, well whatever, I agree that it is very dangerous and that the ventilation or exhaust should be very good as to prevent exposure.

[Double D]

Pepster,
You are so RIGHT! The only way I will weld anything with gal. coating is to weld with a respirator for that purpose. Just as a note: to agree with Jerry don't just drink milk. Maybe someone sould purpose that one to myth busters.

Safety First
Double D

[Franz]

Pepster have you ever hauled a man into the Emergency Department because of galvanize or zink fume inhalation? I have, and I assure you while your scenario might be correct in minor cases, zink fumes can KILL rapidly in sufficient quantity.

Zink fume inhalation and the treatment thereof because you believe you only sucked in enough to make you feel bad isn't something to play with. The line between you're gonna feel like crap, and congratulations you won the dirt nap is blurry, and the decision shouldn't be made by someone under the effect of ZINK POISONING.

The reality is if the doctor at the emergency room doesn't know what the difference between ZINK POISONING and Metal Fume Fever or make the proper diagnosis, you will leave the hospital in the back of the local mortician's pickup car. ZINK POISONING will cause a rapid onset Pneumonia that will drown you in your own body fluids in a period of hours.

[customwelds]

Yow! Didn't know it could be taht serious! Thank God for this forum, literally. We weld on some galvanized frame regularly for the electrical trades class. We do have a good Smoke-Eater in the shop, but when we weld it is usually in the center of the shop and away from the exaust vents. A friend of mine worked at Tinker AFB for a while and is in the class and warned me to stay out of the smoke as i would get a headache! Good information, but I now know that should have been the least of my worries!

[Thomas Harris]

Keep in mind that there are plenty more nasties besides zinc oxide, in the welding fumes class. Also it's no joke that most metal poisonings stay in the body and can surface later in life with ill effects.

[keyen]

Re: Welding Galvanized Steel

Originally posted by pepster
With this knowledge, I think most of you would agree that it is best to avoid exposure to zinc fumes. If you must weld galvanized steel, either grind away the zinc coating where the welding will occur , weld outside and stay upwind or use an appropriate respirator.

hi,

Can anyone recommend a proper respirator? Would my local welding shop stock one?

[Paychk]

Try this Google search

http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=welding+respirator

Yes, your welding supplier should be able to get them, if they don't stock them.

[horseman1]

"Keep in mind that there are plenty more nasties besides zinc oxide, in the welding fumes class. Also it's no joke that most metal poisonings stay in the body and can surface later in life with ill effects."

Could you elaborate a little. All I was aware of was the zinc gas produced by welding galvinized metal. What other fumes should I avoid? As a matter of practice, I avoid the fumes from stick welding because of the flux but I dont prevent it entirely by using a respirator. Should I wear a respirator all the time? I often use a cheap one when when grinding, since I never liked black snot I would assume that any type of zinc coating would produce this gas, so I would use the same precautions with zinc plated bolts (grind off the zinc before welding them). What other fumes are poisonous or bad for ya ?

Thanks very much,

Kurt

[stever]

Here's a whole list of safety stuff. Welding galvanized metal and just about anything else you may want to know.

http://www.aws.org/technical/FACT-PDF.EXE/SNH.HTM

[Paychk]

Probably the worst commonly available would be cadmium (shinny silver color) plating on bolts. Cadmium is far more common on fasteners than galvanizing (dull aluminum color). Cadmium is a heavy metal and extremely poisonous when in fume form. AWS has this info:

Cadmium Fumes

[pepster]

Thanks stever and Paychk, those are both excellent links. Lots of good information there. Just as a side note, my brother is in the building trades and he advises against holding cadmium plated fasteners in your lips because of the toxicity. I even wear gloves when handling cadmium plated screws.
Pepster

[one_rod]

I'm a industrial maintenance welder by trade and so almost never get the chance to weld on "clean" steel. Its mostly covered in layers of paint and other muck. Its quite easy to find yourself welding on galvanized steel and not even know. The dense white fume and long after-burn are a good indication, but by then its usually too late. I've had mild zinc poisoning and its no fun, like the worst hangover you can imagine and then some! The only real defense is one of those air feed helmets that supply filtered air direct to the welder - simple "nuisanse" dust masks are no good at all. I use an air feed set sometimes but find the hose and belt pack a real hinderance on many tight access jobs. So I sometimes just take a chance and hope for the best.

[Franz]

Welcome to the forum OneRod, hope some of our misuse of the Queen's English doesn't bother you too much.
How did you find our merry band?

[one_rod]

Thanks for the friendly welcome Franz. I found this place through a link from the Old Welder site (I really, really want one of his T-shirts). If you want to hear English getting really mangled then you should listen to some of the people round here speak "Ayup lad as tha not dun that bit o' a job yet?" etc.

On a more serious note horseman1 asks what other types of fumes can be dangerous to welders. A suprising one is the plastic
PTFE(Teflon). Blocks and shims of this stuff are used as anti friction linings on some types of machinery. When doing repair welds its easy to get these parts above a safe temperature.

One of the decomposition products of PTFE is Hydrogen Flouride. If inhaled this dissolves in the moisture in your lungs and becomes Hydroflouric Acid, one of the most corrosive acids known.

Quite a few people suffered permanent lung damage before this
hazard was recognised.

The fumes can also dissolve in moisture on the skin(who does'nt
sweat when they are welding?) and cause chemical burns.

Makes you wonder sometimes if its worth going to work at all.
Stay safe.