Brazing/soldering galvanised steel

[chillybilly]

need advice ,have to braze the crosshead and the only dia pipe available is galvanised .
I have machined the areas to be brazed so thats in the clear ,question being am i going to poison myself from the remaining galvo getting warm ????

not going to have a go until i no more ,could do without doin myself in ,not finished the engine yet

 

[chillybilly]

Looks like need to get the galvo off ...ho hum glad i checked


"According to the American Welding Society, Metal Fume Fever is an illness caused by exposure to zinc oxide, a chemical present in fumes from welding and brazing galvanized metal. The symptoms of metal fume fever are flu-like, including headache, nausea, fever, fatigue, and chills. Symptoms start several hours after exposure and last 6 to 24 hours, although total recovery might not be for 48 hours. High levels of exposure may cause metallic taste in mouth, dry and irritated throat, and coughing. Several hours after exposure, you may have a fever (lower than 102 degrees F, then chills before returning to normal). The OSHA standard for zinc oxide exposure is 5 miligrams per cubic meter of air averaged over an 8 hour work shift. NIOSH uses the same 5 mg per m3 (cubic meter), but suggests that it is permissible for 10 hours per day, or 40 hours per week. They further permit a STEL (short term exposure limit) of 10 mg/m3 averaged over a 15 minute period. There is no published information about long term effects of zinc oxide exposure. (American Welding Society. Safety and Health Fact Sheet No. 25) Even though there are no known long term effects, it doesn't make sense to expose yourself to zinc oxide and potentially suffer from Metal Fume Fever, because it's easy to prevent exposure. Brazing, as opposed to welding, produces fewer fumes because of the lower temperatures."

 

[Artie]

Gday Chilly, long before we knew gal was nasty stuff we used to make farm gates out of it and Ive literally welded dozens of joints with just the weld centre ground free of gal.

My point is ... yes it is nasty stuff and repeated exposure can cause issues BUT with a little care such as using a breathing filter, covered arms and legs and minimal exposure you can be reasonably sure of avoiding any issues. Thats in MY case, but I dont tend to suffer from many maladies or chemical reactions at all. Others who may have sensitive constitutions may wish to avoid it entirely.

In my case, I would remove it as much as possible (sanding) and put on safety gear and solder/braze it with some ventilation.

Cheers mate.

Rob

 

[Richard1]

My father spent half a life time welding galv iron. Mostly it seemed to have no visible effect on him but he did very rarely suffer from what he called the zinc shakes. I presume this was metal fume fever. Whatever it was drinking a pint of milk seemed to cure it. There are suggestions on the net that the zinc fume somehow takes calcium from the body causing the symptoms. I have no idea of the truth of this.

 

[chillybilly]

thanks lads ,bit of common and some sandinig should see the job done . Will get on this eve ,watch this space ....

 

[Noitoen]

When in school, we used to "soft solder" galvanized sheet metal and just before the soldering, we just cleaned the joint with sulphuric acid to remove the zinc just around the joint, which was then "replaced" with solder, and would maintain the anti-corrosive properties.

 

[Bill S]

Ventilation is the key. For soft soldering you have fumes from the zinc as well as the sulfuric acid. For welding the zinc fumes are pretty intense. Both would require good ventilation, A simple fan pushing the fumes away would suffice, but if you are indoors the fumes will build up so you may need to exhaust them. Doing the deed outdoors would be better, but I would still use a fan. If the zinc is machined or ground away from the area to be soldered or brazed then the fumes would be greatly reduced. I have never brazed galv with torch, but we used to use a carbon arc method with a copper alloy rod called Everduar to join galv sheet. It was weaker than welding, but just as strong as soldering.

Bill

 

[chillybilly]

Pleased to annouce that the brazing job went all ok ,joint ran really well actually :big:

Thanks for the words of advice ,machinig the two dia's that were to be brazed and getting rid of the Zinc in the immediate area seemed to do the trick .

Now all i need to do is bore out the guide and i am cooking with gas !

Could be tricky 5.5" long 2.125" bore pipe ,steady not big enough ....
Could be fun !!!!!!!!!!!!!!!