Thinking of safety and noxious fumes.... Is it safe to weld steel that was Ospho treated? I'm rebuilding my hell hole/battery tray/engine console and I want to give it a thorough Ospho treatment prior to welding.

That's a good question ...

Andy

I'm sure it's too hot there to work with the door open but use a small fan to move the air away from youand you should be in less danger. Even breathing welding fuses is bad for you. I'm sure the OSPHO will add some additional danger.

Actually its more comfortable to work in the garage with the door open and a fan on. I get better circulation. But I would be concerned about keeping gas on my welder tip if I had a fan right on me. Maybe I will put a grinder on the steel where I want to drop some beads after the Ospho.

I'm pretty sure welding the Ospho is relatively safe. But I hear those stories about people getting sick or worse so I don't want to assume too much.

They get sick from galvanize after welding it. That stuff is BAD.

Just crank up your gas and put a fan behind your face. We used to do it all the time in the shop welding galvanize.

My gut is telling me that regular welding fumes is worse than the amount of zinc you might get from welding OSPHO treated metal.

Try to have some type of ventilation anytime you weld.

I know zinc/galvanized is bad. Since Ospho is just Phosphoric Acid, I doubt Zinc is much of a concern.

I remember someone posting a link to a custom bicycle frame builder that became temporarily paralyzed from some kind of solvent fumes when welding. Anyone else recall that?

Try to rig up something that will blow fresh air into your welding helmet. You breathe fresh air and your weld doesn't.

I saw that also, I recall he was welding after cleaning some metal with brake cleaner. Very bad stuff.

I have a cut down snorkel attached to a plastic hose. then I tape a respirator cartrige to the end Apollo13 style. it fits under my helmet.

now about the welding: grind the metal clean in the weld area then treat with 3m or Wurth weld thru primer (zinc rich) any overlapping metal

People tend to use the trade name "Ospho" as a generic name.
But formulations are different. If you look at the MSDS for "Ospho" (brand) you will see that it is just Phosphoric Acid, so it converts the iron oxide into iron phosphate. Another product is the brand name "Metal Ready" (by POR15). In addition to Phosphoric Acid, it also has Zinc Phosphate. Which I believe is what the original poster is asking about. I use the Metal Ready brand and I just make sure I have some type of ventilation when welding.

Regarding the solvents and welding... That is when you weld around chlorinated solvents (such as used in brake cleaner). The UV light from the arc converts the chlorinated solvent into phosgene gas (used in WWI as a poison gas in trench warfare)

This is why I used non-chlorinated brake cleaner.

Not that I would want to breathe any unnecessary fumes but the only reason I would want to treat it first is too keep flash rust from forming on bare metal if it's going to be awhile before it gets welded and sealed. I've never had any luck making a non porous weld with a fan blowing the gas away. Rusty metal is bad enough as it is.