Welding safety

[WQ9E]

I know that some of us get involved in some welding projects for ham radio and other hobbies.  I came across this and it is probably a good safety read for the group, I don't recall seeing it posted here previously:

http://www.brewracingframes.com/id75.htm

[K5WLF]

Wow! I learned something from that article. I don't TIG, but I use 75%Ar/25%CO2 for my MIG, so I imagine it'd do the same thing.

Thanks for sharing that, Rodger.

ldb

[W1RKW]

good warning.  Some refrigerants (older ones) can do the same thing if exposed to open flame.  I have some older electronic chemicals pre-ozone layer destroying types that would probably fall into this situation.  Good stuff if used properly.

[KA0HCP]

The article is in error.

Argon is not a constituent of Phosgene and is not involved in it's formation.   Phosgene is COCl2.   Argon is a 'noble gas' and does not normally react.

Phosgene can be formed by high heat, and by UV rays (from an arc welder) in the presence of oxygen from the atmosphere.

Other compounds that represent a phosgene danger are chlorinated fluorocarbons such as R12, R22 refrigerants and Halon in fire fighting.

Wikipedia has more info.   Bill

[KL7OF]

Wow! I learned something from that article. I don't TIG, but I use 75%Ar/25%CO2 for my MIG, so I imagine it'd do the same thing.

Thanks for sharing that, Rodger.

ldb

Roger..Have you tried 100% CO2 for mig welding steel?...cheaper and works well

[KA0HCP]

Hazards from the World Health Organization file on Phosgene

Paint removers and non-flammable dry cleaning solvents (e.g.,
    carbon tetrachloride, chloroform, tri- and tetrachloroethylene and
    methylene chloride) should never be used in closed areas in the
    presence of fire or heaters of any kind since they can decompose to
    phosgene.  

  One other source mentions burning PVC as a possible source of Phosgene.

Comment:
Injuries from Phosgene exposure are typically limited to the mucous membranes of the mouth, lung, sinuses and eyes. Phosgene decomposes when exposed to the moist mucosa and does not distribute through the body to a significant amount. (WHO)

The additional reactions cited by the author i.e. Tremors/seizure, kidney dysfunction, pancreas/insulin dysfunction, etc.  are not reported as being associated with Phosgene exposure.    They may represent prior existing conditions or perhaps resulted from other chemicals in the mishap environment.

[Opcom]

Hazards from the World Health Organization file on Phosgene

Paint removers and non-flammable dry cleaning solvents (e.g.,
    carbon tetrachloride, chloroform, tri- and tetrachloroethylene and
    methylene chloride) should never be used in closed areas in the
    presence of fire or heaters of any kind since they can decompose to
    phosgene.  

  One other source mentions burning PVC as a possible source of Phosgene.

Comment:
Injuries from Phosgene exposure are typically limited to the mucous membranes of the mouth, lung, sinuses and eyes. Phosgene decomposes when exposed to the moist mucosa and does not distribute through the body to a significant amount. (WHO)

The additional reactions cited by the author i.e. Tremors/seizure, kidney dysfunction, pancreas/insulin dysfunction, etc.  are not reported as being associated with Phosgene exposure.    They may represent prior existing conditions or perhaps resulted from other chemicals in the mishap environment.

PVC - no idea what it does but burning plastic is no good anyway. My friend's sister was burning some scrap PVC from a plumbing truck in a trash barrel and the stench was amazing, but it was the fumes that made her sick. She got one good inhalation of the smoke when she went to look at the fire (still don't know why she did that -said "I don't know"). She was coughing for several minutes and sick as a dog for several hours but refused to be taken to the ER. We would have called in, if she hadn't started feeling better, but the tail end of it did last well into the evening. I don't want to just say it but it was a stupid thing to do.

[K5WLF]

Wow! I learned something from that article. I don't TIG, but I use 75%Ar/25%CO2 for my MIG, so I imagine it'd do the same thing.

Thanks for sharing that, Rodger.

ldb

Roger..Have you tried 100% CO2 for mig welding steel?...cheaper and works well

I find I get less splatter using the Argon/CO2 mix.
ldb