I’m going to be doing a bit of stainless steel welding shortly. I know that the fumes can be dangerous, mostly because of hexavalent chromium, but I’m having a hard time getting the following question answered:
Exactly what do I need to do to keep myself safe while welding stainless steel?
Update 4-12-09: Here is the answer.
We’ll be welding a lot in an only moderately well ventilated building. Running 2 MIG welders for maybe 3 hours a night for 90 days.
I’ve found some tremendously detailed documents but nothing that gives a reasonable guide to safety.
For example, this page reads:
OSHA does not believe that a specific requirement mandating use of HEPA filters for air purifying respirators used for protection from Cr(VI) is justified, and has not included such a requirement in the final rule. For air-purifying respirators, in addition to the option of providing a respirator equipped with a filter certified by NIOSH under 30 CFR Part 11 as a HEPA filter, the Respiratory Protection standard allows employers several alternatives. Under 1910.134 the employer may also provide either (1) An air-purifying respirator equipped with a filter certified for particulates by NIOSH under 42 CFR Part 84; or (2) an air-purifying respirator equipped with any filter certified for particulates by NIOSH where dealing with contaminants consisting primarily of particles with mass median aerodynamic diameters (MMAD) of at least 2 micrometers. OSHA believes these requirements are appropriate for protection from exposures to Cr(VI).
That’s well and good but the standard respirator rating systems don’t talk about 2 micrometer particles. An N95 mask filters 95% of 0.3 micron particles. First, is 95% enough? Second, how good is it at 0.2 micron particles? 94% or 20%???
That document mentions things like “The final rule establishes an 8-hour time-weighted average (TWA) exposure limit of 5 micrograms of Cr(VI) per cubic meter of air (5 [mu]g/m\3\)”. That’s fine but I have NO idea what kind of exposure rate I might get with welding stainless steel. Maybe a gentle breeze will completely protect me, or maybe it’ll kill every living thing in in a 2 mile radius.
I’ll continue my research but I’m bothered that my research is going so slowly. Where can I get answers?