Hello, looking for some ideas on how others have engineered out the presence of hexavalent chromium during the welding process of stainless steel. Have been given advice on everything from respirators to fume collectors. Curious what others have used and to what success.
We do all TIG welding with no smoke. We have never measured to see what the levels are. We do use standard industrial fume extractors over the welds for our manual workstations. We have some automated set-ups that are welded in enclosures with no fume extraction. My understanding is that it is more of a concern with the SMAW process with all the smoke.
There was a big study of Cr-VI emissions from shipyards done recently. The paper used to be up on the NSRP website, but here's the reference:
Industry-Wide Survey for Hexavalent Chromium (CrVI) Exposures in Shipyard Operations,
Atrium Environmental Health and Safety Services, LLC, October 2007.
Basically, stick and flux cored on high Cr electrodes is an issue, a very big issue. MIG can be an issue when using high Cr electrodes, but not nearly as much. TIG was under the 2.5 ug/m3 limit. For those who get the paper, I'm looking at Figure A, page 2.
I do quite a bit of stainless, GTAW,GMAW and Gmaw Automatic. We had an industrial Hygenist come in and do some fume measurements....The highest he found was on the automatic work station where it was only approaching the "high end of what's OK ". We installed a local fume extraction system over the automatic weld cells and the issue disapeared for us.
We did a study with and had a rep. from an outside testing company come in and monitor the shop before and during the GMAW welding of S/S. We already had bought one of the Lincoln smoke eater units which is basically a big vaucmn on wheels with a telescoping "snorkel" on it that can be moved around to directly over the actual weld.
It works good and it has a light built into it and it has one setting that once you start the arc, it starts automatically and when you stop, it shuts off.
The interesting part was once the testing was done by the outside health department, the levels were so low that we were not required to use the unit, but we had already bought it months before.
I was not directly involved in this testing/ process, as QC I was aware it was going on. They did put actual moniters of some type all over the guy doing the welding and grinding for the entire day. Again, it worked out that the exposure levels were below the levels required.
What about plasma cutting 304 and 316 stainless. We cut a lot of stainless with the plasma and the smoke is crazy bad. There was never any testing done on the guys who do all the cutting, just the welders.
By OBEWAN 
Date 05-01-2009 13:06
Edited 05-01-2009 13:11
If they did testing, it seems like they dropped the ball on the cutting. If I were there, I would have pushed for testing the cutters while the guy was in to do the other tests. It only makes sense. You might be able to Google for some reports on hexavalent chrome and plasma cutting.
Here is a Navy report from Shipyard Testing that includes plasma cutting:
safetycenter.navy.mil/osh/shore/downloads/NSRP_Hexavalent_Chromium_Exposures-0108.pdf
Because OSHA is interested in what the operator breathes in, not the total amount that's expelled into the air (that's the EPA's concern), you may not have an issue depending on where your operator it, how large the room is, how the ventilation in the room is, and the list goes on. The paper I cited earlier had 7 plasma cutting readings from various yards, and on high Cr materials, the readings spread from 1 to 6.5 ug/M^3 of Cr-VI. Basically, you should probably do some testing to see where you're at.
Yes. I guess that makes sense. I was thinking about a manual cutting operator with his head over the smoke plume. On a big gantry cutter he might not be exposed.
Yeah these guys are hand cutting sheets all day. I guess our safety guy didn't think about that.
We did a study of hexavalent chromium formation for a number of different GMAW processes, and were able to show that some process/shield gas combinations are much worse than others. So there are some best and worst choices for welding stainless and other chromium alloys. We adjusted the results so that they were all ranked in terms of rates of hexavalent chromium per unit of wire used, since the feed rates of wire were different for some of the processes. The best 2 processes were a short-arc 75% Helium/25 % argon process, and a pulsed axial spray method using 98 % argon/2% oxygen. We did not include in the study, but stick or flux-cored produced much more hexavalent chromium. Axial spray methods were generally much heavier producers of hexavalent chromium than short-arc methods. We hope to evaluate some other techniques in future studies. The published study is “Hexavalent chromium content in stainless steel welding fumes is dependent on the welding process and shield gas type” in Journal of Environmental Monitoring, Vol.11, no. 2, February, 2009, pp. 418-424.
Disclaimer
The findings and conclusions in this paper are those of the author and do not necessarily represent the views of the National Institute for Occupational Safety and Health. The mention of any company names or products does not imply an endorsement by NIOSH or the Centers for Disease Control and Prevention, nor does it imply that alternative products are unavailable, or unable to be substituted after appropriate evaluation.
Michael Keane
Mjk3@cdc.gov
By aevald 
Date 06-05-2009 19:55
Edited 06-05-2009 23:57
Hello Michael, thank you for posting up this information. I haven't had the opportunity to look up that specific paper, but certainly will. I believe many others on the site will be doing so as well. Welcome to the forum and thanks for the contribution. Best regards, Allan
We have some new information regarding hexavalent chromium generation and reduction, created in laboratory conditions and using the American Welding Society-specified fume collection chamber. This study confirms and extends the previous findings, and we have a lot of confidence in the quantitative emission rates. Here is the paper citation:
Keane, M., Siert, A., Stone, S., Chen, B., Slaven, J., Cumpsten, A., and Antonini, J. Selecting processes to minimize hexavalent chromium from stainless steel welding. Welding Journal 91(9):241-246S (2012).
We have also done some work with some advanced, complex-waveform welding processes, including Surface Tension Transfer, Cold Metal Transfer, and Regulated Metal Deposition, all of which are very promising for reducing fume and hexavalent chromium emissions from stainless steel welding. We will post that information here when it is published.
If anyone needs more information or reprints of the paper(s), please write at the address below.
The findings and conclusions in this paper are those of the author and do not necessarily represent the views of the National Institute for Occupational Safety and Health. The mention of any company names or products does not imply an endorsement by NIOSH or the Centers for Disease Control and Prevention, nor does it imply that alternative products are unavailable, or unable to be substituted after appropriate evaluation.
Michael Keane
Mjk3@cdc.gov
