PWC,

Ed's experience seems to have ample relevance to your problem and he raised good points at his site.

I am fortunate that a very simple ventilation scheme has apparently been satisfactory for my low production rate and the small levels of fumes I produce. (on a less serious tone my associates note that I produce even less fumes when I avoid Mexican food- but thats a personal issue)
I believe the AWS journal covered ventilation in their issue fearturing safety and health; Feb '01... I am not certain, but thats where I would look.

If you were unfortunately serious about the globular troubles, have you considered raising the CO2 proportion slightly to increase the useable short circuit range of parameters, (to 10-20% CO2; I prefer ac15) I am puzzled by your choice of gas to serve as an all purpose mix. Here, again, Ed Craig can be of help.

Regards
d

In every shop that I have worked in or inspected in (Other than in the navy and in high school) . The shops do nothing. Unlike steel toed boots and safety glasses, respiritory protection is an expensive safety issue. Not only does the initial survey, monitoring and installation of adequate ventilation cost, those cases in which ventilation is not adequate require special respiratory protection which usually slows down production.

The threshold limit values listed in 29CFR1926.55 Appendix A are probably not checked in many fab shops. The positions encountered and various configurations of assemblies could make monitoring difficult. I have seen surveys done where the welder who was welding on the table/jackstand was fitted with the sampling instrument while I was in the bottom of a smoke filled tank pulling the trigger on a FCAW gun.

Many shops may very well take measures to minimize long term health risks associated with metalworking (See the report from the boilermakers). I just haven't been in one yet. Also consider the people working in the field. The conditions encountered there include welding on or around unknown coatings/lubricants, dust from the process etc..

I suggest that all people who weld become familar with the MSDS for the material they are working with and understand the protection provided by the code of federal regulations. There is more to OSHA than steel toed boots, safety glasses and tying off.

Use discretion when you tell the employer about what they have to do to comply with OSHA but always protect yourself.

Here is an excerpt from a report done by the boilermakers in Kansas City. This text is from the conclusion section
"The results of the sampling data showed that the welders were exposed to high levels of stainless steel welding fume almost two thirds of the time during the study. Several of the personal samples were extremely high; the highest level of welding fume measured on a welder was 60 mg/m3, almost 12 times ACGIH's TLV of 5 mg/m3. In addition to exceeding the recommended levels for total welding fume, many of the personal and area samples exceeded levels set for arsenic, total chromium, hexavalent chromium, iron, manganese, and nickel. Nickel and hexavalent chromium are both considered potential occupational carcinogens by NIOSH. Personal exposure levels reached almost 0.7 mg/m3 for nickel (REL=0.015 mg/m3), and almost 3 mg/m3 for hexavalent chromium (REL=0.001 mg/m3). "

This entire report can be read at http://www.osha.gov/SLTC/weldingcuttingbrazing/report_boilermakers/boilermakers.html and explains how the testing/sampling was performed.


Have a nice day

Gerald Austin
http://www.weldinginspectionsvcs.com

Some background information regarding PEL's and effects of various substances can be viewed at http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=PREAMBLES&p_id=770&p_search_str=&p_search_type=&p_status=CURRENT&p_text_version=TRUE


Good Night

Gerald Austin

A couple of years ago I participated in our company review of our respirator/ hazardous fume policies. It was interesting to say the least. Unfortunately, with welding being what it is, you can't prevent fume generation. What you can do is to reduce or eliminate the welder's exposure. Probably the most important thing you can do is to provide or increase your ventilation. This can be as simple as opening a door or as complicated as installing an air cleaning system. Every situation is different, and cost vary a lot.
What we didn't want to do is to make everyone wear more equipment, because if your employees are uncomfortable, they probably won't use the equipment, unless you stand right there making them do it. And if you do that, then you need to wear the equipment too. And soon you'll be trying to hire more welders to replace the ones that quit. Catch 22.

We are in-process of installing heat recovery ventilation units to keep the overall fume levels lower (plasma- cutting generates a LOT of fume but is often overlooked) and the welders have respirators available. Also, we have some "smoke-sucker" welding guns which are effective (but aren't popular because of bulk and weight). And we have "portable" smoke extractors that help too.
Since we use mostly FCAW, we looked at different wires to use. Salesmen will tell you their products have reduced smoke/fume but side by side comparisons at equal volts/amps settings (very important to compare apples to apples) didn't show that. Metal cored products or GMAW did show less fume but much higher copper fume and very high ozone because of the argon shielding. Ozone can't be filtered out, you have to ventilate or provide air supplied respirators.

You may want to do a longer term air quality study. When I was in production, it always seemed that air sampling was scheduled on windy days with the bay doors open and little welding was happening compared to the day before. So the welders "compensated" by putting the intake hose right next to the welding gun when no one was looking. If sampling were done over a period of time you might see different numbers.

So anyway, I didn,t intend to add to your anxiety. Check with your vendors, and go online for more info on effective equipment, but beware of "snake oil". And it is very important to train and educate your employees, not just welders. Teach them when and how to ventilate, how to keep their head out of the smoke, and when they need a respirator. You need to persuade a change in culture rather than enforce more rules.

Good luck,
CHGuilford