Posted By Robin V Boughton You should undertake an assessment under the COSHH Regulations and assess the risks to health in a systematic manner. Welding fumes are hazardous to health and can cause drowsiness etc if personel are not properly protected.A seat of the pants approach is not wise. Some form of RPE may be appropriate rather than portable extraction equipment.

Posted By John Murgatroyd The guys should wear Rpe, since they are welding stainless as well. The rpe should be of the type that supplies clean filtered air to the headshield. If the type with a separate air pump is used then the filter fitted should be capable of filtering particulates of respirable size. I say stainless especially, because of the risk from hexavalent chromium. As for extraction, if welding in a small room with no forced extraction and welding operations being carried out, then there is also a visibility risk as well as the fume risk. Depending on the shield gas being used the risk from carbon dioxide/monoxide may not be great, but there is also the risk of asphyxiation since the shield gas will be composed of from 80% to 95% argon. When mig welding stainless the shield gas will be 100% high purity argon. There are also the risks from surface contamination of whatever is being welded. If contaminated with various hydrocarbons then there will also be a fire and/or explosion risk. I would say: RPE, minimum air fed. With extraction as well or better ventilation. A typical analysis of weld fume recently carried out, using the mig/mag process on mild steel with good ventilation and no extraction, with measuring equipment at the welders face was: Iron oxide 8.13 mg/cuM Manganese 1.39 mg/cuM Chromium3 0.139 mg/cuM Copper 0.107 mg/cuM The tests were of 2 hour duration and the results extrapolated for an 8 hour work period. the results exceeded the specified OEL for total welding fume and exceeded the limit for iron oxide in the welding fume calculation. These results can be considered typical !! You should also consider that the iron oxide level was also exceeded by another operative 30 feet away and NOT welding.

Posted By Jane Blunt In MIG welding most of the chromium is released in the trivalent state, which is less hazardous. In manual metal arc welding most of the chromium is in the hexavalent state. Don't forget that extraction is higher up the hierarchy of controls than RPE. You can also vary the fume emission rate by changing the mode of transfer in MIG. The highest rates occur with spray transfer, and dip transfer the lowest. A full gas bottle contains approximately 10 cubic metres of gas (in round figures) so you can estimate what effect this would have on the total quantity of oxygen in your room. Calculate the volume of your room, subtract 10 cubic metres, and calculate 21% of the result - this, in a very simple model is how much oxygen you have. Take this figure and divide by the volume of the room. If the result is less than 18% you could have a problem if the contents of the whole bottle was released. If it isn't, your risk of asphyxiation is not significant. You give your room dimension as 19 foot square. Thus, if your room is 70 cubic metres, the above calculation reveals that you could have 18% oxygen left if the WHOLE gas bottle emptied itself into the room and there was no replacement of air in that time. Note that the portable extraction units only filter the air - which is ideal for particulate fume. They won't help with the argon, but the calculation above suggests that it is not likely to be a problem in any event. Jane

Posted By John Murgatroyd And the fume from mma welding stainless steel (used more often than mig, because the shield gas for mig is more expensive and many workplaces don't stock either high purity argon or the 1.5% Ar/O2 or stainshield gases) contains up to 8% chromium and significant amounts as hex chromium. Please read this webpage.... Until you've tried welding in confined spaces you won't know the effects. The fume in such an area will be considerable, especially welding mma stainless steel. Note that many consumables use higher levels of chromium/nickel than the workpieces being welded. Note also the ozone presence. http://www.twi.co.uk/j32...otected/band_3/jk31.html