Posted By Shariq Naseem Hi! I have been asked to come up with some guidance material for staff and contractors required to undertake welding in confined spaces or on vessels used for storing fuel. I'll appreciate any leads to where can I find the information. Regards Shariq

Posted By Jane Blunt Dear Shariq There is quite a lot of literature to help you. It would help first of all if you could identify your welding processes. The power source is either going to be electric - i.e. arc welding, or gas, i.e. probably oxyacetylene. Having done that you should research the process a little further, as the potential to produce fume is very different for the various processes. The commonest welding process 'in the field', which has a person holding a short covered electrode (Manual metal arc) tends to produce the most fume. Fume control is much more of a challenge in a confined space. You need to consider both the possibility of oxygen depletion, but also oxygen enrichment, if the process introduces oxygen into the space (either as a result of cutting operations, or along with acetylene). If the process is electric, there may well be an increased risk of electrocution (see the case against Friskies Pet Food) if the walls of the vessels are conducting. In this case, you may need a welding power source with a limited open circuit voltage, and you may need to take special precautions to prevent electrocution. If the process is oxyacetylene, the possibility of creating an explosive atmosphere should be considered as well. If your workmen are pre-heating using propane, you need to consider what may happen to unburnt gases. When preheating there is a substantial risk of producing oxides of nitrogen in high concentrations. (Fatal poisonings have been recorded - the symptoms are delayed until several hours later). The vessel itself, if it has contained flammable mnaterial is also a source of danger. There are publications on how to remove flammable residues and vapours. You will probably need specialist help. Some useful publications: Search The HSE Bookfinder site,http://www.hsebooks.co.uk/homepage2.html using the key words 'welding' and gas freeing'. Books I would recommend to you are: Safe use of compressed gases in welding, flame cutting and allied processes HSG 139 Health and safety in arc welding HSG 204 Control of exposure to fume EH 55, and also EH 54 (but note that the exposure limits listed in these documents have been superseded) CLeaning and gas freeing of tanks containing flammable residues, CS15 Hot work on small tanks and drums INDG314. You may find other titles are also useful. Jane