When welding galvanised steel, a simple ventilation system reduces employees’ exposure to fume
An organisation’s plumbers frequently had to fabricate small items e.g. gates, simple frame work etc., from galvanised steel. Arc welding this type of material may produce fumes containing zinc oxide generated from the galvanised coating of the product being welded. Besides zinc oxide, welding of galvanised materials may produce ozone, phosgene and carbon monoxide, all of which can be hazardous.
The supervisor discussed the problem with the plumbers. Along with budgetary requirements, various control options were considered by the group and eventually an ‘in-house’ solution to the problem was recommended as being the most effective.
Ducting for an exhaust system was fabricated from used piping and fittings which were already available. A ‘Vac-U-Mac’ system (which operates off an existing compressed air system) was purchased and this was attached to an empty 200 litre drum. Lengths of flexible hose were connected to the ducting with a capture hood fabricated and attached to the flexible hose. To ensure the capture hood of the system could be located at the point of fume generation, a clamping device was fitted around the neck of the hood (a magnet could be used instead of the clamp and is often more versatile). The re-usable drum is regularly maintained and emptied in a safe manner.
Hierarchy of Controls:
Administration – consultation
- Plumbers and sheet metal workers are now able to weld galvanised steel without being exposed to dangerous fumes.
- The risk to other employees working in the area has also been minimised.
- The plumbers performing welding have no hesitation in using the exhaust system they helped to design and manufacture.
- The fume exhaust system has been successfully operating for the past three years.