Three steps to fully analyse welding fumes
| Thin Organic Coatings are widely used in a variety of industries to prevent corrosion of metals. These coatings – usually a thin layer of a few microns on the metal surface – are designed to allow welding. During this welding process, thermal degradation compounds are generated and hence possibly implying a health risk. Especially when developing new coatings, it is crucial to investigate this potential health risk. At OCAS, there is an extensive spectrum of sampling (from gas to dust) and analytical techniques available (from composition to morphology) to perform such risk assessments. |
"One of our customers – a coating supplier – provided us with a metallic sheet coated with a Thin Organic Coating (TOC),” explains Veerle Van Lierde, Research Engineer materials characterisation & testing at OCAS. “We tested the sample on the release of possible hazardous compounds during spot welding. The most important questions our customer had, were: what are the main volatiles released during spot welding and do they represent a potential health and safety risk? Using the OCAS pyrolysis system, we simulated the welding process as a first screening method (according to ISO 15011-5).” “We scraped off a small amount of the sample and introduced it into the pyrolysis system. The sample was submitted to 600°C and 800°C in order to simulate the welding conditions. Our pyrolysis is coupled with GC-MS (Gas Chromatography and Mass Spectrometry). The gas chromatograph separates the thermally fragmented species, and the mass spectrometer detects and identifies them. This screening test gives both qualitative and semi-quantitative results of the main volatile organic compounds generated during welding.” |
Next step: Toxibox “After the pyrolysis, a laboratory welding test was performed using the OCAS Toxibox, a self-engineered piece of equipment. This allows efficient gas and dust sampling for further quantification. The resistance spot welding Toxibox was placed around the electrodes of the welding equipment, and the dust and gases released during welding were sampled and further analysed (according to ISO 15011-6). Based on the results obtained from the pyrolysis and the welding test using our Toxibox, a risk assessment was made. The outcome for our customer was unfortunately not so positive. Concerning the gases, the concentrations of the pollutants were just above the exposure limits. The concentrations of the dust, however, were significantly above the exposure limits.” “For this customer, there was an obvious health and safety risk. That is why we also performed a workplace analysis. This is in fact the third step in our welding fumes analysis offer. Only then it is possible to make a complete risk assessment. Thanks to the results from pyrolysis and the laboratory welding test, it was clear which components needed extra attention when we sampled the air quality at the workplace. Based on these preliminary data, a cost and time reducing workplace analysis was possible. This kind of welding fumes analysis is not only useful for coating suppliers, but also for example for arc welding wire suppliers and end-users in the appliances industry,” concludes Veerle Van Lierde. |
