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KMID : 0895420030130030207
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Journal of Korean Society of Occupational and Enviromental Hygiene
2003 Volume.13 No. 3 p.207 ~ p.216
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New ISO Procedure for the Evaluation of Hazardous Metals Having Soluble Occupational Exposure Limits
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Yoon Chung-Sik
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Abstract
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This study was performed to investigate the total (insoluble+ soluble) metal contents and soluble metal contents in flux cored arc welding fumes. A well designed fume collection chamber for welding operations was used for fluxcored arc welding with CO2gas. Nine different products of 1.2 mm diameter flux-cored wires, five of which were for stainless steel welding applications and the others were for non-stainless welding. Ashing for total metal compositions were treated by NIOSH 7300 method and soluble metals were extracted by newly developed ISO 15202-2(Annex B). Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was used to analyze 13 different metal components. The contents of all metals were 47.6% in the nonstainless welding fumes whereas 36.4% in the stainless welding fumes. But the soluble contents of all metals were higher in stainless welding fume than in non-stainless welding fumes(15.% vs 8.3%). The reason that soluble fractions are higher in stainless welding fumes is that there are high levels of potassium and sodium, which contribute other metals to be solubles. Hexavalent chromium, A known human carcinogen, can easily be soluble by combining with potassium and sodium. Total chromium content in stainless welding fumes were 3.8 (2.8-5.2)% and soluble content was 0.8(0.4-1.2)%. So, the soluble fraction of chromium was 21.3% in stainless flux cored arc welding fumes. The content of aluminum was exceptionally high in self-shielded flux cored wire fume(product ’D’). The reason is that aluminum is added as a de-gassing agent that protect the melting part from the nitrogen and oxygen. It was found that soluble chromium concentration should be evaluated for stainless flux cored arc welding. This study revealed that how to use the fume concentration and/or total(insoluble + soluble) metal concen- tration to estimate soluble concentration of
occupational exposure limit designated metals. The metal compositions of flux cored arc welding fumes were similar to those of shielded metal arc welding whereas welding method of flux cored arc welding were similar to that of metal gas arc welding(MIG or MAG), which were mainly explained by flux existed in both flux cored arc welding and shielded metal arc welding.
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KEYWORD
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Solubilit, Flux, Welding, Fume, ISO, Chromium, OEL, Flux-cored arc welding
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