Arc welding generates welding fume that is hazardous for human health. A team from the Far Eastern Federal University in Russia, with other colleagues in Russia and Greece, has focused on the key characteristics, as well as dispersion models, of welding fumes within a work zone. An open-access paper on their work is published in Scientific Reports.

The team used common commercial electrodes with various types of coverings (rutile, basic, acidic and rutile-cellulose) in a series of experiments on arc welding operations, under 100 and 150 amps of electric current.

Scanning Electron Microscopy images of the morphological types of solid particulates condensed from vapor during welding using the covered electrode UONI-13/55 of the basic type — general view (a), tree-like (coral) (a, insert), solid (b), hollow (c), perforated (d), sharp-edged (e) and ‘nucleus-shell’ structures (e, insert). Kirichenko et al.

The researchers found that regardless of the types of electrodes used, oxide particles of iron, manganese, silicon (about 41, 18 and 6 percent, respectively), as well as chromium, get into the welding fume.

The morphology of these particles is represented by solid and hollow spheres, ‘nucleus-shell’ structures, perforated spheres, sharp-edged plates, agglomerates of the tree-like (coral) shape. Their average diameter is 5 nanometers, which allows including them into the group of harmful nanoparticles. The smallest and consequently the most harmful nanoparticles form air suspensions in the human respiratory zone.

The chemical compounds formed in the process of arc welding and infiltrating the human body through the respiratory system are toxic because they contain metal oxidation products. Particularly dangerous are welding particles approaching the size of 1 nanometer. From previous studies, we know that such nanoparticles are able to translocate even into the central nervous system (CNS).—Kirill Golokhvast, Vice President for Research of the Far Eastern Federal University (FEFU), professor of Russian Academy of Sciences (RAS), MD, Ph.D., ERT

During welding, about 3% of the electrode and a small part of the material being welded are vaporized. The resulting welding fume contains micro- and nanoparticles of metal oxides. Such particles form air suspensions, which can be evenly distributed throughout the working space. Moreover, such welding suspensions can easily move far beyond the working area along with the air flow.

The researchers believe that this mechanism should be taken into account when safety regulations are elaborated to protect the health of workers. At the same time, the modernization of safety measures will not be possible without the detailed information gathering on how exactly the harmful welding nanoparticles are formed, what shape they are and what elements are contained in their composition.

Currently, there is no common point of view on how the parameters of welding —methods, electricity current strength (amperage), etc.—affect the volume of welding fume and, accordingly, the level of emission of harmful nanoparticles. Some suggest that an increased current strength reduces vaporization during welding. Others point out that the strength of the current is always proportional to the melting point of the metals being welded, which in turn increases the volume of vapor formation.

According to the results of this study, arc-welding operations prove once again to be procedures with high levels of hazard for human health. These results help improve our understanding of risks that these operations pose to human health and may strengthen the need for their control and mitigation. The introduction of 3D modeling of particle size dispersion of WF, during welding arc operations, proves to be an appropriate method for their characterization.—Kirichenko et al.

This study was supported by Priority Project of the FEFU “Materials”.

K. Yu. Kirichenko, A. I. Agoshkov, V. A. Drozd, A. V. Gridasov, A. S. Kholodov, S. P. Kobylyakov, D. Yu. Kosyanov, A. M. Zakharenko, A. A. Karabtsov, S. R. Shimanskii, A. K. Stratidakis, Ya. O. Mezhuev, A. M. Tsatsakis & K. S. Golokhvast (2018) “Characterization of fume particles generated during arc welding with various covered electrodes” Scientific Reports volume 8, Article number: 17169 doi: 10.1038/s41598-018-35494-1

Posted on 09 December 2018 in Emissions, Health, Manufacturing | Permalink | Comments (0)

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