Identifying patterns of aerosols formation during contact butt fusion welding

Abstract

The object of research is the hygienic characteristics of harmful substances that pollute the air during contact butt welding with continuous and pulsating melting. The task to be solved is the lack of such information for devising appropriate measures to protect operators of contact welding of railroad rails. A description of the methods of researching the chemical composition of welding aerosols and gases, the dispersed composition of nano-sized fractions of aerosols and assessing their impact on the body of welders is given. It was established that contact butt welding by melting P65 rails is accompanied by the release of harmful substances into the air of the working zone in the form of aerosols at the nano range level, which are characterized by high biological activity. The research results showed that during continuous melting, the intensity of welding aerosol release is lower than during pulsating melting. It is shown that the toxicity of the aerosol during contact welding belongs to the moderately dangerous class. It was established that during contact butt welding by melting, an aerosol is formed, the composition of which contains nano-sized components of manganese and iron in concentrations that exceed the calculated approximately safe levels of human exposure. In the aerosol sample, particles ranging in size from 70.8 to 1071.8 nm were detected, and the average aerodynamic diameter of the aerosol particles was 295.2 nm. The studies have shown that melting butt welding is accompanied by the formation of such toxic gases as nitrogen dioxide and carbon monoxide in concentrations that exceed the maximum permissible. The results of a comprehensive hygienic assessment of aerosols during contact butt fusion welding provided comprehensive information about the level of harmful effects of these aerosols on the body of welders