During welding with hand-held spot-welding guns, violation of the exposure limit values (permissible values to the German BGV B11) for the magnetic fields cannot be excluded. Whether violation of the permissible values presents a hazard to the welder’s health, however, depends upon the effects of the fields within the exposed body. In the project described here, the exposure of welders during tasks involving hand-held spot-welding guns with separate 50 Hz AC power supplies was assessed for the first time with reference not only to results from workplace measurements, but also to calculated body current densities. For frequent work situations, body current densities were calculated and visualized in a three-dimensional field simulation in multiple layers of the body (genitals, torso, neck and head).
The results were compared with the basic limit values currently applicable for the central nervous system (spinal cord and brain), and evaluated. Violations of the limit values in various fat and muscle tissues and in the spinal fluid (liquor) were found here to be possible, depending upon the interval, position and orientation of the spot-welding gun with respect to the body model; the limit values were however found to be observed within the central nervous system (brain and spinal cord). In all work situations, a maximum of 10 to 20% (1 mA/m2) of the basic limit value was exploited in the central nervous system; the magnetic flux densities lay above the derived limit values.
The report can be downloaded at: http://www.dguv.de/webcode.jsp?q=e159701
Contact: Fritz Boerner, Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung (IFA), Sankt Augustin, firstname.lastname@example.org