The radiation exposure of welders and their assistants depends essentially on the radiation emitted by the welding arc. Considerable exposure may however arise from reflections, as well as from direct radiation. Earlier measurements showed that reflections may typically account for 0.1 to 1% of direct radiation. It is therefore not sufficient for protection to be guarded against direct radiation alone. The main aim of an IFA project was to study the reflection of ultraviolet (UV) radiation on a range of surfaces.
The irradiance varied as a function of several factors, including the welding current, the distance between the source and the detector, and the distance between the electrode and the workpiece. The welding method selected also had a major influence upon the irradiance: during metal active gas welding, the effective irradiance in the UV range was more than 20-fold compared to the irradiance during pulsed tungsten inert gas welding.
A relationship was also established between the magnitude of the reflected radiation component and the reflecting surface (e.g. its material). For example, it was found that the welding curtains used did not necessarily exhibit the lowest reflection. Altogether, it was confirmed that reflection is in the order of 0.2 to 1.2%.
UV radiation components do not penetrate the helmet. It is assured that protection of the welder’s eyes and facial skin is provided if the helmet is fitted tightly against the face. Where a gap exists between a welder’s helmet and the face, reflected radiation components are able to reach the eyes and the face.
Contact: Dr Marc Wittlich (marc.wittlich@dguv.de)
More information: http://www.dguv.de/webcode/ep76036
