Mathematical Modeling of Optical Radiation Emission as a Function of Welding Power during Gas Shielded Metal Arc Welding
Abstract Arc welding is accompanied by intense optical radiation emission that can be detrimental not only for the welder himself but also for people working nearby or for passersby. Technological progress advances continuously in the field of joining, so an up-to-date radiation database is necessary. Additionally, many literature irradiance data have been measured for a few welding currents or for parts of the optical spectral region only. Within this paper, a comprehensive study of contemporary metal active gas, metal inert gas, and cold metal transfer welding is presented covering optical radiation emission from 200 up to 2,700 nm by means of (spectro-) radiometric measurements. The investigated welding currents range from 70 to 350 A, reflecting values usually applied in industry. Based upon these new irradiance data, three mathematical models were derived in order to describe optical radiation emission as a function of welding power. The linear, exponential, and sigmoidal emission models depend on the process variant (standard or pulsed) as well as on the welding material (mild and stainless steel, aluminum). In conjunction with the corresponding exposure limit values for incoherent optical radiation maximum permissible exposure durations were calculated as a function of welding power. Typical times are shorter than 1 s for the ultraviolet spectral region and range from 1 to 10 s for visible radiation. For the infrared regime, exposure durations are of the order of minutes to hours. Finally, a validation of the metal active gas emission models was carried out with manual arc welding.
MEASURING EYE FLASH FROM ARC WELDING
In our shipyards today we are employing over 100,000 welders. These workers and their neighbors have a certain amount of exposure to ultraviolet radiation, although every effort is made to supply and use suitable eye shields, goggles and screens. About 40 per cent of the calls at our shipyard dispensaries are because the patient has received what he thinks may be an "eye flash." 1 Our purpose in the present study was to derive a practical rule whereby one can estimate in terms of time, intensity of radiation and distance the safeness of any exposure to a welding arc. Verhoeff and Bell 2 showed that the ultraviolet radiations responsible for ocular lesions in rabbits were shorter than 305 millimicrons and that about 2 × 10 6 erg seconds per square centimeter were required for a minimal effect. They also showed that the biologic response varied with the duration of the
Field study of potential ultraviolet exposure from arc welding
Ultraviolet emissions for a variety of welding operations and conditions were measured. The effect of distance on the uv levels was measured, and the effect of smoke and fume on these levels is indicated. The performance of several clear safety glasses for the attenuation of actinically weighted uv is evaluated. (auth)