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.
Photoprotection by Workwear: Ultraviolet Protection Factors for Artificial Radiation from Welding Arcs
Photoprotection by clothing is one of the most effective protective measures against solar ultraviolet radiation (UVR), and the related concept of UV protection factors (UPF) for fabrics has proven itself for decades. Although immense work has been carried out regarding factors influencing textile sun protection, the idea of UPFs for artificial UVR, if necessary with different action spectra, is payed little attention. In this work, a modified UPF equation is proposed utilizing welding arcs and the ICNIRP action spectrum. These welding UPFs (wUPF) were calculated for some workwear as a function of welding power, technique and welded material. No wUPF welding power dependence existed. By means of normalized standard emission spectra, that were further clustered with regard to welding technique, it was found that the wUPF depends exclusively on the fabric’s transmittance and the ICNIRP weighting function yielding a reduced wUPF formula. Finally, a comparison of solar and welding UPFs, based on either their full or reduced equations, is discussed.
Skin and eye diseases among arc welders those exposed to welding operations.
The prevalence of skin and eye abnormalities was determined in 77 journeymen welders, 75 members of other trades exposed to welding operations and 58 non-exposed comparison workers. Characteristics including possible risk factors for skin cancer were compared among the groups. Localized cutaneous erythema was frequent in welders and occasional in other exposed workers. Small cutaneous scars were frequent in welders. There was no significant difference in the prevalence of actinic elastosis by occupational group; however, the degree of elastosis was significantly associated with type of complexion, original hair color, eye color, childhood freckling poor ability to tan and ease of sunburning. There were no significant difference among the groups in the prevalence of various dermatoses, skin tumors, alterations in visual acuity or clinical ocular abnormalities on slit lamp biomicroscopy and fundoscopy apart from variations in the amount of dust in the lids. The observed prevalences of skin and eye diseases may provide useful comparative data.