Suchergebnisse

OBJECTIVES: Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and skin erythema. The extent of the hazard of UVR varies depending on the welding process and conditions. Therefore, it is important to identify the levels of UVR present under different conditions. The purpose of this study was to investigate the degree of hazard of UVR emitted by the different types of arc welding of cast iron frequently used in industry. METHODS: In this study, we experimentally measured the UVR emitted during gas tungsten arc welding (GTAW), shielded metal arc welding (SMAW), and gas metal arc welding (GMAW) of cast iron. The degree of hazard of UVR was quantitatively evaluated in accordance with the guidelines of the American Conference of Governmental Industrial Hygienists. RESULTS: Effective irradiances measured in this study were in the range 0.045‐2.2 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels were only 1.4‐67 s/day. CONCLUSIONS: UVR emitted during arc welding of cast iron has the following characteristics: (a) It is more hazardous at higher welding currents. (b) The magnitude of the hazard, which depends on the welding process, increases in the order of GMAW > SMAW > GTAW. (c) It is influenced by the filler material used; that is, the components contained in the filler material affect the hazard of UVR. The effect is Fe > Ni, Cr

Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10–0.91 mW/cm2 at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3–33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc.