Documents welding 28 results

"A longitudinal study was carried out on two groups of workers engaged in tin/lead alloy welding in the telecommunications sector. The risk of exposure was evaluated by measuring levels of airborne lead and concentrations of lead in blood. The correlated effects were assessed by determining zinc protoporphyrin(ZPP) and haemoglobin levels and red blood cell count. Subjective symptoms were also recorded. Results indicated a very low risk of lead exposure during microwelding operations. While blood lead concentrations were significantly higher than those in the general population, they were significantly lower than the Occupational Safety and Health Administration's permissible exposure limit. No variation was found in the other biological parameters investigated, and no health effects were observed. During the study period, the introduction of some technological innovations led to a further reduction in lead exposure and,subsequently, to its total elimination. Blood lead concentrations gradually declined to lower values, and ZPP concentrations also decreased to normal levels, demonstrating that the effect of lead on heme synthesis may occur even at very low levels of lead exposure."

"Un équipement susceptible d'émettre des champs magnétiques sur deux est une soudeuse par résistance. Ces machines exposent les opérateurs à des champs magnétiques élevés susceptibles de dépasser les valeurs déclenchant l'action définies par la directive européenne 2013/45/UE. La réglementation impose aux employeurs d'évaluer le risque du aux rayonnements électromagnétiques (ou de le mesurer) et de prendre les actions nécessaires pour le réduire. La mesure des champs magnétiques émis par les équipements de soudage par résistance permet de mieux appréhender ce dernier mais reste délicate de par la nature impulsive du signal. Une méthode de métrologie pour aider à l'évaluation de ce risque ainsi que des résultats de mesures réalisées aux postes de travail de plus de 100 machines sont présentés."

"Many workers are exposed to a range of particles present on a nanometric scale. In occupational hygiene, it is common to differentiate manufactured nanoparticles (NP) from ultrafine particles (UFP) coming from natural, human or industrial sources. Given that major deficiencies exist in the usual risk assessment approaches for these particles, the objective of this research was to assess occupational UFP and NP exposures. The secondary objective was comprehensive testing of the assessment capabilities regarding occupational NP and UFP exposures in an industrial and laboratory context. Two main types of assessment were performed during this research. The first concerns the assessment of the fine and ultrafine particle concentrations with a particle counter (P-Trak, model 8525), and the second pertains to the assessment of fine and ultrafine particle size distribution with an electrical low pressure impactor (ELPI). The measurements were taken in two welding schools, an aluminium smelter, the research centre of a thermoplastics processing company, and three university laboratories producing and/or using nanoparticles. The results revealed that aluminium smelter workers, people who perform welding tasks, and workers in the thermoplastic processing industry are exposed to UFPs. However, the assessments performed under this study do not reveal high NP concentrations in research laboratories. Only NP production by milling generated detectable NP concentrations. NP handling in glove boxes of two other laboratories seems to prevent worker exposure adequately. There is currently no consensus concerning UFP and NP exposure evaluation measures. However, our findings suggest that the P-Trak is suitable for occupational assessment of UFP concentrations, whereas several uncertainties remain to assess NP exposure, particularly in their agglomerated form. In view of this research, it appears that a characterization and control study of occupational NP and UFP exposure should include assessment of the mass and particle number concentrations, measurement of granulometric distribution and electron microscopic characterization of nanoscale particles."

"Les soudeuses ou presses haute fréquence fonctionnant sur le principe des pertes diélectriques sont utilisées dans la fabrication de produits à base de polymères isolants. Ces opérations de soudage sont essentiellement manuelles sur les soudeuses destinées aux grandes pièces. Elles nécessitent la présence constante d'un, voire deux, opérateurs qui, sur les machines de conception ancienne, sont exposés à un niveau de champ électrique supérieur aux limites recommandées par la directive européenne 2004/40/CE.Par contre, les mesures effectuées aux postes de travail de machines neuves équipées d'un dispositif appelé "patin de masse" ont montré que le niveau d'exposition des opérateurs se situait en dessous des valeurs limites préconisées. Un dispositif analogue a été installé sur des machines anciennes en cours de rénovation.L'objectif de cet article est de préciser les conditions à remplir pour obtenir avec un "patin de masse" une performance de réduction du champ électrique acceptable quelles que soient les conditions d'utilisation de la soudeuse."