Background: Hazardous chemical agents in the WELDING operation are a mixture of metal fumes and toxic gases, the inhalation of which causes adverse health effects among welders. The emission of gases in the workplace is a logical cause for concern regarding the potential development of respiratory disease. The aim of the present study was to determine the concentration values of gases discharged during arc WELDING and perform risk assessment through semi-quantitative chemical risk assessment (SQCRA) method.Materials and Methods: This cross-sectional study was conducted in an Iranian steel mill on the 3 PROCESSES of plasma arc WELDING (PAW), submerged arc WELDING (SAW), and gas tungsten arc WELDING (GTAW). Direct reading instruments were used for sampling of carbon dioxide (CO2), carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO2), and ozone (O3). SQCRA method was used for risk assessment of gases.Results: The concentrations of O3 (0.356 ppm), CO (41.642 ppm), NO (6.357 ppm), and NO2 (4.871 ppm) were found to exceed their threshold limit values (TLVs), while the concentrations of CO2 (3879.285 ppm) were below its TLV. The maximum exposure concentration of all gases, except CO2, was observed in SAW. SQCRA method showed that among the gases, the highest and least risk rating was related to ozone and nitrogen monoxide, respectively. The risk rating for CO2, CO, and NO2 was low, high, and very high, respectively.Conclusions: In this study, exposure values were higher than the threshold limit values-time weighted average (TLV-TWA) and the results of risk assessment showed that control engineering should be applied and the use of respiratory protective equipment (RPE) should be made mandatory for welders especially in SAW, PAW, and GTAW PROCESSES.

One of the interesting state-of-the-art approaches to WELDING is the process of friction stir WELDING (FSW). In comparison with the fusion PROCESSES, FSW is an advantageous method as it is suitable for the non-fusion weldable alloys and polymeric materials joining. Regarding the materials pure solid state joining, it also provides joints with less distortion and enhanced mechanical properties. In the present work, a three-dimensional (3D) model based on finite element analysis was applied to study the thermal history and thermomechanical procedure in friction stir WELDING of high density polyethylene plate. The technique includes the tool mechanical reaction and the weld material thermomechanical procedure. The considered heat source in the model, includes the friction among three items: the material, the probe and the shoulder. Finally, the model was validated by measuring actual temperatures near the weld nugget using thermocouples, and good agreement was obtained for studied materials and conditions.

The fumes and gases releasing from WELDING PROCESSES may seriously affect welders’ health compared to other hazardous agents arising from WELDING like, noise, and ultraviolet radiation. The present study was aimed to measure the exposure levels of welders to fumes and gases at seven of arc WELDING PROCESSES in a melting company. This descriptive-cross sectional study was carried out on several types of arc WELDING including TIG, GMAW, PAW، SAW, and MMAW in a melting industry. In order to measure the concentrations of WELDING fumes, NIOSH 7300 method was applied. Direct reading instruments were used for sampling of WELDING gases. The median concentration of all studied metals among different types of WELDING process were significantly different (P<0. 02). The median concentration of some released gases among different types of WELDING process were not significantly different (P >0. 05). The average exposure levels for metals of Cu (from TIG), Fe (from PAW and MMAW PROCESSES), Mn (from GMAW, MMAW PROCESSES), and Cr (from PAW and MMAW PROCESSES) were higher than Occupational Exposure Limit-Time Weighted Average. The finding showed that the nitrogen dioxide average concentrations and ozone gases were higher than the other gases. The welder’ s exposure levels to toxic metals and gases in some stations exceeded from recommended levels; so, it is necessary to apply the appropriate preventive methods like engineering control measures to effectively protect welders’ health.

In the present investigation, the effect of WELDING PROCESSES on the microstructure, crystallographic texture, mechanical properties, and anisotropy of weldment joints of a high strength low alloy steel (HSLA) was studied. The main goal of this research is to establish the relationship between microstructure, texture evolutions, and mechanical properties of the weldments. GTAW and SMAW WELDING PROCESSES were conducted, and macro texture of samples was investigated with the X-ray diffraction technique. Mechanical properties were evaluated by using the uniaxial tensile test in three directions of 0, 45, and 90°,to the weld line and a micro hardness test. Preferred orientation in the weldment develops in different WELDING PROCESSES based on the initial base metal texture. The texture of the base metal consisted of γ,-fiber, α,-fiber, G {110} <001>, and R-Cube {001} <110> main components that evolves during the WELDING PROCESSES. Weakening of the γ,-fiber texture component results in a significant reduction in the mechanical properties of the weldments. Moreover, the percentage of the γ,-fiber component in the GTAW sample is greater than the SMAW sample, which results in superior mechanical properties.

Background: WELDING is a common industrial process and is harmful to welders' health. Objective: To determine the effect of toxic gases and metal fumes produced during 3 WELDING PROCESSES on welders' incidence of respiratory symptoms and pulmonary function. Methods: This cross-sectional study was conducted in an Iranian shipbuilding industrial factory in 2018. Using the simple census method, 60 welders were selected as the exposed group. 45 staff members of the administrative unit were also recruited to be served as the control group. Welders' demographic data and respiratory complaints were collected employing a questionnaire. Fumes and gases produced were sampled from the welders' respiratory tract and analyzed by standard methods suggested by the National Institute of Occupational Safety and Health (NIOSH). Pulmonary function test was also performed for each participant. Results: The prevalence of respiratory symptoms in all welders was significantly (p<0. 05) higher than the control group. The mean FVC, FEV1 and FEV1/FVC measured in welders involved in all 3 PROCESSES were significantly lower than those recorded in the control group. The spirometry pattern in welders involved in flux cored arc WELDING and shielded metal arc WELDING was obstructive; that in those involved in gas metal arch WELDING was mixed (obstructive and restrictive pattern). Conclusion: Exposure to WELDING fumes and gases was associated with pulmonary function deterioration. Welders involved in gas metal arch WELDING had a higher prevalence of pulmonary disorders compared with those involved in gas metal arch WELDING and flux cored arc WELDING.

The effect of WELDING residual stresses that was created in thin infill plate of steel plate shear wall system during constructional PROCESSES was studied in this research. Residual stresses in a welded structure is the result of the non-uniform expansion and contraction and plastic deformation of the weld and surrounding base metal due to heating and cooling cycle, during WELDING process, this issue could affected SPSW`s behavior. In this research ABAQUS finite element software is utilized to simulation of WELDING process and steel plate shear wall behavior. Sequentially coupled thermo-elastic–plastic finite element computational procedure is developed to calculate temperature field and WELDING residual stresses in SPSW. The result shows that residual stresses created in infill plates of three story steel plate shear wall with rigid beam-column connection due to WELDING process makes yielding load, ultimate load, stiffness, ductility and energy absorption, decrease 1.4%, 1.26%, 7.6%, 7.3%, 3.4% respectively in model with residual stresses in comparison with model without residual stresses. Thus, the ignore of residual stresses effect due to WELDING in prospect of thin steel plate shear walls (SPSWs) behavior is negligible.

Background: Exposure to the evaporated gases during the WELDING process has short-or long-term effects on welders’ health. Assessment of the risk by identifying and determining the chemical risk rating might be a useful tool for the experts in industrial hygiene. Objectives: The present study aimed at evaluating the exposure of welders to WELDING gases in seven WELDING types in the Steel Industry. Methods: The present study was conducted in one of the factories of the steel industry in 2017. Seven types of WELDING were studied includingSMAW-E7018, SMAW-E730, MIG, MAG, PAW, SAW, and GTAW. Sampling from theNO, NO2, CO, CO2, andO3 was done via directreading instruments. To assess the health risk of exposure, the used approach was the one proposed by the division of occupational safety and health of the labor department of Singapore. Results: Findings of the present study revealed that the average range of welders’ exposure to NO, NO2, CO, CO2, and O3 gases in various WELDING PROCESSES was 30-50, 2456-5000, 2-12, 3. 5-6, and 0. 16-0. 5 parts per million (ppm). Maximum and minimum concentrations of exposure to each of the gases were observed in MIG and PAWWELDING PROCESSES, respectively. The results of risk assessment showed that ozone and nitrogen dioxide had a very high-risk rating and nitrogen monoxide had a rank of “ negligible” in all types of WELDING. Among the different types of WELDING, the most and the least risks of WELDING types were in MIG and PAW WELDING, respectively. Conclusions: MIG welders have a high occupational exposure to various types of WELDING gases. Use of control measures such as installing a local ventilation system, workplace air monitoring, implementing appropriate respiratory protection, and training the workers are recommended for safety of the welders.