Welding Units Research Articles

Respiratory symptoms and spirometric abnormalities among welders in the welding workplace of the Indian unorganized sector.

Welding is one of the most hazardous professions across the globe. Several risk factors are associated with Indian unorganized welding units such as welding gases, fumes and dust particles resulting in various respiratory health problems. The objective of the present study is to examine the prevalence of respiratory symptoms, their associated factors and lung function impairment amongst the welders of the unorganized sector in India. A cross-sectional study was conducted across 283 welders of age group 18-55 years from Punjab, India who responded to the interviewer-administrated respiratory symptoms questionnaire. Also, the lung function parameters of 50 male welders (exposed group) and 50 male non-welders (control group) working in the same environment were evaluated. The prevalence of respiratory symptoms such as chronic cough (38.86%), phlegm (38.86%), shortness of breath (33.56%), wheezing (32.15%), chest tightness (36.40%,) and sputum (34.27%) was reported by the welders. The observed mean values of forced vital capacity (FVC), forced expiratory volume in 1s (FEV1) and FEV1/FVC ratio of welders were (3.37±0.175), (2.59±0.16) and (76.63±6.16) respectively and that of non-welders were (3.70±0.15), (3.05±0.25) and (82.49±7.62) respectively. The welders were found to be at significant risk of developing pulmonary diseases. Long working hours, low level of education, hazardous working conditions, lack of implementation of safety laws make welders more vulnerable to health risks. The welders of Indian unorganized sector work without any technical training related to welding and safety. Proper orientation sessions about the workplace hazards and to maintain hygiene at their workplace should be organized. Welders must be provided with Personal Protective Equipment (PPE). Welders should take proper health check-up and medication to sustain healthiness.

A Welding Unit Partition Method of Complex Weld Parts

Welding modularization can make the process planning and manufacturing of complex welding products easier, convenient and synergy. The appropriate units partition is critical for welding modularization. This paper proposes a method of welding units partition for complex welding parts. Firstly, the basic parts and sub parts of welding units are defined. Then, the basic parts are evaluated by using the fuzzy analytical hierarchy process (FAHP) method and the number of basic parts is determined by the improved units partition formula. Furthermore, the welding units are classified by the minimum spanning tree (MST) algorithm and the interference matrix is used to evaluate partition results. Finally, a rear sub frame of automobile is taken as an example to validate this method.

A Report Based on Analysis of Posture and Occupational Health of Welders in Different Welding Units

Analysis of work posture of workers is an effective research area in manufacturing sector in India. Manufacturing plays a significant role to develop a country. Lots of human involvements are required to successfully execute the various operations involved in this area. Long manual working hours with traditionally designed tools and un-ergonomic work posture can cause musculoskeletal disorders and other occupational health problems among welders. Prolonged working hours exceed the physical capacity of the workers that causes' discomfort, physical fatigue, joints pain, swelling, strain, sprain of ligaments and soft tissues. Work related musculoskeletal disorders (WRMSD) in the form of repetitive motion injuries, cumulative trauma disorders, body fatigue and strain injuries are very common health problems of workers of different small & medium scale welding units in our country. The productivity and cost benefits of welding units are highly related with the physical comfort of the welders. The data of musculoskeletal disorder of workers of welding units was collected evaluated and validated by using RULA, OWAS and Discomfort Questionnaire and a design solution suggested.

Occupational noise-induced hearing loss in auto part factory workers in welding units in Thailand.

Most workers in auto part factories in Thailand are usually exposed to excessive noise in their workplace. This study aimed to assess the level of occupational noise-induced hearing loss and investigate risk factors causing hearing loss in auto part factory workers in the welding units in Thailand. This was a cross-sectional study. One hundred eighty subjects were recruited from 356 workers in the welding unit of three factories. Sixty eligible subjects in each factory were selected by systemic random sampling. The subjects were interviewed using a face-to-face questionnaire. Noise exposure levels and audiograms were measured by a noise dosimeter and an audiometer, respectively. The findings confirmed that noise exposure levels of 86-90 dB (A) and exceeding 90 dB (A) significantly increased the risk of hearing loss in either ear. A noise exposure level exceeding 90 dB (A) significantly increased the prevalence of hearing loss in both ears. Regarding, a 10-pack-year smoking history increased the prevalence of hearing loss in either ear or both ears. In addition, subjects with employment duration exceeding 10 years significantly developed hearing loss in either ear. The engineering control or personal control by wearing hearing protection device should be used to decrease noise exposure levels lower than 85 dB (A) for 8 h. Moreover, if the exposure level reaches 85 dB (A) for 8 h, the employer needs to implement a hearing conservation program in the workplace.

Occupational safety measures and morbidity among welders in Vellore, Southern India.

Welders in the unorganized occupational sector in the economically developing world are exposed to respiratory, skin, eye, ear, and neurological problems exacerbated by non-usage of personal protective equipment (PPE). To study the frequency of health problems and the usage of PPE among welders in unorganized welding units in Vellore, India. A cross-sectional survey was conducted among 150 welders to determine the frequency of skin, ear, eye, and respiratory morbidity and the usage of PPE. A group of 150 non-welders were chosen for comparison. Significant differences in the frequency of skin burns, redness, hyper pigmentation, itching, eye injuries, and sensorineural deafness were observed among the welders and non-welders (P < 0.001). Hypertension was noted in 12.6% of the welders as compared to 0.7% among the non-welders. None of the welders used appropriate PPE. For welders, low educational attainment was associated with an increased risk of eye injury (P < 0.05, OR = 0.29). There was also a significant difference between sensorineural deafness and a welder having less than 10 years of welding work experience (P < 0.001, OR = 18.18) which could probably be accounted for by the healthy worker effect. Welders in this sample experienced a significant skin, eye, and ear morbidity accentuated by the non-usage of PPE. All worked without formal training and were unaware of the safe working guidelines that exist, but are not implemented for the welders in India.

Assessment of the effect of welding fumes on welders’ cognitive failure and health-related quality of life

Introduction. This study examined whether cognitive symptoms and health-related quality of life can be affected by welding fume exposure. Method. Participants consisted of welders (n = 40) and welder assistants (n = 25) from welding units as the exposed group, and office workers (n = 44) as the non-exposed group. All participants were studied using ambient air monitoring and two types of questionnaires: the Cognitive Failures Questionnaire (CFQ) and the 36-item Short Form Health Survey (SF-36). Results. Welders and welder assistants were exposed to higher concentrations of all airborne metals than office employees, except for aluminum and chromium (p < 0.05). Mean (95% confidence interval) CFQ score was higher in welders (26.42 (12.74)) compared with welder assistants (22.68 (14.37)) and the non-exposed group (21.38 (8.75)), although these differences were not statistically significant. Mean total score of the SF-36 significantly differed among the three groups (p < 0.05) and welders had the lowest score (M (SD) = 54.84 (17.88)). The relationships between total CFQ score and the measured concentration of nickel at peak work rate was significant for welders. Conclusion. Cognitive symptoms and health-related quality of life were not related to the measures of welding fume exposure and further research should be performed to find other influencing factors.

Управление эффективностью технологического процесса изготовления клапана на базе оценки точности статистическими методами

Results of research and control of efficiency of process of production of technologically difficult, high-precision valves are given. Strict requirements are imposed to these products, as to the products applied in oil and gas extraction complexes, repair and welding units in researches of wells and units on the basis of all-wheel drive wheel and caterpillar chassis. Results of identification of critical technological operations of production of valves are given. Results of an assessment of technological accuracy of processes by statistical methods: control leaves, histograms, Isikava's charts, Pareto's charts, ABC analysis are reflected. Analysis of accuracy of operations by method of dot charts, calculation of statistical parameters: index of reproducibility, indicator of working capacity, indicator of centrality, level of deficiency allowed to reduce deficiency level, to increase production accuracy, to lower a roughness of the processed surface, to reduce operational expenses at finishing grinding. Process “A periodic assessment of accuracy of technological operations” is developed (described, visualized and estimated), the standard of the organization on this process is created and introduced. Results of the executed research project allow to support constantly requirements of technological process of production of valves in the condition, which guarantees production of the established level of quality.

Modern principles for construction of power sources for electron-beam welding units

Modern requirements for power sources of welding electron guns are formulated. The electron-gun parameters are analyzed as the power source load, and main trends in electrical equipment for electron-beam welding are revealed. The modern principles for construction of power sources for electron-beam welding units are considered using the example of two schematic diagrams.

Contrasting styles of welding observed in the proximal Askja 1875 eruption deposits I: Regional welding

Welded fall deposits on the northern caldera rim at Askja volcano are associated with the Plinian phase of the 1875 eruption. Two welding units occur within the proximal Plinian fall centered on stratigraphic sub-units which, where non-welded, are poorly sorted and ash-rich with high abundances of fluidal and needle-like ash particles. Welding has formed due to two discrete processes; a) the sintering of hot ash and lapilli which forms the two distinct units that are laterally continuous on distance scales of tens of meters (termed ‘regional welding’), and b) creation of welding halos enclosing large, dense, discrete, non- to poorly vesicular spatter bombs that are up to 9 m in diameter (termed ‘local welding’). This paper is concerned with the nature of regional welding and the companion paper (this issue) focuses on the phenomenon of local welding. Three case studies documenting the range of welding patterns observed in regional welding are presented here. Vertical and lateral profiles of welding intensity, together with the deposit characteristics reveal that welding could only occur when the accumulation rates were sufficient and that grain size and thickness are second order factors facilitating welding. Rapid and reversible shifts in both thickness and welding grade are observed on a ~ 10 m scale laterally along the caldera rim suggesting considerable unsteadiness of the transport regime, which promoted localized fluctuations of the accumulation rate. The welded deposits prompt re-examination of both the dynamics of the Plinian phase of the 1875 eruption and the distribution of source vents. The dispersal of the welding units is not compatible with deposition from the full height of the Plinian plume. Similarly to the ultra-proximal deposits of Novarupta or Tarawera, these clasts probably fell from heights of hundreds of meters to < 4 km, retaining sufficient heat to weld after deposition. The E–W elongated distribution of the welded units is also not compatible with a single source vent, and favors several vents that were in a fountaining phase, and located adjacent to the northern rim.

Contrasting styles of welding observed in the proximal Askja 1875 eruption deposits II: Local welding

As an alternative to classical welding models of fall deposits due to the progressive accumulation of hot tephra which then weld, we describe here welded deposits on the northern 1875 caldera rim of Askja volcano that have welded due to the influence of hot, discrete spatter bombs impacting into and supplying heat to a halo of surrounding tephra. This style of welding we term ‘local welding’ in contrast to ‘regional welding’ which is described elsewhere [Carey, R.J., Houghton, B.F., Thordarson, T., 2008. Contrasting styles of welding observed in the proximal Askja 1875 eruption deposits I: Regional welding. J. Volcanol. Geotherm. Res. 171, 1–19. doi:10.1016/j.jvolgeores.2007.11.020]. Locally welded deposits are associated with the rhyolitic Plinian phase of the 1875 eruption of Askja volcano. Two distinct welding units (W1 and W2) are interbedded with Plinian fall on the northern caldera rim, and grade outwards to weakly dispersed non-welded fall. Spatter bombs are found in both welding units but vary in their characteristic sizes and internal features. In the W1 unit simple bombs with homogeneous internal characteristics up to ∼ 60 cm in diameter are found. In the W2 unit, large discrete spatter bombs with complex internal features range up to 9 m in diameter. We describe here two case studies showing the effects of a) single small spatter bombs; b) multiple small spatter bombs and c) large discrete spatter bombs varying in size. Vertical and lateral profiles through welding zones reveal that the primary controls on local welding are the availability of supplied or added heat and the loading capacity of the spatter bomb. Local welding grades are much higher than that of regional welding, as the combined effects of heat, compaction and insulation can provide suitable conditions which lead to dense welding and, proximal to the spatter bomb, rheomorphic flowage. If heating and loading exceed the critical requirement for welding, porosity loss via matrix welding and vesicle collapse occurs to a point where further strain must be accommodated as shearing and ductile flowage. The spatter bombs are found only within the weakly dispersed welding units and are the final erupted products of each fountaining phase. Their low viscosities are evident by their deformation on impact and fluidal forms, and hold some important clues to eruption dynamics in the shallow conduit and vent regions.

Toward a theory of governing equations of nonlinear thermoviscoelasticity for periodic deformation

The study of vibrations and vibrational heating of solids with amplitude-dependent characteristics is important for designing vibration-damping systems containing elements made of high-filler-content polymers [6, 12], metalwaveguides in ultrasonic welding units [i], etc. The most recent results obtained in this broad area at the juncture of physics and mechanics were generalized in the monographs [7-9]. The main tasks to be performed in the problem in question are: selection of governing equations, suitable formulation of the coupled thermoviscoelastic problem, development of methods of its numerical realization, and study of the therm0mechanical behavior of bodies. The present study is devoted to the first and part of the second questions, i.e., to analysis of different approaches to the construction of approximate governing equations of nonlinear viscoelastic bodies subjected to small periodic, deformations. i. Construction of the Governing Equations. Wewill study the structure of the governing equations of stable, nonlinear viscoelastic media, These equations describe the polyharmonic reaction to the stresses

Multitransformer welding presses

Users OF resistance welding equipment are finding “presswelding” to be ideally suited to many of their high-production applications. In its general concept, presswelding may be likened to present-day stamping-press practice; however, instead of forming or trimming, the weld press produces from 16 to 160 spot welds practically simultaneously on a given assembly. The welding press also differs from the usual stamping press in that the ram or movable platen is generally located in the lower part of the machine. This arrangement facilitates the location of the welding units and usually favors loading of the parts to be welded. Figure 1 shows three typical press types. The 4-post machine is used for large assemblies while the 2-post or open press is used for smaller operations.