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PubMed2001

Welding and joining techniques.

There is a welding solution for most applications. As products must meet more stringent requirements or require more flexible processes to aid design or reduce cost, further improvements or totally new processes are likely to be developed. Quality control aspects are also becoming more important to meet regulation, and monitoring and control of welding processes and the standardised testing of joints will meet some if not all of these requirements.

Equipment and Supplies↗
PubMed2002

[Characteristics of combined effect of thermal and welding aerosol exposure].

While studying a concurrent exposure to thermal loads and welding aerosols (WA) it has been ascertained that in inhalational exposure of the body to WA under conditions of simultaneous exposure of animals to a high temperature of the air environment the total pathogenic effect tends to be higher and higher. It is suggested that in a concomitant exposure to the above factors WA might lower bodily resistance to the thermal load. The above factors produce summation type harmful effects which have clearly a dose-dependent character. Studies on the occupational environment of workers engaged in welding involving heating suggested to us that it is those WA containing harmful substances of I and II hazard class that is the leading adverse factor of the working environment, and also thermal loads as high as 8000-9000 wt/m2. A concurrent exposure to the above factors lays a stress on the thermoregulatory function of the organism, and is resultant in the development of autoimmune processes and in premature aging of workers.

Aerosols↗
PubMed2002

Welding with lasers.

A laser welding process has been developed that offers the advantages of conventional laser welding without the use of opaque materials or the addition of unwanted colour.

Humans↗
PubMed2003

Health risk of occupational exposure in welding processes II. Immunological effects.

Many of epidemiological studies have certified the relationship between welding and various forms of health damages. In our study we performed an immunological research within a group of twenty men, working in the risky environment of manufacturing of stainless steel constructions (11 welders and 9 grinders, average age was 31 years, 55% of smokers, average time period in welding occupational exposure was 8 years). The exposed group of men was compared with a group of healthy blood donors, marked as the control group (people with various types of employment, living in same locality as a people from exposed group). People within the control group were not occupationally exposed to harmful chemical compounds (from 30 to 100 men were chosen for the individual immune parameters, average age of the whole group was 38 years, 40% of smokers). When compared with the control group, the exposed group of welders and grinders showed higher level of C3 complement (p < 0.001), orosomucoid (p < 0.05), beta-2-microglobulin (p < 0.001), neopterin (p < 0.001) and all fagocytic cells (p < 0.001). On the contrary, in the group of exposed people decreased values of IgA (p < 0.001), IgG (p < 0.001), IgM (p < 0.001), transferin (p < 0.001), alpha-1-antitrypsin (p < 0.001), alpha-2-macroglobulin (p < 0.001), haptoglobulin (p < 0.001) and ceruloplasmin (p < 0.05) were found. Some of these changes were characteristic for the exposed group. They could be considered as precursors of biological markers of effect for given type of exposure.

Acute-Phase Proteins↗
PubMed2003

Techniques for laser welding polymeric devices.

Recent advances in laser techniques mean that lasers are now being considered as an alternative to vibration, ultrasonic, dielectric, hot plate or hot bar welding, and adhesive bonding of plastics. The techniques required to put laser welding methods into practice are described for medical devices, tubular systems, films and synthetic fabrics.

Biocompatible Materials↗
PubMedDate not supplied

Proposal of a dose-response relationship between aluminium welding fume exposure and effect on the central nervous system.

Exposure to high levels of aluminium can affect the human central nervous system. Abnormalities of psychomotor function have been observed among haemodialysis patients with mean aluminium concentrations in serum of about 60 micrograms/l. According to our own data this corresponds to a urinary level of about 330 micrograms Al/l in aluminium-exposed welders without kidney failure. This post-shift urinary level of aluminium is estimated to be attained after 40 years of exposure to a welding fumes at an environmental concentration of approximately 1.6 mg/m3 of aluminium. An increased prevalence of effects on the nervous system was observed among welders exposed to aluminium fumes for more than 13 years. This finding supports the concept of cumulative toxicity due to aluminium exposure. On the basis of these observation, we suggest that the level of aluminium in welding fumes should not exceed 1 mg/m3.

Air Pollutants, Occupational↗
PubMed2006

[Application of the laser welding to preventing the break of the base plate caused by the increase of magnetic attachments].

OBJECTIVE: This study was intended to design a kind of resisting part dint of device in order to preventing the base plate break while being subjected to the dint when partial base plate dint concentrates because of the increase of the magnetic attachment to the original movable artificial teeth. METHODS: Ten patients who should increase magnetic attachment was adopted in the study, and we increased a kind of new designed partial cast base plate on the original base plate using laser welding technique, then designed magnetic attachment and artificial teeth. RESULTS: None of ten sufferers appeared the phenomenon of the break of the base plate. CONCLUSION: The application of the laser welding technique can prevent the break of the base plate when partial dint increase because of the increase of the magnetic attachments.

Dental Soldering↗
PubMed1991

Exposure to fumes in typical New Zealand welding operations.

Sixteen welders, welding under typical New Zealand conditions, had ambient air within their welding helmets sampled and analysed for ozone, nitrogen oxides, fluoride, carbon monoxide, aluminium, chromium, iron, nickel, zinc and total dust. Postshift urinary metals were also analysed, and a respiratory questionnaire completed for each welder. Levels above the New Zealand Workplace Exposure Standard (WES) were found for nitrogen dioxide in four welders (two TIG, one MMA and one plasma cutter), and for total chromium in one plasma cutter, who also had a nickel level of 24% of the WES. Dust levels were highest in the plasma cutters, with one reaching 8.67 mg/m3 (WES = 5 mg/m3). Urinary levels however did not indicate excessive short or long term uptake. Where efficient fume extraction was in use, levels of air contaminants were lower than with natural ventilation. Respiratory symptoms were reported by 67% of welders, 38% meeting criteria for chronic bronchitis (relative risk = 2.0). Smoking welders reported more symptoms than nonsmoking welders.

Adult↗
PubMed1990

[Effects of welding dust on morphology of the bronchopulmonary system and heart in experimental animals].

A comparative study was made of the action of 5 intratracheally introduced dusts (of manganese, silicon, potassium, natrium, calcium, fluorine, and iron) on the cardio-respiratory system. A more marked biologic activity of the hard component of welding aerosols with a high content of fluorine, potassium and soluble manganese compounds was established. This was proved by structural damages, such as atelectasis, emphysema, bronchiectasis in the lungs, dystrophic developments in the contractual myocardium, a sharp decrease in the luminescent intensity of the adrenergic terminals in the myocardium. All the welding dust samples did not display a fibrogenous activity in any degree.

Aerosols↗
PubMed1989

[The solubility of welding dusts and their cytotoxicity].

It was established as a result of cytotoxicity studies of 15 welding dusts of different compositions in experiments on embryonal fibroblast cell cultures that the biologic activity of these substances depends on the solubility in growth media of their major components: alkaline and alkaline earth metals, iron, cremnium and, to a vast degree, that of the manganese. Conclusion has been made that a comparative assessment of welding dusts' biological activity on cell cultures should involve the kinetic parameters of their solubility in growth and supportive media, and the duration of the substances' affecting the cell cultures should be long enough to reveal the combined action of its major ingredients.

Animals↗
PubMed1989

[Carcinogenic activity of nickel-containing welding aerosols in relation to their copper and manganese content].

Chronic experiments on animals showed that aerosols formed during cast iron welding and facing due to the use of electrode nickel-based materials could produce blastomogenic effect that was mostly caused by the presence of copper-and manganese-containing aerosols in the particles of the solid component. Morphologic inhomogeneity of the particles of the solid component, qualitative composition and solubility of the compounds spatially arranged in the surface layer were of great importance for their carcinogenic and toxic effect. The capacity of copper- and manganese-containing compounds to suppress nickel carcinogenic effect should be taken into account when developing welding and facing materials with better hygienic characteristics.

Air Pollutants↗
PubMed1989

[Effect of welding arcs on the eyes of patients with contact lenses (literature study)].

Two accidents had been reported from abroad, within which contact lense users grew blind after staying quite near at electrical arcs. It is supposed that the contact lenses had been "welded" with the cornea by influence of the electromagnetic radiation. Removal of lenses shall have caused the cornea "ablation" and thus the subjects permanent blindness. Nilsson et al. (1, 2, 5) performed intensive animal tests which proved, that contact lenses get hot in special spectral ranges thus underlying a certain drying up. The "welding" between contact lenses and the cornea could not be confirmed by test animals, but partial glueing of contact lenses and cornea and surface lesions of the epithelium as well in some cases. Hüer and Conrads (3, 4) experimenting on enucleated pigs' eyes, reported on similar results.

Blindness↗
PubMed1988

Magnetic field effects on dental amalgam in divers welding and cutting electrically underwater.

Divers have for some years been complaining about a metallic taste in the mouth while electrically welding and cutting underwater. This paper reports on results from an assessment of this problem. It was hypothesized that the magnetic fields arising from the welding or cutting current could correlate with the reported symptoms. The intraoral magnetic flux density was calculated to 1.15 mT, at 650 ADC, in a normal cutting situation. This was verified in vivo. This magnetic field was shown to contain an AC component that is a candidate for inducing secondary currents in the oral tissues and restorative materials. Five submerged divers exposed to a magnetic field of 0.35 mT did not report any metallic taste. Magnetophosphenes were reported by 1 diver. (Magnetophosphenes are luminous impressions due to excitement of the retina by a magnetic field in addition to or in place of impingement of light rays.) Only a slight shielding effect to magnetic fields was observed due to a copper-brass helmet. An in vitro model for exposure of dental amalgams to magnetic fields was designed. Recommendations for decreasing the magnetic field surrounding the diver in practical work is given.

Adult↗
PubMed1978

[Risk of absorption of fluoride in electrode arc welding].

The AA. in order to investigate the risk of fluoride absorption examined two factories in which arc-welding electrodes were used. They measured: a) fluoride content in two most used electrodes; b) airborne fluoride concentrations and dustness in the presumed respiratory area of welders with or without fume and dust capture devices; d) airborne fluoride concentrations and dustness three meters away from the welding place during unprotected work with basic electrodes; e) concentrations of fluoride in urine during a workweek in welders (n = 63) and in a control group (n. = 25). The AA. conclude that, in spite of the high teoretical risk of breathing fluoride, the intake of this compound is very low if welders are protected by easy devices.

Air Pollutants↗
PubMed1993

Intra-oral welding of implants for an immediate load with overdentures.

Different clinical applications of the Hruska intra-oral welding machine have been described in previous articles (Hruska, 1986, 1987, 1988, 1989a,b). These applications were related to over 100 cases of the use of non-submergible implants. This paper will describe a revised application of this machine as used with the currently popular multiform submergible implants widely used in the United States. The intra-oral welding is performed immediately after suture placement, with one or more connecting titanium wires serving as the splinting medium. This permits the patient to leave the office with a stable and retentive overdenture resting securely on the newly created splint performed the same day of surgery. This avoids the potentially troublesome problem of allowing the overdenture to be supported by the recently altered soft tissues. In addition, the patient otherwise would not have the use of a denture during the bone-healing period, which creates an alteration in psychological as well as physiological status. The disadvantages of immediate loading are counteracted by the splinting and load-sharing. This encourages the bone around the implants to reorganize and remodel according to Wolff's law, as demonstrated by De Angelis (1970) and Dalin and Olsson (1974). Different studies (Sutter et al., 1983a,b; Schroeder, 1985; Jennings, 1991) have shown that the ankylotic connection between one-stage titanium ITI implants and bone (so-called osseointegration) occurs and is maintained under load.

Dental Implantation, Endosseous↗
PubMedDate not supplied

Multiple exposure to metals in eight types of welding.

This article evaluates multiple exposures to metals in different types of metal welding such as manual metal arc for mild and stainless steel, continuous wire, submerged arc, laser and brazing. Environmental monitoring was carried out in eight different occupational situations and the inductively coupled plasma mass spectrometry technique was adopted in order to characterize exposure to several elements simultaneously and with high accuracy. The results showed that up to 23 elements could be measured. The highest concentrations were found for Al, Mn, Fr, Ni, Cr, Cu and Zn. For some elements such as In, Nd, I, Rb the concentrations were very low. A qualitative and quantitative variation in fume composition was observed at a certain distance from the welding point, which should be to taken into account when evaluating indirect exposures. It would also be possible, with this technique, to identify specific elements in the mixture which could also be measured in biological fluids.

Air Pollutants, Occupational↗
PubMed1997

[Sidero-fibrosis of the lungs after decades of arc welding].

The case of a patient is described who suffered from pulmonary siderofibrosis, histologically confirmed as a long-term cause of arc welding for several decades. In spite of this, there was no severe alteration of lung function. Pulmonary siderosis in welders was considered to be a benign pneumoconiosis. However, in recent years it has been noticed that siderosis is accompanied by disorders of pulmonary function, depending in particular on the quality of the working place, technology of welding, and duration of the exposition. Especially in smaller workshops without medical service and regular control of the craftsmen, unfavourable working conditions are frequent.

Biopsy↗
PubMed1997

[A preliminary study on p53 gene in lung cancer tissues of workers exposed to silica and welding fumes].

Mutations of suppressor gene p53 was studied in 36 cases of silica related lung cancer and 6 cases of welding fume related lung cancer with immunohistochemical and PCR-SSCP methods. Cancer tissues were embedded in paraffin and stored for 13.4 years in average. Results revealed that there was abnormal mobility shift of electrophoresis in 18 cases with 20 point mutations of 42 specimens tested, accounted for 42.9%, and 50% (10/20) of the mutations were clustered in exon 8. This finding differed from mutational spectrum of gene in non-occupational lung cancer, in which mutation frequency of exon 8 ranged from 17.5% to 23.5%. Gene mutation frequency in varied pathological categories of pneumoconiosis related lung cancer also differed from that in common lung cancer. In the latter, the highest one was in small cell lung cancer (70%) and the lowest in adenocarcinoma (33%), but in the former, the highest in adenocarcinoma (53.9%) and the lowest in small cell lung cancer (30.8%). Immunohistochemical observations also showed a very high prevalence of p53 gene mutation expression (46.9%). Sequencing, which was determined in two cases of this study, revealed that two point mutations all occurred in non-hotspot codon 144 of p53 gene. Difference in gene mutation spectrum suggests that there exist specific carcinogens and carcinogenesis in silica and welding fume related lung cancer.

Adenocarcinoma↗