Argon arc welding is relatively more harmful than electrode arc welding, but not so much that it is intimidating. The infrared radiation is about 1-1.5 times that of ordinary electrode arc welding, and the ultraviolet radiation produced by the argon arc welding arc is about 1.5 times. It is 5 to 20 times that of electrode arc welding.
When welding in a limited space, the ozone concentration can reach dangerous levels. During the welding process, harmful gases such as carbon dioxide and carbon monoxide as well as metal dust will also be produced, which will cause certain harm to the welder.
Therefore, we should take good protection during the welding process, choose electrode materials, and try to use low radioactivity cerium and tungsten. When grinding electrodes, wear masks and gloves and wash your hands after work to minimize risk.
Dangers of high frequency electromagnetic fields
Welding generally uses a high-frequency oscillator with a frequency of 200 to 500 kHz, a voltage of 2500 to 3500 V, and an electric field strength of 140 to 190 V/m. When the arc is struck, the intensity of the high-frequency electromagnetic field generated is between 60 and 110V/m, several times higher than the reference health standard (20V/m).
In fusionless electrode argon arc welding and plasma arc welding, high-frequency oscillators are commonly used to stimulate the arc. Some AC argon arc welding machines also use high-frequency oscillators to stabilize the arc. Under the action of high-frequency electromagnetic fields, the human body can absorb a certain amount of radiation energy and produce biological effects, mainly thermal. The intensity of high-frequency electromagnetic fields is affected by many factors, such as distance. The closer the oscillator and the oscillation loop are, the higher the field intensity will be, and vice versa.
In addition, this is linked to the degree of shielding of the high frequency part. The human body will produce biological effects under the action of high-frequency electromagnetic fields. Long-term exposure of welders to high-frequency electromagnetic fields can cause autonomic nerve dysfunction and neurasthenia. Symptoms include general malaise, dizziness, headache, fatigue, loss of appetite, insomnia and low blood pressure.
If a high frequency oscillator is used only to induce an arc, the impact will be small due to the short time. If arcing occurs frequently or the high frequency oscillator is continuously used as an arc stabilizing device during the welding process, the high value. High frequency electromagnetic field can become one of the harmful factors.
radioactive risks
Thoriated tungsten used in argon arc welding contains 1% to 1.2% thorium oxide. Thorium is a radioactive element that emits three types of rays: α, β and γ. During the welding process and contact with thoriated tungsten rods, radiation effects may occur. Through extensive investigations, it was found that only 100-200 mg of thoriated tungsten rods are consumed every day and the radiation dose is extremely low and has little impact on the human body. However, when welding in containers, ventilation is poor and the radioactive particles present in the smoke can exceed health standards;
Second, when tungsten and thorium rods are ground and stored, the concentration of radioactive aerosols and radioactive dust can reach or even exceed health standards. Radioactive substances invading the body can cause chronic radiological diseases and form internal exposure, which are mainly manifested by a weakening of the general functional state. Symptoms such as obvious weakness and weakness, significantly reduced resistance to infectious diseases, and weight loss may be observed.
Baidu Encyclopedia: Radioactive aerosols are solid or liquid particles containing radionuclides suspended in air or other gases. Dispersion system formed of solid or liquid radioactive particles suspended in air or in a gaseous medium. The fundamental characteristics of aerosols are unstable. Particles smaller than 0.1 microns undergo Brownian motion in the gas and do not settle under gravity; particles between 1 and 10 microns settle slowly and remain suspended in the air for a long time. Radioactive aerosols have high ionization effects, low concentrations, and easily charged particles (produced by radioactive decay). Radioactive aerosols pose a major threat causing internal human exposure.
Risks associated with a powerful arc light
Welding arc radiation mainly includes visible light, infrared rays and ultraviolet rays. They act on the human body and are absorbed by human tissues, causing thermal, photochemical or ionization effects on the tissues, thereby causing damage to human tissues.
The brightness of visible light is approximately 10,000 times greater than the normal brightness of the naked eye. When visible light radiates into human eyes, it causes pain and blurs vision and the person loses the ability to do so. work in a short period of time.
The main harm of infrared rays for the human body is the thermal effect on tissues. During the welding process, if the eyes are exposed to strong infrared radiation, they will immediately experience severe burning and pain, as well as flash hallucinations. Long-term exposure can cause infrared cataracts, vision loss, and in severe cases, blindness.
Ultraviolet (UV) radiation, also known as ultraviolet radiation, refers to electromagnetic waves with a wavelength between 100 and 400 nm. An appropriate amount of ultraviolet radiation can have beneficial effects on the human body, but excessive exposure may cause adverse effects on the human body (such as ultraviolet radiation from welding). The damage caused by ultraviolet rays to the human body is mainly due to photochemical effects, causing damage to human skin and eyes. Once the skin is exposed to strong ultraviolet radiation, it can cause dermatitis, diffuse erythema, sometimes small blisters, exudate, burning and itching;
When the effect is strong, it is accompanied by systemic symptoms: headache, dizziness, fatigue, nervous excitement, fever, insomnia, etc. Excessive exposure to ultraviolet rays of human eyes can cause acute cornea and ocular conjunctivitis, i.e. electrophotophthalmia. Symptoms are high blindness in both eyes, tearing, foreign body sensation, tingling, redness and swelling of the eyelids, spasms, accompanied by headache and blurred vision.
The dangers of welding fumes
A large amount of metal welding dust will be produced during the welding process. The diameter of the metal powder produced by welding is very small, which is easier to inhale into the lungs. Due to its small diameter, it is difficult to evacuate. of the body, therefore pathological changes occur. The higher the welding current intensity, the higher the dust concentration. When the concentration of welding dust is high and there are no corresponding dust removal measures, long-term exposure to welding dust may cause occupational diseases such as welder’s pneumoconiosis, manganese poisoning and metal fever.
Reproductive toxicity. In the past 10 years, research on the reproductive toxicity of electric welding operations has been carried out at home and abroad, mainly focusing on the sperm quality of male workers, reproductive outcomes and mechanisms of damage to female workers. Research shows that female welders experience increased menstrual flow, shortened menstrual periods, prolonged menstrual periods, increased leukorrhea, spontaneous abortions, premature births, and dysmenorrhea compared to the control group. The semen of manganese-poisoned male workers had a uniform gray-white appearance, normal pH, and the average liquefaction time was longer than that of the control group.
The test results showed that the average ejaculate volume, total sperm count, sperm survival rate and motile sperm rate of the manganese poisoned male workers were all lower than those of the control group. The sperm deformation rate of male workers with manganese poisoning was significantly higher. than that of the control group. It is believed that metallic manganese can affect the male spermatogenesis system, have a direct toxic effect on sperm development and kill sperm, thereby causing changes in male sperm quality. There are also reports abroad that welders’ sex hormone secretion changes and sperm quality decreases, but this has no effect on the sex ratio of their offspring.
Dangers of harmful gases
Under the action of high temperatures and strong ultraviolet rays of the welding arc, various harmful gases are formed around the arc, including ozone, nitrogen oxides, carbon monoxide and carbon dioxide. hydrogen. Ozone is a light blue irritant and toxic gas. When the concentration is high, it emits a fishy odor; high concentration ozone also has a slightly sour odor.
The main danger of ozone for the human body is its strong irritating effect on the respiratory tract and lungs. It often causes cough, chest tightness, loss of appetite, fatigue, dizziness, body pain, etc. In severe cases, it can also cause bronchitis and pulmonary edema.
Nitrogen oxides are irritating and toxic gases. Nitrogen dioxide is reddish brown in color and has a distinctive odor. The main danger of nitrogen oxides for the human body is its stimulating effect on lung tissue. After being inhaled into the respiratory tract, it gradually reacts with water in the alveoli to form nitric acid and nitrous acid, which strongly stimulate and corrode lung tissue, causing poisoning.
The main symptom of chronic poisoning is neurasthenia, such as insomnia, headaches, loss of appetite and weight loss. High concentrations of nitrogen oxides can cause acute poisoning. In case of mild poisoning, only acute bronchitis will occur; in severe poisoning, it can cause symptoms such as severe cough, difficulty breathing, collapse and general weakness.
The effect of nitrogen oxides on the human body is also reversible, as the time off work increases, its harmful effects are gradually reduced or eliminated. When tungsten-argon arc welding, if ventilation measures are not taken, the concentration often exceeds sanitary standards by more than ten times or even dozens of times. The hygienic standard for nitrogen oxides (converted to nitrogen dioxide) stipulated in our country is 5 mg/m3. During the welding process, ozone and nitrogen oxides are usually present together, making them more toxic. In general, the simultaneous presence of two toxic gases is 15 to 20 times more harmful than a single toxic gas.
protective measures
1) Ventilation measures
The argon arc welding site must have good ventilation devices to evacuate harmful gases and fumes. In addition to plant ventilation, multiple axial fans can be installed to exhaust air in high welding workload areas and on concentrated welding machines. Additionally, local ventilation measures can be used to eliminate harmful gases around the arc, such as open arc fume extraction hoods, fume exhaust welding guns, small lightweight fans, etc. .
2) Radiation protection measures
Use cerium tungsten electrodes with an extremely low radiation dose whenever possible. When processing thorium tungsten and cerium tungsten electrodes, sealed or vented grinding wheels should be used for grinding. Operators should wear masks, gloves and other personal protective equipment and wash their hands and faces after treatment. Thorium tungsten electrodes and cerium tungsten electrodes should be stored in aluminum boxes.
3) Protective measures against high frequencies
In order to prevent and weaken the influence of high-frequency electromagnetic fields, the measures taken are as follows: 1) The workpiece is well grounded, and the welding gun cable and ground wire should be protected by braided metal wires. 2) The frequency is appropriate; reduced; 3) Try not to use high frequency oscillators because the arc stabilizing device reduces the action time of high frequency electricity.
4) Other personal protection measures
During argon arc welding, due to the strong effects of ozone and ultraviolet rays, it is advisable to wear work clothing that is not made of cotton (such as acid-resistant fabric, tussah silk, etc.). When welding in a container and local ventilation cannot be used, personal protective measures such as supplied air helmets, supplied air masks or respirators may be used.
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