Argon arc welding has a greater degree of damage compared to stick arc welding, but it is not a cause for alarm. The level of infrared radiation produced during argon arc welding is about 1 to 1.5 times higher than that of ordinary electrode arc welding, and the ultraviolet radiation generated is about 5 to 20 times higher.
In confined spaces, ozone concentration can reach dangerous levels during the welding process. In addition, harmful gases such as carbon dioxide, carbon monoxide and metal dust are produced, which can harm the welder.
Therefore, it is important to take the necessary precautions during the welding process, such as using protective equipment and selecting electrode materials with low radioactivity, such as cerium and tungsten. Additionally, wearing masks and gloves when sanding electrodes and washing your hands after work can help minimize risks.
High frequency electromagnetic field damage
The high-frequency oscillator is frequently used in welding, with a frequency ranging from 200 to 500 KHz, voltage from 2,500 to 3,500 volts and electric field strength from 140 to 190V/m. During arc lighting, the intensity of the high-frequency electromagnetic field generated is between 60 and 110 V/m, which is several times higher than the reference hygiene standard of 20 V/m.
In meltless electrode argon arc welding, plasma arc welding and cutting, high-frequency oscillator is often used to excite the arc, and some AC argon arc welding machines also use it to stabilize the arc. The human body absorbs part of the radiation energy and experiences biological effects, mainly thermal effects, under the action of the high-frequency electromagnetic field.
The intensity of the high-frequency electromagnetic field can vary based on factors such as distance; the closer the oscillator and the oscillation circuit, the greater the field strength. It also depends on the shielding of the high frequency component.
Prolonged exposure to a high-frequency electromagnetic field by a welder can cause autonomic nerve dysfunction and neurasthenia, resulting in symptoms such as general discomfort, dizziness, headache, fatigue, loss of appetite, insomnia, and low blood pressure.
Although the impact of using the high-frequency oscillator for arc formation is relatively small due to the short period of time, frequent or continuous use of the oscillator as an arc stabilizing device in the welding process may make the high-frequency electromagnetic field a harmful factor.
Radioactive hazard
Thorium tungsten, used in argon arc welding, contains 1% to 1.2% thorium oxide, which is a radioactive element that emits α, β, and γ rays. During welding and contact with thorium and tungsten rods, one may be exposed to radiation.
According to numerous investigations, the daily consumption of thorium tungsten rods is only 100 to 200 mg, and the resulting radiation dose is small and has little impact on the human body. However, if welding is carried out in a poorly ventilated container, the concentration of radioactive particles in the smoke may exceed hygiene standards. Furthermore, during the grinding of thorium tungsten rods and in thorium tungsten rod storage areas, the concentration of radioactive aerosols and dust may meet or exceed hygiene standards.
If radioactive substances enter the body, they can lead to chronic radioactive diseases and internal irradiation, causing symptoms such as weakened general functional status, obvious weakness, decreased resistance to infectious diseases, weight loss and others.
Encyclopedia:
Radioactive aerosols are particles, solid or liquid, containing radionuclides suspended in air or other gases. They are created by a dispersal system in which solid or liquid radioactive particles are suspended in air or other gases.
The defining characteristic of aerosols is their instability. Particles smaller than 0.1 microns move through the gas due to Brownian motion and do not settle due to gravity. Particles between 1 and 10 microns settle slowly and remain suspended in the air for long periods of time.
Radioactive aerosols are highly ionizing, have low concentrations, and are easily carried away by radioactive decay. They represent the main threat to human body irradiation.
Damage caused by strong electric arc light
Welding arc radiation mainly consists of visible, infrared and ultraviolet light. These types of radiation can affect the human body by being absorbed by human tissue, causing thermal, photochemical or ionization damage.
The brightness of visible light is about 10,000 times stronger than what is normally tolerated by the naked eye. When eyes are exposed to visible light radiation, it can cause pain, blurred vision and temporary loss of working capacity, commonly called “glare”.
The damage caused by infrared radiation to the human body comes mainly from its thermal effect on tissues. In welding processes, the eyes are exposed to strong infrared radiation, which can cause immediate burning and flash illusion. Long-term exposure can cause infrared cataracts, vision loss, and even blindness in severe cases.
Ultraviolet radiation (UV), also known as ultraviolet light, refers to electromagnetic waves with a wavelength of 100-400 nm. While a moderate amount of ultraviolet radiation can have positive effects on the human body, excessive exposure, such as in welding, can have adverse effects.
The harm caused by ultraviolet radiation to the human body comes mainly from its photochemical action, causing damage to the skin and eyes. Prolonged exposure of the skin to strong ultraviolet radiation can cause dermatitis, diffuse erythema, blisters, burning and itching. In severe cases, it can also cause systemic symptoms such as headaches, dizziness, fatigue, nervous excitement, fever and insomnia.
Excessive eye exposure to ultraviolet radiation can cause acute cornea and conjunctivitis, also known as electro-optic ophthalmia. Its symptoms include photophobia, excessive tearing, foreign body sensation, tingling, swelling of the eyelids, spasm, headache and blurred vision.
Dangers of welding fumes
During welding, a significant amount of metal welding dust is produced. This metallic powder has a small diameter, making it easier to inhale into the lungs. Due to its small size, it is difficult to remove from the body, causing injuries.
The intensity of the welding current is directly related to the concentration of dust, with greater intensity leading to greater concentration.
Without adequate dust removal measures, prolonged exposure to high concentrations of welding dust can result in occupational illnesses such as welder's pneumoconiosis, manganese poisoning, and metallic heat.
Reproductive toxicity
Over the last decade, several studies have been carried out both nationally and internationally on the reproductive toxicity of electrical welding. These studies mainly focus on the semen quality of male workers, the reproductive outcomes of female workers, and the mechanisms underlying harm.
The results indicate that female welding workers have a higher incidence of menstrual volume, shortening of the cycle, prolongation of the menstrual period, increased leucorrhoea, spontaneous abortion, premature birth and dysmenorrhea compared to the control group.
Male workers with manganese poisoning were found to have a uniform grayish-white appearance in their semen, with a normal PH value and a longer average liquefaction time compared to the control group. These workers were also found to have a lower mean ejaculate volume, total sperm count, sperm survival rate, motile sperm rate, and a significantly higher sperm deformity rate compared to the control group.
It is believed that manganese can negatively impact the spermatogenic system of male workers, having a direct toxic effect on sperm development, resulting in changes in the quality of male semen.
Studies carried out abroad have also reported that changes in the secretion of sex hormones and a decline in sperm quality do not affect the sex ratio of offspring.
Dangers of harmful gases
During welding, the high temperature and strong ultraviolet radiation of the welding arc can result in the formation of harmful gases around the arc. These gases include ozone, nitrogen oxides, carbon monoxide and hydrogen fluoride.
Ozone is a toxic, light blue gas that can be irritating. In high concentrations, it has a fishy odor and a slightly acidic flavor. The main damage of ozone to the human body is the strong irritation of the respiratory system and lungs, causing symptoms such as coughing, chest tightness, loss of appetite, fatigue, dizziness, systemic pain and, in severe cases, bronchitis and pulmonary edema.
Nitrogen oxides are also irritating toxic gases, with nitrogen dioxide being reddish-brown and having a distinct odor. The harm to the human body comes from its stimulating effect on lung tissue, causing the formation of nitric acid and nitrite after entering the respiratory tract. This strong stimulation and erosion of lung tissue can result in poisoning.
Symptoms of chronic poisoning include neurasthenia such as insomnia, headaches, loss of appetite and weight loss. High concentrations of nitrogen oxides can cause acute poisoning, with mild toxicity resulting in acute bronchitis and severe poisoning causing intense coughing, dyspnea, collapse, weakness, and other symptoms. The effects of nitrogen oxides on the human body are reversible and diminish over time.
In TIG welding, if adequate ventilation measures are not taken, the concentration of nitrogen oxides can exceed hygiene standards by more than ten to twenty times. The hygienic standard for nitrogen oxides in China is 5mg/m 3 . In the welding process, ozone and nitrogen oxides often coexist, making them more toxic. The toxicity of these two gases combined is generally 15-20 times that of a single gas.
Protective measures
(1) Ventilation measures
Adequate ventilation system must be provided at the argon arc welding location to eliminate harmful gases and smoke.
In addition to general area ventilation, multiple axial flow fans can be installed in high workload welding areas where welding machines are concentrated for external exhaust.
Local ventilation measures can also be taken to remove harmful gases near the arc, such as an open arc smoke exhaust hood, a smoke exhaust welding gun, a small portable fan, etc.
(2) Radiation protection measures
When possible, it is recommended to use cerium and tungsten electrodes with a very low radiation dose.
When grinding thorium tungsten electrodes and cerium tungsten electrodes, a sealed or suction grinding wheel must be used.
Operators must wear personal protective equipment, such as masks and gloves, and wash their hands and face after handling the electrodes.
Both thorium tungsten electrodes and cerium tungsten electrodes must be stored in an aluminum container.
(3) Measures for high frequency protection
To reduce and mitigate the effects of high frequency electromagnetic fields, the following measures must be taken:
- The workpiece must be properly grounded and the welding gun handle and ground wire must be shielded with braided metal wire.
- The frequency must be adjusted accordingly.
- Avoid using high frequency oscillators as an arc stabilizing device to minimize high frequency electrical action time.
(4) Other personal protective measures
During argon arc welding, due to the strong effects of ozone and ultraviolet light, it is recommended to wear work clothes made from materials other than cotton, such as acid-resistant tweed or tussah silk.
In situations where welding takes place in a confined space and local ventilation cannot be used, personal protective measures such as a supply air helmet, supply air mask or gas mask must be used.
