The harm degree of argon arc welding is relatively greater than that of electrode arc welding, but it is not so great as to be feared.
The infrared radiation is about 1 ~ 1.5 times that of ordinary electrode arc welding, and the ultraviolet radiation generated by argon arc welding is about 5 ~ 20 times that of electrode arc welding.
When welding in a limited space, the concentration of ozone can increase to a dangerous level. During the welding process, harmful gases such as carbon dioxide, carbon monoxide and metal dust will be produced, which will do some harm to welders.
Therefore, in the welding process, we should do a good job in protection, select electrode materials, and try to select cerium tungsten with low radioactivity.
Wear masks and gloves when grinding electrodes, and wash hands after work to minimize hazards.
Harm of high-frequency electromagnetic field
The high-frequency oscillator is usually used for welding, with a frequency of 200 ~ 500KHz, a voltage of 2500 ~ 3500v and an electric field strength of 140 ~ 190V / m.
During arc striking, the high-frequency electromagnetic field intensity generated is between 60 ~ 110V / m, several times higher than the reference hygienic standard (20V / M).
In non-melting electrode argon arc welding and plasma arc welding and cutting, the high-frequency oscillator is often used to excite the arc, and some AC argon arc welding machines also use a high-frequency oscillator to stabilize the arc.
Under the action of high-frequency electromagnetic field, the human body can absorb certain radiation energy and produce biological effects, mainly thermal effect.
The intensity of high-frequency electromagnetic field is affected by many factors, such as distance, the closer the oscillator and oscillation circuit, the higher the field strength, and vice versa.
In addition, it is related to the shielding degree of the high-frequency part.
The human body will produce biological effects under the action of the high-frequency electromagnetic field.
Welder’s long-term exposure to a high-frequency electromagnetic field can cause autonomic nerve dysfunction and neurasthenia.
Symptoms include general discomfort, dizziness, headache, fatigue, loss of appetite, insomnia and low blood pressure.
If only the high-frequency oscillator is used for arc striking, the impact is small due to the short time.
If the high-frequency oscillator is used frequently or continuously as an arc stabilizing device in the welding process, the high-frequency electromagnetic field can become one of the harmful factors.
Thorium tungsten used in argon arc welding contains 1% – 1.2% thorium oxide.
Thorium is a radioactive element that can emit α，β，γ three kinds of rays.
It may be affected by radiation during welding and contact with thorium tungsten rod.
Through a large number of investigations, the daily consumption of thorium tungsten rod is only 100-200mg, and the radiation dose is very small, which has little impact on the human body.
However, when welding in the container, the ventilation is not smooth, and the radioactive particles in the smoke may exceed the hygienic standard;
Second, when grinding thorium tungsten rods and where thorium tungsten rods are stored, the concentration of radioactive aerosol and radioactive dust can reach or even exceed the hygienic standard.
When radioactive substances invade the body, they can cause chronic radioactive diseases and form internal irradiation, which is mainly manifested in the weakening of the general functional state, obvious weakness, obvious reduction of resistance to infectious diseases, weight loss and other symptoms.
Radioactive aerosol, solid or liquid particles containing radionuclides suspended in air or other gases.
A dispersion system in which solid or liquid radioactive particles are suspended in an air or gas medium.
The basic characteristic of aerosol is instability. Particles less than 0.1 micron make Brownian motion in the gas and do not settle due to gravity;
Particles of 1 ~ 10 microns settle slowly and are suspended in the air for a long time.
Radioactive aerosols have high ionization effect, low concentration and are easy to be charged on particles (produced by radioactive decay).
Radioactive aerosols are the main threat to human body irradiation.
Harm of strong electric arc light
Welding arc radiation mainly includes visible light, infrared and ultraviolet.
They act on the human body and are absorbed by the human tissue, causing thermal, photochemical or ionization of the tissue, causing damage to the human tissue.
The luminosity of visible light is about 10000 times greater than that normally borne by the naked eye.
When visible light radiates people’s eyes, it will produce pain and can’t see clearly. It is usually called “dazzling” and lose the ability to work in a short time.
The harm of infrared rays to the human body is mainly caused by the thermal effect of tissue.
In the welding process, the eyes are exposed to strong infrared radiation, which will immediately feel strong burns and burning pain, resulting in flash illusion.
Long term exposure may cause infrared cataracts, vision loss, and blindness in severe cases.
Ultraviolet radiation (UV), also known as ultraviolet, refers to electromagnetic waves with a wavelength of 100-400 nm.
An appropriate amount of ultraviolet radiation can have beneficial effects on the human body, but excessive radiation will have adverse effects on the human body (such as welding ultraviolet radiation).
The harm of ultraviolet rays to the human body is mainly photochemical action, causing damage to human skin and eyes.
After the skin is exposed to strong ultraviolet radiation, it can cause dermatitis, diffuse erythema, sometimes small blisters and exudates, burning and itching;
When the effect is strong, it is accompanied by systemic symptoms: headache, dizziness, fatigue, nerve excitement, fever, insomnia, etc.
Excessive ultraviolet irradiation of human eyes can cause acute corneal and conjunctivitis, namely electro-optic ophthalmia.
Its symptoms are high photophobia, tears, foreign body sensation, tingling, eyelid swelling, spasm, headache and blurred vision.
Hazards of welding fume
A large amount of metal welding dust will be generated during welding.
The metal powder produced by welding has a small diameter, which is easy to suck into the lungs. Because the diameter is very small, it is difficult to discharge out of the body, so lesions occur.
The higher the welding current intensity, the higher the dust concentration.
When the welding dust concentration is high and there are no corresponding dust removal measures, long-term exposure to welding dust can cause occupational diseases such as welder pneumoconiosis, manganese poisoning and metal heat.
In recent 10 years, some studies on the reproductive toxicity of electric welding have been carried out at home and abroad, mainly involving the semen quality of male workers, the reproductive outcome of female workers and the damage mechanism.
The results showed that the menstrual volume, cycle shortening, menstrual period prolonging, leucorrhea increasing, spontaneous abortion, premature delivery and dysmenorrhea of female welding workers were higher than those of the control group.
The appearance of semen of male workers with manganese poisoning was uniform gray white, the PH value was normal, and the average liquefaction time was longer than that of the control group.
The results showed that the average ejaculation volume, total sperm count, sperm survival rate and motile sperm rate of male workers with manganese poisoning were lower than those of the control group, and the sperm deformity rate of male workers with manganese poisoning was significantly higher than that of the control group.
It is considered that manganese can affect the spermatogenic system of male workers, have a direct toxic effect on sperm development, and kill sperm, resulting in the change of male semen quality.
It has also been reported abroad that the changes of sex hormone secretion and the decline of sperm quality have no effect on the sex ratio of offspring.
Hazards of harmful gases
Under the action of high temperature and strong ultraviolet radiation of welding arc, a variety of harmful gases are formed around the arc, mainly including ozone, nitrogen oxide, carbon monoxide and hydrogen fluoride.
Ozone is an irritating toxic gas, light blue. When the concentration is high, it gives off a fishy smell; High concentration ozone also has a slightly sour taste.
The main harm of ozone to the human body is strong irritation to the respiratory tract and lungs.
It often causes cough, chest tightness, loss of appetite, fatigue and weakness, dizziness, systemic pain, etc. in severe cases, it will also cause bronchitis and pulmonary edema.
Nitrogen oxides are irritant toxic gases. Nitrogen dioxide is reddish-brown and has a special odor. The harm of nitrogen oxides to the human body is mainly the stimulating effect on lung tissue.
After being sucked into the respiratory tract, it gradually reacts with water in the alveoli to form nitric acid and nitrite, which strongly stimulates and corrodes the lung tissue and causes poisoning.
The main symptoms of chronic poisoning are neurasthenias, such as insomnia, headache, loss of appetite and weight loss.
High concentration of nitrogen oxides can cause acute poisoning, of which mild toxicity only occurs acute bronchitis;
Severe poisoning will cause severe cough, dyspnea, collapse, weakness and other symptoms.
The effect of nitrogen oxides on the human body is also reversible.
With the increase of separation time, its adverse effects are gradually reduced or eliminated.
In TIG welding, if ventilation measures are not taken, the concentration often exceeds more than ten times or even dozens of times of the hygienic standard.
The hygienic standard of nitrogen oxide (converted into nitrogen dioxide) stipulated in China is 5mg / m3.
In the welding process, ozone and nitrogen oxides usually exist at the same time, so they are more toxic.
Generally, two toxic gases exist at the same time, which is 15-20 times higher than that of a single toxic gas.
(1) Ventilation measures
A good ventilation device shall be provided at the argon arc welding site to discharge harmful gas and smoke.
In addition to the ventilation of the plant, several axial flow fans can be installed at the place where the welding workload is large and the welding machines are concentrated for external exhaust.
In addition, local ventilation measures can also be adopted to remove harmful gases around the arc, such as open arc smoke exhaust hood, smoke exhaust welding gun, portable small fan, etc.
(2) Radiation protection measures
Cerium tungsten electrodes with extremely low radiation dose shall be used as far as possible. During the processing of thorium tungsten electrode and cerium tungsten electrode, sealed or suction grinding wheel shall be used for grinding.
The operator shall wear personal protective articles such as masks and gloves, and wash his hands and face after processing.
Thorium tungsten electrode and cerium tungsten electrode shall be stored in an aluminum box.
(3) Measures for high-frequency protection
In order to prevent and weaken the impact of high-frequency electromagnetic field, the following measures are taken:
1) The workpiece shall be well grounded, and the welding gun cable and ground wire shall be shielded with metal braided wire;
2) Reduce the frequency appropriately;
3) Try not to use high-frequency oscillator as arc stabilizing device to reduce high-frequency electric action time.
(4) Other personal protective measures
During argon arc welding, due to the strong effect of ozone and ultraviolet light, it is advisable to wear non cotton work clothes (such as acid-resistant tweed, tussah silk, etc.).
In case of welding in the container and local ventilation cannot be adopted, personal protective measures such as air supply helmet, air supply mask or gas mask can be adopted.