gdzhxc.com 2021-11-01 199
Argon arc welding is mainly used for welding of aluminum and aluminum alloys, stainless steel, copper and copper alloys, magnesium and magnesium alloys, titanium and titanium alloys, high-temperature alloys, etc. It is widely used in many important industrial sectors. In addition to the same electric shocks, burns, and fires as electrode arc welding, argon arc welding also has high-frequency electromagnetic fields, electrode radioactivity, and arc damage that is much stronger than arc welding. Welding fumes and toxic gases are harmful.
Understanding the causes and consequences of these injuries can enable welders to be better prevented and their health guaranteed.
Argon arc welding is an arc welding method that uses an inert gas-argon as a shielding gas. The argon sprayed from the welding gun nozzle during welding creates a thick and dense gas shielding layer in the welding area, so that it is in contact with the empty space. Insulation, under the protection of argon laminar flow, the heat generated by the arc burning between the electrode (tungsten electrode or welding wire) and the work is used to melt the welded area, and fill or not fill the welding wire to connect the separated metal into one. So as to obtain a strong welded joint.
The harmful factors of argon arc welding that affect the human body are as follows:
1. High frequency electromagnetic field
Welding usually uses a high-frequency oscillator with a frequency of 200-500kHz, a voltage of 2500-3500V, and an electric field strength of 140-190V/m. When the arc is ignited, the intensity of the high-frequency electromagnetic field generated is between 60 and 110VAn, which is several times higher than the reference sanitary standard. Long-term exposure of welders to high-frequency electromagnetic fields can cause autonomic dysfunction and neurasthenia. However, due to the short time, it has little effect on the human body. If the arc is frequently started, or the high-frequency oscillator is used as a stabilizing arc device in the welding process, the high-frequency electromagnetic field can become one of the harmful factors.
The thorium tungsten used in argon arc welding contains 1% to 1.2% thorium oxide. Thorium is a radioactive element and may be affected by radiation during the welding process and the contact process with thorium tungsten rods. Argon arc welding welders consume 100-200g of thorium oxide during a normal working day (5 hours in actual work), and the welder’s continuous working time is only 30-60min each time. The radioactive dust produced is very small and has little effect 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; the second is when the thorium tungsten rod is ground and the place where the thorium tungsten rod is stored, the concentration of radioactive aerosol and radioactive dust can be Meet or exceed hygiene standards. Radioactive substances invade the body, which can cause chronic radiation diseases, which are mainly manifested in the general weakening of the state of function. You can see obvious weakness, significantly reduced resistance to infectious diseases, and weight loss.
3. Ultraviolet argon arc welding
In argon arc welding, the arc temperature is high, so the ultraviolet intensity of argon arc welding is 5-10 times higher than that of ordinary arc welding. The ultraviolet intensity generated by argon arc welding is high and the wavelength is short, which can cause damage to the eyes and skin of the operator. When the argon arc welding arc light enters the eyes, firstly feel irritation and fatigue. After about 4-6 hours, the vision is unclear. In severe cases, the eyes have tingling and tearing. Recover health in a short time.
Argon arc welding welders feel dry eyes, erythema on the exposed parts of the skin (neck, wrist, chest, etc.), and even peeling. These are all related to the strong ultraviolet light of argon arc welding. In addition, strong ultraviolet light and argon arc Strong visible light during welding also has a strong destructive effect on cotton fabrics. When argon arc welding, in order to reduce the damage of ultraviolet rays, argon arc welding welders should wear white canvas overalls and gloves. The face and neck must be covered with a long face mask. Be careful not to roll up sleeves or wear short-sleeved shirts during operation. Open the collar.
4. Harmful gases
The amount of ozone produced during argon arc welding is related to the type of shielding gas used in welding, welding materials and the size of the argon arc welding current. In gas-shielded welding, when welding the same material, arc welding with argon gas protection produces more ozone than other gas-shielded welding. In the case of poor ventilation, when the ozone concentration exceeds a certain range, welding T Respiratory symptoms such as dry throat, dry tongue, cough, and chest tightness appear.
Another harmful gas produced by argon arc welding is nitrogen oxides. Due to the high-temperature arc effect of argon arc welding, nitrogen in the air can generate nitrogen oxides, which are difficult to dissolve in water, but can directly inhale the deep part of the human body's respiratory tract and cause pneumonia. Under normal circumstances, the concentration of nitrogen oxides is lower than the maximum allowable value of 5mg/m3. Therefore, compared with the amount of ozone, a single oxide has a smaller effect on argon arc welding welders.
The experimental results of the effects of ozone and nitrogen oxides on rabbits show that: in the early stage of the experiment, the rabbits in the experimental group showed obvious non-eating, reduced activity, fatigue and other phenomena; in the middle of the experiment, the above symptoms weakened, which It may be related to the adaptability of rabbits to ozone and nitrogen oxides.
5. Metal fume generated by argon arc welding
Metal fume refers to a kind of fume produced by argon arc welding, and its type is related to the material to be welded, welding wire and other materials. Since the smoke and dust contain solid particles, when welding heavy metals or radioactive substances with strong toxicity, great attention should be paid. The large amount of metal dust produced during the welding process is easier to be absorbed into the lungs of the human body and cause disease. The higher the welding current intensity, the higher the dust concentration. In the case of high welding dust concentration and no corresponding dust removal measures, long-term exposure to welding dust can cause occupational diseases such as welder's pneumoconiosis, manganese poisoning and metal fever.
Safety protection measures:
1. Protection of welding fumes and toxic gases
Ventilation measures: There should be good ventilation devices at the argon arc welding work site to exhaust harmful gases and smoke. In addition to the ventilation of the workshop, several fans can be installed to exhaust air in places where the welding workload is heavy and the welding machines are concentrated. In addition, local ventilation measures can also be used to remove harmful gases around the arc, such as using open arc fume hoods, fume extraction welding torches, and portable small fans.
2. Radiation wins protection
(1) The sharpened thorium tungsten rod should be equipped with a special grinding wheel, and the grinding wheel should be equipped with dust removal equipment. The abrasive debris on the ground of the grinder is often wet-swept away, and concentrated and deeply buried. Tiles or terrazzo should be laid on the ground and walls to facilitate cleaning of dirt.
(2) A single room should be set up in the welding place. The storage location of thorium tungsten rods should be fixed in the basement and stored in a closed box. Large amounts of storage should be placed in iron boxes, and ventilation devices should be installed.
(3) During the manual welding operation, a ventilation helmet must be worn, or other effective ventilation measures must be taken. Wear a dust mask when sharpening the thorium tungsten electrode.
(4) Use a stable arc fume exhaust hood as much as possible according to the production conditions, and the hood should not be opened casually during operation.
(5) The process specifications should be selected reasonably to avoid excessive burning of the thorium tungsten electrode.
(6) Wash your hands with running water and soapy water after touching the thorium tungsten electrode.
3. Measures to protect high frequency
(1) The workpiece is well grounded, and the welding torch cable and ground wire should be shielded with metal braided wire.
(2) Reduce the frequency appropriately.
(3) Try not to use a high-frequency oscillator as an arc stabilizing device to reduce the time of high-frequency electrical action.
4. Other personal protective measures
During argon arc welding, due to the strong effects of ozone and ultraviolet rays, it is advisable to wear non-cotton work clothes (such as acid-resistant cloth, tussah silk, etc.). In the case of welding in the container and local ventilation cannot be used, personal protective measures such as air-supply helmets, air-supply masks or gas masks can be adopted.
There are many harmful factors in the argon arc welding operation, and there should be a clearer understanding of this. Try to choose a place with air circulation for welding. When welding, try to choose electrode materials with low radioactivity of thorium-tungsten and cerium-tungsten. If possible, regular physical examinations should be carried out. At work, we must combine work and rest, usually pay attention to exercise, and take part in more sports activities. If the welder pays attention to the corresponding protection at work, the damage caused by this can be avoided or reduced.