In addition to the same electric shock, burn and fire as manual ARC welding, there are also high-frequency electromagnetic fields, electrode radiation, arc damage, welding smoke and toxic gas, which are much stronger than manual arc welding.The main ones are high-frequency electricity and ozone.
In GTAW and plasma arc welding, high frequency oscillator is commonly used to excite arc initiation, and some AC argon arc welders also use high frequency oscillator to stabilize arc.The high-frequency oscillators commonly used for welding have a frequency of 200-500 kilocytes, a voltage of 2500-3500 volts, a high-frequency current intensity of 3-7 mA, and an electric field intensity of about 140-190 volts/meter.
Long-term exposure of welders to high-frequency electromagnetic fields can cause neuronal dysfunction and neurasthenia.Symptoms include general malaise, dizziness, excessive dreaming, headache, loss of memory, fatigue, loss of appetite, insomnia, and low blood pressure.
If only the use of high frequency oscillator arc, because of the short time, the impact is small, but long-term contact is also harmful, must use effective protective measures.
Thorium tungsten electrode used in tiG and PLASMA arc welding contains 1-1.2% thorium oxide. Thorium is a radioactive substance and is affected by radiation during welding and contact with thorium tungsten rod.Radiation ACTS on the body in two forms: in vitro irradiation, and in vivo irradiation through the respiratory and digestive systems.
A large number of investigations and measurements of shielded argon arc welding and plasma arc welding have proved that their radioactive harm is relatively small, because thorium tungsten electrodes consume only 100-200 mg of thorium tungsten per day, and the radiation dose is very small, which has little effect on human body.
Welding arc radiation mainly includes visible light, infrared ray and ultraviolet ray.They act on the human body and are absorbed by human tissues, causing damage to human tissues by thermal, photochemical or ionizing action of tissues.
Under the action of high temperature and strong ultraviolet ray in welding arc, a variety of harmful gases are formed around arc zone, among which ozone, nitrogen oxide, carbon monoxide and hydrogen fluoride are the main gases.
Oxygen in the air reacts with short-wave ultraviolet radiation to form ozone (O3).Ozone is a light blue gas with a pungent smell.When the concentration is high, the smell is fishy.When the concentration is higher, it has a slightly sour smell in the stench.
Its harm to human body basically is to have strong stimulative effect to respiratory tract and lung.When ozone concentration exceeds a certain limit, it often causes cough, dry throat, dry tongue, chest tightness, loss of appetite, fatigue, dizziness, nausea and systemic pain.Serious, especially in the airtight container welding and poor ventilation, but also can cause bronchitis.