Arc welding Machine is also known as the Transformer, is a special transformer, it is the network voltage alternating current into a suitable for arc welding low-voltage alternating current, by the main transformer and the necessary adjustment parts and indicators and other components. Arc welding machine mainly has movable iron core type, the same posture and the movable circle type three kinds. It has the advantages of simple structure, Ise Yishu, low cost and high efficiency. But its current waveform is sine wave, the output is the AC descent characteristic, the arc stability is poor, the power factor is low, but the magnetic partial blow phenomenon rarely produces, the no-load loss is small, generally applies in the hand arc welding, the submerged arc welding and the Tungsten pole Argon arc welding and so on methods.
One, easy to cause electric shock accident
1, welding process, because the welder to often change the electrode and adjust the welding current, operation should be directly contact with electrodes and plates, and welding power supply is usually 220v/380v, when the Electrical Safety protection device failure, labor protection supplies unqualified, operator illegal operation, it may cause electric shock accident. If welding in metal containers, pipelines or damp places, the risk of electrocution is greater.
2, Welding machine no-load, two winding voltage is generally in 60~90v, because the voltage is not high, easy to be neglected by welders, but its voltage exceeds the specified safety voltage 36V, still have a certain risk. Assuming that the welder no-load voltage of 70V, people in high-temperature, humid environment, at this time the human body resistance R about 1600 Ω, if the welder hand contact jaws, through the human body current I as: I=v/r=70/1600=44ma, in the current role, welder's hands will be spasm, easy to cause electric shock accident.
3, because most of the welding operations in the open air, welding machine, welding line and power line in the high-temperature, humid (construction site) and dust environment, and the stove often overloaded operation, easy to make the power line, electrical wiring insulation aging, insulation performance is reduced, easy to lead to leakage accident.
II. Easy to cause fire and explosion accidents
Because the welding process will produce arc or open flame, in the place of flammable goods operation, very easy to trigger fire. Especially in the inflammable and explosive device area (including pits, trenches, grooves, etc.), the storage of flammable and explosive media containers, towers, cans and pipelines on the risk of a greater degree of welding.
III. Easy to burn
Because the welding process will produce arc, metal slag, if welder welding did not wear a good welding special protective overalls, gloves and shoes, especially in the high place for welding, because of the spark spatter welding, if not to take protective measures, easily caused by welders themselves or under the work surface of the construction staff skin burns.
IV. Easy to cause electro-optic eye inflammation
Because of the intense fire in the visible light and a large number of invisible ultraviolet rays, people's eyes have a strong role in stimulating injury, long time direct exposure will cause eye pain, photophobia, tears, fear of the wind, easily lead to eye conjunctival and corneal inflammation (commonly known as electro-optic eye inflammation).
V. With the effect of light radiation
The arc light produced in welding contains infra-red, ultraviolet and visible light and has a radiation effect on the human body. Infrared radiation has the effect of heat, in the high-temperature environment when welding easily lead to heat stroke workers; ultraviolet radiation has photochemical action on the skin of people have harm, while prolonged exposure to exposed skin will also make skin peeling, visible light long time exposure will cause eye drops.
VI. Easy to produce harmful gases and soot
As the arc temperature in the welding process reaches over 4,200 ℃, the phenomenon of gasification, evaporation and condensation after melting of the electrode core, the medicine skin and the metal weldment will produce a large amount of manganese-chromium oxide and harmful soot, meanwhile, the high temperature of the arc light and the strong radiation effect will make the ambient air produce ozone, nitrogen oxides and other poisonous gases. For a long time in the case of poor ventilation conditions engaged in welding operations, these poisonous gases and soot by the human body inhalation, the human body Health has a certain impact.
VII. Easy to cause a fall in the sky
Because of the construction needs, welders should often ascend welding operations, if the prevention of high-altitude fall measures did not do, scaffold erection is not standardized, not after acceptance of the use of the cross work to take measures to prevent the prevention of objects; Welder personal safety protection awareness is not strong, climb the operation without wearing a helmet, not wear safety belts, once encountered walking careless, Accidental objects such as the impact of such reasons, it is possible to cause the occurrence of high crashes.
Eight, easy to cause poisoning, suffocation
Welders often enter metal containers, equipment, pipe, tower, storage tank, such as closed or semi-closed place welding, if the storage and transportation or production of toxic and harmful medium and inert gas, and so on, once the poor management, protection measures are not in place, very easy to cause workers poisoning or hypoxia asphyxia, this phenomenon occurs in oil refining, chemical and other enterprises.
IX. Measures to prevent electric shock
The general principle is to take insulation, shielding, isolation, leakage protection and personal protection and other safety measures to avoid touching the body charged body. The specific methods are:
1, improve the welding equipment and circuit insulation performance. The use of welding equipment and power cables must be qualified products, its electrical insulation performance and the use of voltage levels, the surrounding environment and operating conditions to adapt to; welding machine should be arranged for the day-to-day maintenance and maintenance, to prevent the sun and rain, lest the electrical insulation performance of welder reduced.
2, when the welder failure to overhaul, move the work place, change the joint or replace the safety device, the operation must first cut off the power supply.
3. Do not forget to install the leakage protector at the same time when the welding machine is installed to ensure that the person will automatically lose power once the electric shock. In wet or metal containers, equipment, components welded, must choose the rated action current is not less than 15mA, rated action time less than 0.1 seconds of leakage protector.
4. The end head of the welding machine housing and two windings should take good protective earthing or 0 measures. When the power supply is three-phase wire or single-phase system should be installed to protect the grounding line, the resistance value of not more than 4 Ω; when the power supply for the three-phase four-wire neutral grounding system, the protection should be installed 0 lines.
5, to strengthen the operation of personnel safety knowledge and self-protection awareness education, require welders work must wear insulating shoes, wear special insulating gloves. It is forbidden to apply the welding in the open air on rainy days and the person must stand on a dry plank or rubber insulator in a particularly humid place.
6. The use of metal structures, pipelines, rails and other metal connections for wire use is prohibited. In a metal container or in a particularly humid place, the power supply of the line lamp must use the following safety voltage of 12V.
X. Fire and explosion prevention measures
1, in the inflammable and explosive site welding, welding must be in accordance with the provisions prior to the use of fire permits, after approval by the relevant departments can work, strict "three not hot."
2, before the official welding inspection work and the surrounding area whether there are flammable explosive materials, operating surface, such as paint-like anti-corrosion substances, if there should be good treatment in advance. In the vicinity of the operation of the production device area, oil tank in the welding operations, must be masonry firewall, if there is high-altitude welding operations, should also use asbestos plate or iron plate to be isolated to prevent the Martian splash.
3, such as in the production, storage and transportation of flammable and explosive media containers, the equipment or pipeline welding, before welding must check with its connected equipment, the pipeline is closed or the blind plate plugging off, and according to the provisions of the purge, cleaning, replacement, sampling test, after the analysis of qualified welding can be applied.
The measures of preventing burns
1, welder welding must be properly empty wear the welder's special protective overalls, insulating gloves and shoes. When using large current welding, the electrode should be fitted with a protective cover.
2, the newly welded parts should be promptly covered with asbestos plate, to prevent the foot, the body directly touched the cause of scald.
3, the welding electrode should be replaced at high altitude should be centralized stacking, do not throw, so as not to scald the workers below.
4, in the cleaning of welding slag should wear protective mirror, high altitude in the butt welding or transverse welding, due to the serious splash of Mars, should take quarantine measures.
12, prevention of electro-optic eye inflammation measures
According to the size of the welding current, should be timely selection of appropriate mask goggles filter, with the welders work with other personnel in the welding should wear colored eye protection.
13. Radiation prevention measures
Welders and surrounding workers should wear good labor supplies when welding. It is forbidden to observe the arc light without the electric welding mask, without tinted spectacles, to reduce the exposure of skin, to wear shorts and short coat in the summer, and to apply the ultraviolet protective cream to the exposed skin.
14. Measures against harmful gases and soot
1, the rational design of welding technology, as far as possible using single-sided welding double-sided molding technology, reduce the metal container welding work volume.
2, such as in the small space or airtight container welding operations, must take mandatory ventilation measures to reduce the operating space of harmful gases and soot concentrations.
3, as far as possible using automatic welding, semi-automatic welding instead of manual welding, reduce welding personnel exposure to harmful gases and soot opportunities.
4, the use of low dust, low toxicity electrode, reduce the operating space of harmful soot content.
5, welding, welders and other personnel around should wear dust masks, reduce smoke inhalation body.
XV. Measures against high fall
Welders must do regular physical examination, where there are hypertension, heart disease, epilepsy and other medical history personnel, prohibit ascending welding. The welder must fasten the safety belt and wear safety helmet correctly when he ascends the work. Before welding, should check the height and surroundings to see if the foothold is stable and secure, and whether the scaffold and other safety protection facilities meet the safety requirements, when necessary, should be under the operation and the surrounding safety nets. Protective measures should be taken to cover the upper and lower cross operations.
16, prevention of poisoning, suffocation measures
1, where the transportation or production of toxic and harmful media, inert gas containers, equipment, pipelines, towers, cans, such as closed or semi-closed place welding, before the operation must cut off all the process equipment connected with, at the same time to its cleaning, purging, replacement, and in accordance with the provisions of the equipment operation permit, after sampling analysis, The qualified rear can enter the work.
2, under normal circumstances should be done every 4 small into the analysis, if the conditions change should be at any time sampling analysis; At the same time, the site should be equipped with a proper amount of air (oxygen) gas respirator, in case of emergency use.
3, the operation of the application of personal safety monitoring, welders should be timed rotation operations. For the airtight strong and easy to hypoxia operating equipment, the use of forced ventilation to make up oxygen (prohibit direct oxygen), to prevent hypoxia asphyxia. Long time operation, must pay attention to rest.