Dangers of welding and cutting operations

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Welding and cutting operations pose significant risks and hazards, and their working conditions and environments are particularly special. (1) Hazardous factors in welding operations: ① High-temperature work – During welding and gas cutting, the welding arc and the flame from gas cutters are both high-temperature heat sources; the temperature at the center of the manual arc can exceed 4200 K ； The arc temperature in carbon dioxide gas shielded welding can reach 6000–10000 K. ②Exposure to flammable and explosive gases, such as acetylene gas used in gas welding and cutting, as well as the presence of flammable, explosive, and harmful substances in the work area. Therefore, welding and cutting operations often involve exposure to flammable, explosive, toxic, and harmful gases, posing a risk of fire and explosion. ③Coming into contact with live parts: During arc welding, tasks such as changing electrodes, moving or adjusting welding equipment, welding torches, cables, etc., often require workers to come into contact with live parts. Some operations require a higher operating voltage; for example, the no-load voltage in plasma arc cutting is high, ranging from 150 to 400 V. ④Equipment under pressure, such as various types of gas cylinders and pressure pipelines, are themselves considered pressure vessels. During welding and cutting operations, it is sometimes necessary to weld pressure-bearing equipment as well. ⑤Working in special environments: Welding and cutting tasks are often carried out in special environments, such as welding and cutting at heights or in confined spaces. ⑥Generation of toxic and harmful fumes: Under the high temperatures associated with welding and cutting, certain fumes that are harmful to human health are produced. For example, at arc welding sites, dusts such as manganese oxide, ozone, and nitrogen oxides are generated. ⑦Arc light radiation is generated; the visible light intensity in arc welding is about ten thousand times greater than the intensity that the human eye can tolerate. Infrared heat radiation and ultraviolet rays can strongly irritate and damage the eyes and skin. In particular, stronger ultraviolet rays are generated during TIG welding and plasma arc cutting processes. ⑧Noise generation. (2) Welding and cutting operations are prone to accidents and occupational hazards. From the perspective of hazardous factors, such operations can lead to injuries, fatalities, as well as occupational poisoning and diseases. These can be classified into the following categories: ① Fires and explosions. As mentioned earlier, during welding and cutting processes, operators often come into contact with flammable and explosive substances such as acetylene, organic materials, and compressed pure oxygen ； Contact with pressure vessels, fuel containers, and pipelines is required ； During welding and cutting processes, such as the flame in gas welding or the arc in electric welding, these are forms of open-flame operations. Sparks are generated during welding and cutting, which can create conditions conducive to fires and explosions; even the slightest carelessness can lead to such accidents. ②Electric shock: When performing manual arc welding, there are many opportunities for coming into contact with electricity, such as when replacing welding electrodes or adjusting the welding current. If insulation protection is inadequate or safety procedures are not followed, electric shock accidents can occur, especially in humid conditions, during the rainy season or summer, as well as when welding in confined spaces. ③Burns: During welding and cutting processes, the high temperature of the welding flame or arc causes slag to splash and sparks to fly, which can easily lead to burns. This is a common type of accident that often occurs among workers involved in welding and cutting tasks. ④Falls from height: Welding and cutting operations carried out during installation and maintenance can easily lead to falls from height. ⑤Object impact: During welding and cutting processes, it is often necessary to move and turn heavy welding and cutting components ； Under metal structures or machinery, operations such as overhead welding are often required, which frequently leads to mechanical injuries such as collisions, presses, and crushes. When carrying out cross-work at heights on tall buildings or equipment, falls from height and object strike accidents are likely to occur. ⑥Acute poisoning: Accidents of acute poisoning can easily occur when repairing or welding containers, pipes, or systems that contain toxic substances. During welding, some toxic and harmful gases are generated, especially when working in poorly ventilated semi-enclosed containers or confined spaces. Due to the high concentrations of such toxic and harmful gases as well as toxic metal vapors, acute poisoning can occur. ⑦Welding dust can cause chronic poisoning, welder’s pneumoconiosis, and metal fume fever. During welding, under the high temperature of the arc, the electrode (including its coating and core) and the metal being welded undergo intense vaporization, resulting in the release of various metal fumes as well as harmful substances such as carbon monoxide. These metal fumes are oxidized, cooled, and condensed in the air to form dust. Inhaling dust to a certain extent can cause chronic poisoning, welder’s pneumoconiosis, and metal fume fever. For welders and cutters, working with high-manganese steel over a long period of time may lead to manganese poisoning ； Welding or cutting lead-containing metals or workpieces with lead-based paint on their surfaces can cause lead poisoning ； Metal fume fever can be triggered by inhaling large amounts of fresh, fine metal vapor or metal oxide smoke. ⑧Damage to the human body caused by arc light radiation: The visible light emitted by arc light radiation is 10,000 times stronger than the level that the human eye can safely tolerate. Such intense light can cause glare and discomfort, and even lead to changes in vision. The infrared thermal radiation emitted by arc light can cause the lens of the eye to become cloudy, and in severe cases this can lead to \"cataracts\". The ultraviolet rays emitted by arc light radiation can strongly irritate and damage the eyes and skin, causing photokeratitis and photodermatitis. Processes such as inert gas shielded welding and plasma cutting generate particularly high levels of radiation, which can often cause damage to the skin and eyes in a short period of time. ⑨Heat stroke: In welding environments, there is a large amount of heat generated by rod baking, preheating of the workpieces, and the welding arc during the welding process. Especially in hot seasons, workers sweat heavily, which can easily lead to heat stroke. ⑩Other hazards: The high-frequency electromagnetic fields generated during high-frequency arc initiation in gas tungsten arc welding and plasma arc cutting (for example, the intensity of such high-frequency electromagnetic fields in gas tungsten arc welding when an high-frequency oscillator is used for arc initiation can reach 140–190 V/m) are harmful to human health. There is a certain level of noise during welding and cutting processes, and this noise varies depending on the method used. Thorium, which is used in thoriated tungsten electrodes for tungsten inert gas welding and plasma arc cutting, is a naturally radioactive substance. During the grinding of these electrodes and welding operations, thorium dust as well as thorium in aerosol or gaseous form can enter the bodies of workers, causing internal radiation exposure that poses serious risks to human health.