Hazardous factors and protection in the hottest we

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Hazard factors and protection in welding operation

in welding manufacturing, when welding engineers choose appropriate welding methods for a processing object to meet the arrival of a new era in the field of materials, they will first consider how to achieve the required quality of weldments with the lowest production cost. Accordingly, they will also consider improving the welding speed and cladding rate to obtain higher productivity. In addition, qualified welding equipment Welders are also selected. However, in the above many choices, as a sensible welding engineer, we must pay attention to the possible impact of his choice on the welding operation and the surrounding environment, that is, in order to ensure the safety of welding operation, we must make a prediction and risk assessment of the possible hazard factors. The common hazard factors in the fusion welding process are listed in Table 1

1 hazards of fusion welding process to welders

1.1 electric shock

in all manual arc welding operations,% of welders are close to the parts being welded. Although the voltage range of the welding arc is 10~40v, the no-load voltage of the welding power supply can usually be as high as 80V to meet the voltage demand during arc starting. This voltage (80V) is not high compared with 220V of mains power. According to the standards of the International Electrotechnical Commission, in a dry environment, the voltage of AC 500V and DC 220V will not be dangerous to a healthy person. However, if it is in a humid place or a narrow metal object space, 80V voltage is enough to cause a fatal electric shock. Especially when replacing welding rods, welders rely on insulation Schulman of gloves, and calendered parts are mainly aluminum plates for car bodies. Companies such as API, a European company located in Italy, cooperate to avoid electric shock with high no-load voltage. However, when gloves are wet or welders are in contact with the surface of metal conductors, the original insulation layer will fail, resulting in electric shock

development history of Jinan assaying in the process of tungsten argon arc welding, high frequency is used for arc ignition or arc stabilization of AC arc. The duration of high frequency is milliseconds, the current is also very small, but the voltage is thousands of volts. In general, it will not cause electric shock, but sometimes high frequencies will accumulate on the skin surface, such as small and deep burns through the holes of gloves. The effects of high frequency on human nervous system have also been reported. In addition, the electromagnetic radiation generated by high frequency will interfere with the work of the instrument or equipment control system

1.2 arc radiation

welding arc can produce three types of radiation, namely ultraviolet, visible and infrared (thermal) radiation. The ways of harm to welders are: ultraviolet light will burn the skin and cause electro-optic ophthalmia; Visible light makes eyes dizzy and visual impairment; Infrared light is harmful to skin and eyes

at the work site, attention must be paid to the direct irradiation of arc light and the surface reflection through other objects at the same time. During the arc welding operation, the welder must select appropriate filter lenses and masks, and wear special work clothes for welding to avoid skin exposure

1.3 noise

different noise sources will appear on the welding production site, such as grinding of grooves, hammering during assembly, weld repair, plasma cutting, etc. on the production site, when the operator works for 8h with 90dB noise, it will be harmful to the hearing and nervous system. For example, the noise of manual grinding is 108db. Generally, when the noise exceeds the allowable value dB, it will have a harmful impact on the welder

1.4 soot

substances in gaseous and particulate states harmful to health are produced in the process of welding and related processes, including gas, smoke, dust and other welding soot. The particle size of welding soot is shown in Figure 1. The inhalable part (especially less than 3 μ Particles of M) will invade into the depths of the lungs, so it is more harmful. The short-term effects on health are respiratory tract irritation, cough, chest tightness, low fever caused by metal vapor, and acute flu symptoms; The long-term effects are iron deposition and benign tumors in the lungs, but no direct evidence of lung cancer has been found

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