Causes, harmfulness and preventive measures of the

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Causes, harmfulness and preventive measures of oxygen cylinder explosion

welding technology is an important processing technology in modern industrial production, and is widely used in many production departments such as chemical industry and machinery manufacturing. The welding and gas cutting of metals require oxygen. Except that the oxygen can be transported by pipeline from the manufacturer to the user. Most of it is contained in oxygen cylinders. The oxygen contained in the cylinders usually maintains a pressure of 150 kgf/cm ^ 2. Because the pure oxygen contained in the cylinders is a strong oxidant, improper handling and use during the welding operation will often lead to explosion and combustion accidents. For example, on July 11, 1990, Shandong Linyi Pingshang glass factory had an accident in which spare parts should be used to make up for the explosion of oxygen cylinders due to improper operation and use, killing two people and seriously injuring one person on the spot

I. common causes of oxygen cylinder explosion and combustion

(I) accidents caused by improper filling. The correct filling of gas cylinders is the key link to ensure the safe use of gas cylinders. Explosion accidents often occur due to improper filling. The most dangerous factor in this aspect is the filling of oxygen with cylinders that have been filled with combustible gases (such as hydrogen) and the overfilling of oxygen

(II) the material and manufacturing quality of the gas cylinder do not meet the requirements. In the process of filling and using oxygen, explosion accidents often occur, which are mainly manifested in the fragile materials for making gas cylinders, uneven thickness of the cylinder wall, interlayer of the cylinder body, etc

(III) accidents caused by improper maintenance and storage of gas cylinders. The main reason is that the cylinder body is seriously corroded, or the cylinder is exposed to the sun for a long time in use, or the cylinder is close to a high-temperature heat source, which is the common direct cause of cylinder explosion. According to the test, the temperature of the oxygen cylinder wall can reach 200 ℃ under the direct exposure of the sun in midsummer. Generally, the condition for filling oxygen is that the temperature is 20 ℃ and the pressure is 150 atmospheric pressure. The air pressure in the bottle increases with the increase of temperature, which can be calculated by the following formula: P = 150 × 273 + T/273 + 20 (where p is the bottle pressure and t is the bottle temperature)

(IV) improper operation of gas cylinders will also lead to accidents such as fire or burning of gas cylinder accessories. This is mainly reflected in two aspects. First, when opening the cylinder valve of the oxygen cylinder, because it is opened too fast, the pressure in the pressure reducer or pipeline will increase rapidly, and the temperature will also increase greatly. In serious cases, the rubber gasket and other accessories will be burned; On the other hand, compared with the past, the plastic material of Meilan 3 has smaller density and higher strength, and the gas opening speed is too fast. Because the gas contains water droplets, rust and other particles (the oxygen purity used for gas welding and gas cutting is generally grade I and grade II, the oxygen content of grade I purity is not less than 99.2%, and the oxygen content of grade II purity is not less than 98.5%), static sparks are generated when flowing through the bottle valve at high speed, causing combustion or explosion

(V) the cylinder valve is not protected by the cylinder cap, vibrated or improperly used, resulting in loose sealing, leakage, and even damage to the cylinder valve, causing high-pressure air flow to rush out and cause combustion and explosion

(VI) the cylinder valve or other accessories (such as valve rod and pressure reducer) are stained with grease, which often leads to fire and combustion accidents

second, the harm of oxygen cylinder combustion and explosion

oxygen cylinder combustion and explosion caused by the above reasons, its destructive power is quite large. As mentioned above, the oxygen bottle is a high-pressure container, and it needs to be filled with 2 oxygen with high friction and short service life, and the pressure is 150 atmospheric pressure. At the same time, it also needs to bear the external forces such as vibration, rolling and collision impact during handling. Bottled oxygen is a strong oxidant. Once a combustion and explosion accident occurs, its destructive power is quite large. For example, when a unit transports oxygen cylinders with a trailer and unloads them, it bumps one cylinder onto another, causing both cylinders to explode at the same time. The fragments of the gas cylinder flew out (the farthest 200 meters), and the wall of the warehouse was pierced, with the largest hole of about 1000 × 800 mm, causing an injury accident

explosion, in a broad sense, refers to an extremely rapid, physical or chemical energy release process. When the pressure vessel breaks, the high-pressure gas in the vessel relieves the restriction of the shell, expands rapidly and releases energy at a high speed. On the one hand, the broken fragments of the container fly around at a high speed, causing casualties or damaging the surrounding equipment; On the other hand, a larger part of it does work on the surrounding air and generates shock waves. In addition to directly causing casualties, it may also destroy buildings such as factories and have a greater destructive effect

when the oxygen cylinder explodes, the debris flying out at high speed will cause casualties if it hits the human body. When the kinetic energy of debris is more than 2.6kgf · m, it can cause human injury; When the kinetic energy reaches more than 6.0kgf · m, it can cause minor injuries to human bones; When it exceeds 20kgf · m, it can cause serious injury or even death to human bones. The kinetic energy (E) produced by the fragment is in direct proportion to the mass (m) of the fragment and the square of the flying speed (V) when the cylinder is broken, which can be calculated by the following formula: e = 1/2mV ^ 2 = 1/2 × (w/g) × V ^ 2 (where W is the weight of debris and G is the acceleration of gravity, taking 9.8 m/s)

in addition, when the gas cylinder explodes, if the fragments fall on the container containing dangerous chemicals, it may cause the leakage of dangerous substances, and even explosion, combustion, poisoning accidents, causing more serious damage

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