Then the oxidation rate increases and it become easier to burn. Dust explosion requires three conditions: dust concentration, combustion substances and temperatures. Dusts of different substances have different explosive concentration. The concentration of manganese powder explosion is 210g/m3. The combustion substances refer to the concentration of oxygen. The temperature involves in lowest temperature that flame or spark burst the dust. So preventing burning occurrences should take the above three aspects into account.
Burning three conditions, that is a combustible material, oxidizing substances and sources of ignition. Fire, to stop the burning, that is to eliminate the burning conditions. Fire fighting in general there are three ways: the suffocation method is to remove the combustion material and a source of ignition; isolation, limit and stop the combustible material into the combustion zone; cooling method is to reduce the combustion temperature, to lower the temperature below the ignition point of combustible material . Manganese powder ignition point of 450 ° C, extinguish the burning manganese powder is suitable to use suffocation method and the isolation method.
Fire-fighting operation was gently cover the first use of asbestos in the fire source, and then dry powder fire extinguishing material scattered in the asbestos was on, until the flame goes out. In order to prevent the fire from spreading and to avoid the mixture of gas and dust explosion, fire fighting, and not to cause dust flying, and not to break the windows to avoid the formation. The product equipped with a container should be immediately transferred to safe areas. Body on fire, can not run around to quickly take off their clothes or asbestos was woolen been extinguished. Equipment or indoor fire, to immediately stop the operation of equipment, turn off all valves and fire fighting.
Plant domestic demand flare up, you should first flare location and environment to thoroughly clean equipment flare, the first device blowing clean, local removable parts should be detached and sent to a place of safety flare up and can not demolition or difficult to demolition must be before and after the flare site, disconnect the equipment system or partition isolation. Flare prepares a good and adequate fire fighting tools and materials. It develops effective fire prevention measures.
Manganese is one of the human body essential trace elements. Manganese uptake by the human body is absorbed in the intestine, mainly in the muscles, internal organs and brain. Manganese is the composition of the human variety of enzymes, play an important role in cell metabolism, Mn deficiency caused by osteoporosis, bone deformities, cartilage damage, such as lesions, but excessive intake of the body on the body to cause harm, cause poisoning. The clinical manifestations of manganese poisoning: light neurasthenia disease and autonomic dysfunction may be drowsiness, insomnia, headache, fatigue, memory loss and other symptoms. Irritability in some patients, nausea, and salivation increased loss of libido, sweating, numbness or pain, legs weakness. Low weight by language, manners slow, indifferent feelings or impulses. It often accompanied by psychiatric symptoms.
Therefore, metal powder supplier must be prepared to do labor protection and sanitation works. The specific practices are: the place which produces manganese dust needs control measures. The manganese dust exposed jobs should use protective masks. In workplace, smoking and eating are limited. People who are suffering from e nervous organic diseases, obviously neurasthenia syndrome, psychiatric, endocrine diseases will not be hired for the positions. At the same time
Burning three conditions, that is a combustible material, oxidizing substances and sources of ignition. Fire, to stop the burning, that is to eliminate the burning conditions. Fire fighting in general there are three ways: the suffocation method is to remove the combustion material and a source of ignition; isolation, limit and stop the combustible material into the combustion zone; cooling method is to reduce the combustion temperature, to lower the temperature below the ignition point of combustible material . Manganese powder ignition point of 450 ° C, extinguish the burning manganese powder is suitable to use suffocation method and the isolation method.
Fire-fighting operation was gently cover the first use of asbestos in the fire source, and then dry powder fire extinguishing material scattered in the asbestos was on, until the flame goes out. In order to prevent the fire from spreading and to avoid the mixture of gas and dust explosion, fire fighting, and not to cause dust flying, and not to break the windows to avoid the formation. The product equipped with a container should be immediately transferred to safe areas. Body on fire, can not run around to quickly take off their clothes or asbestos was woolen been extinguished. Equipment or indoor fire, to immediately stop the operation of equipment, turn off all valves and fire fighting.
Plant domestic demand flare up, you should first flare location and environment to thoroughly clean equipment flare, the first device blowing clean, local removable parts should be detached and sent to a place of safety flare up and can not demolition or difficult to demolition must be before and after the flare site, disconnect the equipment system or partition isolation. Flare prepares a good and adequate fire fighting tools and materials. It develops effective fire prevention measures.
Manganese is one of the human body essential trace elements. Manganese uptake by the human body is absorbed in the intestine, mainly in the muscles, internal organs and brain. Manganese is the composition of the human variety of enzymes, play an important role in cell metabolism, Mn deficiency caused by osteoporosis, bone deformities, cartilage damage, such as lesions, but excessive intake of the body on the body to cause harm, cause poisoning. The clinical manifestations of manganese poisoning: light neurasthenia disease and autonomic dysfunction may be drowsiness, insomnia, headache, fatigue, memory loss and other symptoms. Irritability in some patients, nausea, and salivation increased loss of libido, sweating, numbness or pain, legs weakness. Low weight by language, manners slow, indifferent feelings or impulses. It often accompanied by psychiatric symptoms.
Therefore, metal powder supplier must be prepared to do labor protection and sanitation works. The specific practices are: the place which produces manganese dust needs control measures. The manganese dust exposed jobs should use protective masks. In workplace, smoking and eating are limited. People who are suffering from e nervous organic diseases, obviously neurasthenia syndrome, psychiatric, endocrine diseases will not be hired for the positions. At the same time
LSAW steel pipe and SSAW steel pipe
2018年12月3日 乗り物LSAW steel pipe and SSAW steel pipe are important production processes in the national production and construction. They have many differences, such as material properties, production processes, and features. Here’s a specific introduction:
1. the metallurgical properties of materials: LSAW pipe is produced with steel plate, and spiral welded pipe is produced with hot rolled coil. The rolling process of the hot strip mill unit has a series of advantages, and has the metallurgical process capability to obtain high quality pipeline steel. For example, a water cooling system is installed on the output stage to accelerate cooling, which allows the use of low-alloy compositions to achieve special strength levels and low temperature toughness, thereby improving the weldability of the steel. However, this system is basically absent from the steel plate production plant. Coil alloy content (carbon equivalent) is often lower than similar grades of steel, which also improves the weldability of spiral welded pipe. It should be noted that since the spiral rolling direction of the spiral welded pipe is not perpendicular to the axial direction of the steel pipe (the solution depends on the helix angle of the steel pipe), the steel plate rolling direction of the straight seam steel pipe is perpendicular to the axial direction of the steel pipe. Thus, the spiral Welded pipe material has better crack resistance than straight seam steel pipe.
2. welding process: from the welding process, spiral welded pipe and straight seam steel pipe welding method is the same, but the straight seam welded pipe inevitably there will be a lot of T-welding, so there is a great increase in the probability of welding defects, and T-welding The welding residual stress at the seam is large, and the weld metal is often in a three-dimensional stress state, increasing the possibility of cracking. Moreover, according to the submerged-arc welding process specification, each weld should have an arc striking point and an arc extinguishing point. However, each straight-seam welding pipe cannot achieve this condition when welding a circumferential ring, and thus may have an arc extinguishing position. More welding defects.
Straight seam welded pipe production process is relatively simple, the main production processes are high-frequency welding straight seam welded pipe and submerged arc welded straight seam welded pipe. Longitudinal seam welded pipe has high production efficiency, low cost and rapid development. The strength of spiral welded pipes is generally higher than that of longitudinal welded pipes. The main production process is submerged arc welding. Spiral welded pipes can produce pipes with different diameters from the same width of blanks, and narrower blanks can also be used to produce larger diameter pipes. However, compared with the longitudinal welded pipe of the same length, the weld length is increased by 30 to 100% and the production speed is low. Therefore, the smaller diameter welded pipe mostly adopts the straight seam welding, and the large diameter welded pipe adopts the spiral welding.
3. Strength characteristics: When the tube is subjected to internal pressure, it usually produces two main stresses on the tube wall, namely radial stress δY and axial stress δX. Weld seam synthetic stress δ = δY (l/4sin2α cos2α) 1/2, where α is the spiral angle of the spiral welded pipe weld. The helix angle of the spiral welded pipe weld is generally 50-75 degrees, so the synthetic stress at the spiral welded joint is 60-85% of the principal stress of the longitudinal welded pipe. At the same working pressure, the spiral welded pipe with the same pipe diameter can be reduced in wall thickness than the straight welded pipe.
Therefore, the designer can use different welding techniques according to the specific conditions in the production process to meet the customer’s requirements.
1. the metallurgical properties of materials: LSAW pipe is produced with steel plate, and spiral welded pipe is produced with hot rolled coil. The rolling process of the hot strip mill unit has a series of advantages, and has the metallurgical process capability to obtain high quality pipeline steel. For example, a water cooling system is installed on the output stage to accelerate cooling, which allows the use of low-alloy compositions to achieve special strength levels and low temperature toughness, thereby improving the weldability of the steel. However, this system is basically absent from the steel plate production plant. Coil alloy content (carbon equivalent) is often lower than similar grades of steel, which also improves the weldability of spiral welded pipe. It should be noted that since the spiral rolling direction of the spiral welded pipe is not perpendicular to the axial direction of the steel pipe (the solution depends on the helix angle of the steel pipe), the steel plate rolling direction of the straight seam steel pipe is perpendicular to the axial direction of the steel pipe. Thus, the spiral Welded pipe material has better crack resistance than straight seam steel pipe.
2. welding process: from the welding process, spiral welded pipe and straight seam steel pipe welding method is the same, but the straight seam welded pipe inevitably there will be a lot of T-welding, so there is a great increase in the probability of welding defects, and T-welding The welding residual stress at the seam is large, and the weld metal is often in a three-dimensional stress state, increasing the possibility of cracking. Moreover, according to the submerged-arc welding process specification, each weld should have an arc striking point and an arc extinguishing point. However, each straight-seam welding pipe cannot achieve this condition when welding a circumferential ring, and thus may have an arc extinguishing position. More welding defects.
Straight seam welded pipe production process is relatively simple, the main production processes are high-frequency welding straight seam welded pipe and submerged arc welded straight seam welded pipe. Longitudinal seam welded pipe has high production efficiency, low cost and rapid development. The strength of spiral welded pipes is generally higher than that of longitudinal welded pipes. The main production process is submerged arc welding. Spiral welded pipes can produce pipes with different diameters from the same width of blanks, and narrower blanks can also be used to produce larger diameter pipes. However, compared with the longitudinal welded pipe of the same length, the weld length is increased by 30 to 100% and the production speed is low. Therefore, the smaller diameter welded pipe mostly adopts the straight seam welding, and the large diameter welded pipe adopts the spiral welding.
3. Strength characteristics: When the tube is subjected to internal pressure, it usually produces two main stresses on the tube wall, namely radial stress δY and axial stress δX. Weld seam synthetic stress δ = δY (l/4sin2α cos2α) 1/2, where α is the spiral angle of the spiral welded pipe weld. The helix angle of the spiral welded pipe weld is generally 50-75 degrees, so the synthetic stress at the spiral welded joint is 60-85% of the principal stress of the longitudinal welded pipe. At the same working pressure, the spiral welded pipe with the same pipe diameter can be reduced in wall thickness than the straight welded pipe.
Therefore, the designer can use different welding techniques according to the specific conditions in the production process to meet the customer’s requirements.
