Abstract: Valves have an irreplaceable role in production activities. Therefore, the valve is an important part and plays a very important role. The operation of the valve will directly affect the stable production of the equipment. Analyze some common faults in valve operation and improve them by corresponding means and methods, which can greatly improve the utilization of valves and greatly reduce the failure rate. The use of the valve control process will greatly increase production efficiency and economic efficiency, and can well control and save energy consumption.
Keywords: valve; failure analysis; maintenance strategy 1. Common valves and common problems in use In the chemical industry, valves are important accessories for controlling the flow of media in chemical pipelines. It is mainly used to cut off the flow of fluid in the pipeline and regulate the flow in the pipeline. According to their use, chemical valves can be divided into five categories, namely, shut-off valves, control valves, diverter valves, check valves and safety valves. Among them, the shut-off valve is mainly used to cut or connect the medium flow, including gate valve, globe valve, diaphragm valve, ball valve, plug valve, butterfly valve, plunger valve, ball valve and needle valve. The regulating valve is mainly used to adjust the medium flow, pressure, etc., including regulating valves, throttle valves, pressure reducing valves, and the like. Check valves are used to prevent backflow of media, including various types of check valves. Shunt valves are used to separate, distribute or mix media, including various dispensing valves and traps. Medium pressure safety protection safety valves, including various types of safety valves. According to its role, it can be divided into manual action valve and automatic action valve. Chemical valves must be inspected before use, including five aspects: check for internal and external surfaces of the valve for defects such as trachoma and cracks; check that the seat and valve body joints are secure, that the valve plug matches the valve seat, and whether the sealing surface is Defective; check the connection between the stem and the valve plug, whether the stem is bent, the thread is not damaged or corroded; check the package, the gasket is damaged due to aging; check the valve switch for flexibility.
2. Valve common faults 2.1 Flange and thread leakage at the valve and pipe joints Flange and threaded links at the valve and pipe joints are loose, which can easily lead to packing leakage. In the chemical industry, linear flow valves are commonly used, which have low flow resistance characteristics. In addition, valves that are normally closed and opened are preferred because they are easy to regulate flow. Regarding the use of valves to control flow, ball and plug valves are suitable for steering. Still another type of valve can be used as a wiper that seals along the sealing surface for aerosol applications. We often see the use of more chemical valves, including globe valves, ball valves, safety valves, check valves and plug valves.
2.2 External damage External damage due to material defects. The valve manufacturing process is very complicated. If the valve is cast with voids or inclusions, these defects may increase the likelihood of damage and cause liquid leakage during use. The function of the valve is mainly to control the flow state of the fluid. The valve is throttled under high pressure. Due to the influence of the gas, the throttle position of the valve is likely to cause cavitation, which may cause damage to the valve. Finally, when the valve controls the flow of fluid, the valve will also withstand high pressure and will be damaged. As the temperature changes, the amount of gas in the pipe changes, the temperature rises, and the amount of gas increases, thereby increasing the gas pressure in the pipe. This will also cause some damage to the valve. If the temperature is too high, exceeding the heat resistance of the valve may cause the valve to rupture and may cause the valve to wear faster and cause damage.
2.3 Internal wear When controlling fluid, the valve flap directly acts as a throttle valve, and the valve flap is relatively easy to wear. At this time, if there is a pressure difference between the fluids on both sides of the disc, a problem of valve leakage occurs, and the leakage accelerates the wear of the valve. Fluid can block the flow of the valve. When the scale is peeled off, the valve will be worn, and long-term accumulation will cause greater damage, causing the valve to leak.
2.4 Valve Switch Failure Under normal conditions, the valve switch will fail under the following conditions. The first is the failure to damage the operating rod thread; the second is the lack of lubricant that makes the valve difficult to switch; the third is the bending rod failure; the fourth is the lack of dry surface cleanliness is insufficient; the fifth is between the moving parts of the valve tolerance The bite is too tight.
2.5 The main causes of vibration vibration are as follows: first is the incorrect valve operation; the second is the excess fluid flowing through the valve. The reason for the excessive flow is that the valve is not properly selected, and the flow under normal conditions exceeds the rated flow of the valve. When selected, the rated flow of the valve should be greater than the design flow of the pipe. The third is the diameter of the valve inlet tube. If the valve is too large and the valve diameter is small, the larger inlet resistance of the valve will cause the valve to vibrate. This requires an appropriate increase in the resistance of the discharge pipe to control the tremor.
3. Valve monitoring 3.1 Problems in valve fault monitoring With the advancement of China's science and technology and the development of industry, all walks of life rely more and more on mechanical products. At the same time, the safety requirements for mechanical products are getting higher and higher and more and more strict. At the same time, the continuous development of mechanical products has become more and more complicated, and the factors affecting their failure have become complicated, and the losses caused by their failures have also increased. Therefore, system analysis of mechanical failures, especially valve failures, is critical. The current fault monitoring has the following problems: the valve selection monitoring is not in place, the valve quality is not paid attention when selecting the valve, and the poor quality of the selected valve leads to short service life, which is not conducive to improving work efficiency; according to the use situation, it is forbidden to monitor the valve during use. In case of use, the valve is seriously damaged; valve maintenance and monitoring work is not in place. If the valve is damaged during maintenance, the system will be damaged.
3.2 On-site valve fault monitoring and effective troubleshooting measures There are two valve faults: sudden failure and gradual failure. We mainly study the on-site valve failure, which is a sudden failure. The failure of the valve is mainly a production failure, that is to say, in the production process, the production process of the valve is not strictly followed, resulting in failure. The other is structural failure, which is caused by a series of problems in the valve design. Failure to operate means that the valve is not used based on its operating conditions and associated procedures. In addition, some component failures may cause some problems. Therefore, we should also pay attention to these aspects when monitoring. It monitors the production process, monitors the operation process, monitors the quality and use of the valve, and monitors the major components of the valve that are prone to problems.
3.2.1 Production Process Monitoring In the production process, employees must strictly follow the valve production process. However, the monitoring of the valve production process is not part of the valve user control, but a place that valve manufacturers need to pay attention to. The part that the valve user can control is the control of the valve selection. When the valve user selects the valve, the quality priority principle must be strictly followed, and the valve with poor quality or relatively poor quality cannot be selected for cost saving.
3.2.2 Monitoring the use of the valve The valve will experience aging, corrosion and other phenomena during the production process, we must monitor its use in real time. This part is mainly divided into two parts. Part of it is to arrange for professionals to regularly inspect and maintain valves, and to regularly maintain valves to identify problems, solve problems, and prevent malfunctions. On the other hand, it is mainly the data management of valves, the use of information technology and the development of big data, and strengthen the comprehensive analysis of valve indicators to prevent problems and prevent failures.
4. Valve maintenance measures 4.1 Regular lubrication During the process of adding fat, care should be taken to control the quality of fatliquoring. The operator must use the correct fatliquoring method for fatliquoring. Determine the amount of fat based on the size and type of valve and add the appropriate grease. During the fatliquoring process, it is necessary to control the fatliquoring pressure and pay attention to the change in fatliquoring pressure. If the grease pressure is too low, the seal will fail or leak, causing the seal to become clogged. If the fat pressure is too high, check the fatliquoring process. If there is a problem such as grease blockage, it must be replaced; if the ester hardens, it must be cleaned with a detergent, gradually soften the defective sealant, and then replace it with a new one.
4.2 Maintenance of the filler Under normal conditions, no leakage test is the basic requirement for filling. After the valve is installed in the pipe, problems such as leakage may occur due to various factors such as temperature. At this point, we must pay attention to tighten the nuts on both sides of the packing gland to prevent the elastic failure of the packing and reduce the sealing performance of the packing. Some fillers contain a certain amount of molybdenum dioxide lubricant and should be added after a few months of use. If the filler is found to be insufficient, it must be added in time to ensure the seal of the entire valve.
5. Summary Valves play an important role in all walks of life. Once the valve fails, it will cause considerable economic and other losses in production activities. Even if a valve is present, valve monitoring can effectively avoid valve problems to a certain extent. The problem can also be timely and effective measures. Therefore, the valve needs to be monitored during the production process. At the same time, however, valve fault monitoring must also be effective. In order to monitor on-site valve failures, we must take effective troubleshooting measures to prevent real-time failures.
references:
[1] Dong Yuenong. The Fourth Wave of Light Weapons Equipment: Fire Fighting Individual System [M]. Beijing: National Defence Industry Press, 2006.
Keywords: valve; failure analysis; maintenance strategy 1. Common valves and common problems in use In the chemical industry, valves are important accessories for controlling the flow of media in chemical pipelines. It is mainly used to cut off the flow of fluid in the pipeline and regulate the flow in the pipeline. According to their use, chemical valves can be divided into five categories, namely, shut-off valves, control valves, diverter valves, check valves and safety valves. Among them, the shut-off valve is mainly used to cut or connect the medium flow, including gate valve, globe valve, diaphragm valve, ball valve, plug valve, butterfly valve, plunger valve, ball valve and needle valve. The regulating valve is mainly used to adjust the medium flow, pressure, etc., including regulating valves, throttle valves, pressure reducing valves, and the like. Check valves are used to prevent backflow of media, including various types of check valves. Shunt valves are used to separate, distribute or mix media, including various dispensing valves and traps. Medium pressure safety protection safety valves, including various types of safety valves. According to its role, it can be divided into manual action valve and automatic action valve. Chemical valves must be inspected before use, including five aspects: check for internal and external surfaces of the valve for defects such as trachoma and cracks; check that the seat and valve body joints are secure, that the valve plug matches the valve seat, and whether the sealing surface is Defective; check the connection between the stem and the valve plug, whether the stem is bent, the thread is not damaged or corroded; check the package, the gasket is damaged due to aging; check the valve switch for flexibility.
2. Valve common faults 2.1 Flange and thread leakage at the valve and pipe joints Flange and threaded links at the valve and pipe joints are loose, which can easily lead to packing leakage. In the chemical industry, linear flow valves are commonly used, which have low flow resistance characteristics. In addition, valves that are normally closed and opened are preferred because they are easy to regulate flow. Regarding the use of valves to control flow, ball and plug valves are suitable for steering. Still another type of valve can be used as a wiper that seals along the sealing surface for aerosol applications. We often see the use of more chemical valves, including globe valves, ball valves, safety valves, check valves and plug valves.
2.2 External damage External damage due to material defects. The valve manufacturing process is very complicated. If the valve is cast with voids or inclusions, these defects may increase the likelihood of damage and cause liquid leakage during use. The function of the valve is mainly to control the flow state of the fluid. The valve is throttled under high pressure. Due to the influence of the gas, the throttle position of the valve is likely to cause cavitation, which may cause damage to the valve. Finally, when the valve controls the flow of fluid, the valve will also withstand high pressure and will be damaged. As the temperature changes, the amount of gas in the pipe changes, the temperature rises, and the amount of gas increases, thereby increasing the gas pressure in the pipe. This will also cause some damage to the valve. If the temperature is too high, exceeding the heat resistance of the valve may cause the valve to rupture and may cause the valve to wear faster and cause damage.
2.3 Internal wear When controlling fluid, the valve flap directly acts as a throttle valve, and the valve flap is relatively easy to wear. At this time, if there is a pressure difference between the fluids on both sides of the disc, a problem of valve leakage occurs, and the leakage accelerates the wear of the valve. Fluid can block the flow of the valve. When the scale is peeled off, the valve will be worn, and long-term accumulation will cause greater damage, causing the valve to leak.
2.4 Valve Switch Failure Under normal conditions, the valve switch will fail under the following conditions. The first is the failure to damage the operating rod thread; the second is the lack of lubricant that makes the valve difficult to switch; the third is the bending rod failure; the fourth is the lack of dry surface cleanliness is insufficient; the fifth is between the moving parts of the valve tolerance The bite is too tight.
2.5 The main causes of vibration vibration are as follows: first is the incorrect valve operation; the second is the excess fluid flowing through the valve. The reason for the excessive flow is that the valve is not properly selected, and the flow under normal conditions exceeds the rated flow of the valve. When selected, the rated flow of the valve should be greater than the design flow of the pipe. The third is the diameter of the valve inlet tube. If the valve is too large and the valve diameter is small, the larger inlet resistance of the valve will cause the valve to vibrate. This requires an appropriate increase in the resistance of the discharge pipe to control the tremor.
3. Valve monitoring 3.1 Problems in valve fault monitoring With the advancement of China's science and technology and the development of industry, all walks of life rely more and more on mechanical products. At the same time, the safety requirements for mechanical products are getting higher and higher and more and more strict. At the same time, the continuous development of mechanical products has become more and more complicated, and the factors affecting their failure have become complicated, and the losses caused by their failures have also increased. Therefore, system analysis of mechanical failures, especially valve failures, is critical. The current fault monitoring has the following problems: the valve selection monitoring is not in place, the valve quality is not paid attention when selecting the valve, and the poor quality of the selected valve leads to short service life, which is not conducive to improving work efficiency; according to the use situation, it is forbidden to monitor the valve during use. In case of use, the valve is seriously damaged; valve maintenance and monitoring work is not in place. If the valve is damaged during maintenance, the system will be damaged.
3.2 On-site valve fault monitoring and effective troubleshooting measures There are two valve faults: sudden failure and gradual failure. We mainly study the on-site valve failure, which is a sudden failure. The failure of the valve is mainly a production failure, that is to say, in the production process, the production process of the valve is not strictly followed, resulting in failure. The other is structural failure, which is caused by a series of problems in the valve design. Failure to operate means that the valve is not used based on its operating conditions and associated procedures. In addition, some component failures may cause some problems. Therefore, we should also pay attention to these aspects when monitoring. It monitors the production process, monitors the operation process, monitors the quality and use of the valve, and monitors the major components of the valve that are prone to problems.
3.2.1 Production Process Monitoring In the production process, employees must strictly follow the valve production process. However, the monitoring of the valve production process is not part of the valve user control, but a place that valve manufacturers need to pay attention to. The part that the valve user can control is the control of the valve selection. When the valve user selects the valve, the quality priority principle must be strictly followed, and the valve with poor quality or relatively poor quality cannot be selected for cost saving.
3.2.2 Monitoring the use of the valve The valve will experience aging, corrosion and other phenomena during the production process, we must monitor its use in real time. This part is mainly divided into two parts. Part of it is to arrange for professionals to regularly inspect and maintain valves, and to regularly maintain valves to identify problems, solve problems, and prevent malfunctions. On the other hand, it is mainly the data management of valves, the use of information technology and the development of big data, and strengthen the comprehensive analysis of valve indicators to prevent problems and prevent failures.
4. Valve maintenance measures 4.1 Regular lubrication During the process of adding fat, care should be taken to control the quality of fatliquoring. The operator must use the correct fatliquoring method for fatliquoring. Determine the amount of fat based on the size and type of valve and add the appropriate grease. During the fatliquoring process, it is necessary to control the fatliquoring pressure and pay attention to the change in fatliquoring pressure. If the grease pressure is too low, the seal will fail or leak, causing the seal to become clogged. If the fat pressure is too high, check the fatliquoring process. If there is a problem such as grease blockage, it must be replaced; if the ester hardens, it must be cleaned with a detergent, gradually soften the defective sealant, and then replace it with a new one.
4.2 Maintenance of the filler Under normal conditions, no leakage test is the basic requirement for filling. After the valve is installed in the pipe, problems such as leakage may occur due to various factors such as temperature. At this point, we must pay attention to tighten the nuts on both sides of the packing gland to prevent the elastic failure of the packing and reduce the sealing performance of the packing. Some fillers contain a certain amount of molybdenum dioxide lubricant and should be added after a few months of use. If the filler is found to be insufficient, it must be added in time to ensure the seal of the entire valve.
5. Summary Valves play an important role in all walks of life. Once the valve fails, it will cause considerable economic and other losses in production activities. Even if a valve is present, valve monitoring can effectively avoid valve problems to a certain extent. The problem can also be timely and effective measures. Therefore, the valve needs to be monitored during the production process. At the same time, however, valve fault monitoring must also be effective. In order to monitor on-site valve failures, we must take effective troubleshooting measures to prevent real-time failures.
references:
[1] Dong Yuenong. The Fourth Wave of Light Weapons Equipment: Fire Fighting Individual System [M]. Beijing: National Defence Industry Press, 2006.
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