There are two kinds of regulating valve repairs: First, preventive maintenance, mainly refers to the preventive maintenance measures taken to ensure the reliable operation of the regulating valve, and in the absence of failure, including the adjustment valve in the field when installed and used Series of preventive measures; Second, faulty maintenance, that is, a series of maintenance work conducted when the regulating valve fails to meet operating requirements in the event of a fault. Generally, it is completed in the production workshop. Under special circumstances, the pipeline may be directly repaired. .
1 Preventive maintenance
Preventive maintenance is planned maintenance prior to failure of the regulating valve. It can be understood as routine maintenance and usually includes the following tasks.
1.1 Eliminate stress
Improper combination or improper installation of pipelines can cause various stresses, such as thermal stress caused by high-temperature medium, stress caused by unbalanced fastening force during installation, and stress caused by man-made collisions to control valves and pipelines. These stresses act on the regulating valve and its pipeline, and it is easy to affect the performance of the regulating valve. When it is serious, it will affect the regulating system itself, causing the valve stem and the guide element to deform and cannot align with the valve seat center; for the split valve The body's regulating valve may cause the valve body flange to disengage; stress may also cause the valve seat to leak. Therefore, at all times, it must be ensured that stress is avoided or eliminated and the stress is directed away from the regulating valve.
1.2 check the support situation
The best position for installing the regulating valve is to make the stem stroke direction and the actuator above the valve body in a vertical plane. If the regulating valve must be installed in a position where the valve stem moves horizontally, or if the moving direction of the valve stem has a certain inclination with the horizontal plane, the actuator should be supported so that all parts of the regulating valve are in a natural state. If no additional support is provided or the support is incorrectly installed, misalignment between the valve stem and the valve seat may be caused, which can easily lead to differential or leakage of the filler. Even if the regulating valve has fixing and supporting measures, it must be checked regularly, usually 2 to 3 months.
1.3 Remove or prevent foreign matter from entering
Always check whether there is any rust, welding slag, dirt, etc. inside the connecting pipe of the regulating valve, and remove it immediately after discovery. If foreign matter is likely to accumulate in the regulating valve and pipe, consider installing a simple filter device on the upstream side of the regulating valve. Whenever it is easy to infiltrate hard materials in the process media, a permanent filter must be installed. Because the regulating valve is closed, a small piece of rust or welding slag is enough to damage the well-sealed valve seat sealing surface, and these contaminants will also cause wear on the regulator valve spool and valve seat, which will affect its normal operation.
1.4 Regularly check the air supply and power supply
Gas source is one of the key energy sources to drive the regulating valve. Although the air chamber of the pneumatic control valve does not consume air, if the air source system contains impurities such as moisture, oil, etc., the accessories such as the valve positioner and the relay may become clogged and fail. Therefore, the gas source and power supply must be checked regularly to ensure that the gas source is clean and dry and the power supply is reliable.
1.5 regular maintenance and refueling
Fillers and oilers need to be readjusted after a short period of use. For dusty occasions, use plastic sleeves or rubber sleeves around the valve stem to protect the stuffing box and guides. Special protective measures should be used in the presence of corrosive gas or liquid droplets. Generally, the anti-corrosion bag is used to wrap the regulating valve. Note that it cannot affect its operation. In the case where fire resistance is required, special fireproof coatings, fireproof bags, etc. may be used. The material of the fireproof bag contains multilayer ceramic fibers or glass fibers.
1.6 Transportation and Storage
After assembling and painting the valve, and fitting the actuator, hand wheel, positioner and other accessories as required, in order to prevent foreign substances from entering the regulating valve, all air interfaces connecting the regulating valve shall be plugged, and the connecting flange shall be equipped with a protective cover. , Pay attention to the status of each connection, such as the valve positioner intake manifold and actuator interface. Any protruding attachments that are easily damaged, such as pressure gauges for lubricators and potentiometers, should be removed from the fittings, packaged separately from the regulating valve and transported together. The control valve is fixed with special brackets to prevent loosening and to ensure the overall vertical or horizontal position. If transported long distances, it is best to use a solid wooden box shipment.
When storing the regulator valve, do not support the regulator valve at sensitive locations, such as valve positioners, valve stems, etc. The environmental conditions for transportation and storage should meet the requirements of the product specification. It is best not to perform other operations in the storage area. When it is unavoidable, care must be taken not to touch the regulator. Sites should also be protected from the harsh conditions of sand, dust, rain, etc. If there is no suitable place, the regulator must be placed in a moisture-proof bag or placed in a similar container before storage.
1.7 Safe Operation Check
For the control valves and related accessories used in explosive hazardous locations, check their safe operation, such as whether the sealing cap is tightened, the operation status of the safety barrier, power supply, etc., to ensure that the regulating valve and related accessories can operate safely.
2Faulty maintenance
When the regulating valve cannot operate or does not meet the operating requirements, it means that there is a fault and the fault must be repaired. In the case of failure to determine the cause of the fault, generally follow the steps described below.
2.1 Cleaning
After removing the defective regulator from the pipeline, the first step in maintenance is to thoroughly clean the regulator. The regulating valve is easily contaminated by the process fluid. If the process medium is corrosive, explosive, or radioactive, it will harm the human body. The components soaked in the process media must be cleaned by special methods.
Cleaning methods vary with the nature of the process media. Under normal circumstances, as long as the water or steam can be purging, for certain pollution, such as alkaline medium pickling method, the heavy metal pollution will have special treatment at high temperatures, long time. Avoid repeated contamination during cleaning and proceed in a safe place. All cleaning tools such as containers, heating equipment, steam hoses, washing equipment, etc. must be prepared in advance.
2.2 Dismantling the regulating valve
When disassembling the regulating valve, the connection position of the actuator corresponding to the valve body should be marked. The actuator is separated from the upper valve cover and the upper valve cover is separated from the valve body. After the upper valve cover and the stuffing box component are disassembled, the valve body is removed from the valve body. Can remove the valve core, stem and other components. All disassembled parts and components must be carefully examined to determine which parts need to be repaired and replaced.
After the valve is disassembled, it is usually necessary to pay attention to the following parts during inspection: 1) The inner wall of the valve. Check its pressure resistance and corrosion resistance; 2) Valve seat. Due to the infiltration of the medium, the surface of the thread used for fixing the valve seat is easily corroded to loosen the valve seat. For high pressure applications, the corrosion or damage of the valve seat sealing surface should also be checked. Of course, in some structures, the valve seat and the valve body are not The use of threaded connection, but with a gasket pressed, but no matter which way is adopted, the seat of the valve seat and the seal of the body must focus on inspection; 3) spool. Should carefully check whether the valve core parts are corroded or worn out, especially if the valve core wears more seriously under high pressure difference, in addition, the valve stem must also check whether there is a similar situation, and if the connection with the valve core is loose, etc.; Seals and gaskets. Check whether the seal packing and gasket are aged, cracked, etc., and whether the mating surface is intact.
2.3 Dismantling the actuator
After disassembling the actuator, carefully inspect the bracket, diaphragm, spring, push rod and threaded connector, etc., wherein the bracket is a force member and can not have cracks; the diaphragm is a key component and cannot be damaged or aged; the spring can not be cracked, For multiple spring actuators, as long as one of the springs is damaged, the performance of the entire actuator will be seriously affected. No matter what kind of parts, once it is eroded or rusted, it is best to replace new parts.
2.4 Reassembly
Reassemble after all parts and components have been repaired. During the reassembly process, care should be taken to select the proper gaskets and bolt connections to accurately center and tighten evenly to prevent the flange from leaking. The torsional load of bolts or studs is related to its size and it is not allowed to overtighten. The type, quantity, and installation method of the fillers directly affect the sealing performance and cannot be taken lightly when assembling.
After re-assembling the actuator, suitable lubricants are also applied to the various frictional parts. These include stems and guides, actuator stems and guides, bearings, transmission parts, adjustment nuts, etc.
2.5 test
After reassembling, the regulating valve must be tested, such as basic performance test, air tightness test, leakage test, etc., and it can be sent to the site for installation after passing the test.
3 conclusions
Fault repair, also known as passive maintenance, is a maintenance method that is performed when a regulating valve fails. Because the equipment fails to repair, it often causes the production process to stop. In severe cases, equipment damage or casualties occur. Faulty repairs are undesirable during the production process. Preventive maintenance is based on past operating experience, during the installation and use process, in the case of failure of the regulator valve, a preventive maintenance method on the regulator valve on time, its purpose is to prevent accidents, People usually formulate corresponding fault prevention measures according to the different operating conditions of the regulating valve, and maintenance can be performed because the fault does not occur, which can greatly reduce the probability of fault occurrence.
In practical applications of regulating valves, preventive maintenance and fault repair are usually combined and used. The former is supplemented by the latter to maximize the effective service life of the regulating valve. Only in this way can the utilization efficiency of the regulating valve be improved. Reducing the system failure rate has practical and positive significance for the improvement of production process efficiency and economic efficiency as well as reduction of energy consumption. It can effectively improve the quality of the system's regulation and ensure the long-term, safe and efficient operation of production equipment.
1 Preventive maintenance
Preventive maintenance is planned maintenance prior to failure of the regulating valve. It can be understood as routine maintenance and usually includes the following tasks.
1.1 Eliminate stress
Improper combination or improper installation of pipelines can cause various stresses, such as thermal stress caused by high-temperature medium, stress caused by unbalanced fastening force during installation, and stress caused by man-made collisions to control valves and pipelines. These stresses act on the regulating valve and its pipeline, and it is easy to affect the performance of the regulating valve. When it is serious, it will affect the regulating system itself, causing the valve stem and the guide element to deform and cannot align with the valve seat center; for the split valve The body's regulating valve may cause the valve body flange to disengage; stress may also cause the valve seat to leak. Therefore, at all times, it must be ensured that stress is avoided or eliminated and the stress is directed away from the regulating valve.
1.2 check the support situation
The best position for installing the regulating valve is to make the stem stroke direction and the actuator above the valve body in a vertical plane. If the regulating valve must be installed in a position where the valve stem moves horizontally, or if the moving direction of the valve stem has a certain inclination with the horizontal plane, the actuator should be supported so that all parts of the regulating valve are in a natural state. If no additional support is provided or the support is incorrectly installed, misalignment between the valve stem and the valve seat may be caused, which can easily lead to differential or leakage of the filler. Even if the regulating valve has fixing and supporting measures, it must be checked regularly, usually 2 to 3 months.
1.3 Remove or prevent foreign matter from entering
Always check whether there is any rust, welding slag, dirt, etc. inside the connecting pipe of the regulating valve, and remove it immediately after discovery. If foreign matter is likely to accumulate in the regulating valve and pipe, consider installing a simple filter device on the upstream side of the regulating valve. Whenever it is easy to infiltrate hard materials in the process media, a permanent filter must be installed. Because the regulating valve is closed, a small piece of rust or welding slag is enough to damage the well-sealed valve seat sealing surface, and these contaminants will also cause wear on the regulator valve spool and valve seat, which will affect its normal operation.
1.4 Regularly check the air supply and power supply
Gas source is one of the key energy sources to drive the regulating valve. Although the air chamber of the pneumatic control valve does not consume air, if the air source system contains impurities such as moisture, oil, etc., the accessories such as the valve positioner and the relay may become clogged and fail. Therefore, the gas source and power supply must be checked regularly to ensure that the gas source is clean and dry and the power supply is reliable.
1.5 regular maintenance and refueling
Fillers and oilers need to be readjusted after a short period of use. For dusty occasions, use plastic sleeves or rubber sleeves around the valve stem to protect the stuffing box and guides. Special protective measures should be used in the presence of corrosive gas or liquid droplets. Generally, the anti-corrosion bag is used to wrap the regulating valve. Note that it cannot affect its operation. In the case where fire resistance is required, special fireproof coatings, fireproof bags, etc. may be used. The material of the fireproof bag contains multilayer ceramic fibers or glass fibers.
1.6 Transportation and Storage
After assembling and painting the valve, and fitting the actuator, hand wheel, positioner and other accessories as required, in order to prevent foreign substances from entering the regulating valve, all air interfaces connecting the regulating valve shall be plugged, and the connecting flange shall be equipped with a protective cover. , Pay attention to the status of each connection, such as the valve positioner intake manifold and actuator interface. Any protruding attachments that are easily damaged, such as pressure gauges for lubricators and potentiometers, should be removed from the fittings, packaged separately from the regulating valve and transported together. The control valve is fixed with special brackets to prevent loosening and to ensure the overall vertical or horizontal position. If transported long distances, it is best to use a solid wooden box shipment.
When storing the regulator valve, do not support the regulator valve at sensitive locations, such as valve positioners, valve stems, etc. The environmental conditions for transportation and storage should meet the requirements of the product specification. It is best not to perform other operations in the storage area. When it is unavoidable, care must be taken not to touch the regulator. Sites should also be protected from the harsh conditions of sand, dust, rain, etc. If there is no suitable place, the regulator must be placed in a moisture-proof bag or placed in a similar container before storage.
1.7 Safe Operation Check
For the control valves and related accessories used in explosive hazardous locations, check their safe operation, such as whether the sealing cap is tightened, the operation status of the safety barrier, power supply, etc., to ensure that the regulating valve and related accessories can operate safely.
2Faulty maintenance
When the regulating valve cannot operate or does not meet the operating requirements, it means that there is a fault and the fault must be repaired. In the case of failure to determine the cause of the fault, generally follow the steps described below.
2.1 Cleaning
After removing the defective regulator from the pipeline, the first step in maintenance is to thoroughly clean the regulator. The regulating valve is easily contaminated by the process fluid. If the process medium is corrosive, explosive, or radioactive, it will harm the human body. The components soaked in the process media must be cleaned by special methods.
Cleaning methods vary with the nature of the process media. Under normal circumstances, as long as the water or steam can be purging, for certain pollution, such as alkaline medium pickling method, the heavy metal pollution will have special treatment at high temperatures, long time. Avoid repeated contamination during cleaning and proceed in a safe place. All cleaning tools such as containers, heating equipment, steam hoses, washing equipment, etc. must be prepared in advance.
2.2 Dismantling the regulating valve
When disassembling the regulating valve, the connection position of the actuator corresponding to the valve body should be marked. The actuator is separated from the upper valve cover and the upper valve cover is separated from the valve body. After the upper valve cover and the stuffing box component are disassembled, the valve body is removed from the valve body. Can remove the valve core, stem and other components. All disassembled parts and components must be carefully examined to determine which parts need to be repaired and replaced.
After the valve is disassembled, it is usually necessary to pay attention to the following parts during inspection: 1) The inner wall of the valve. Check its pressure resistance and corrosion resistance; 2) Valve seat. Due to the infiltration of the medium, the surface of the thread used for fixing the valve seat is easily corroded to loosen the valve seat. For high pressure applications, the corrosion or damage of the valve seat sealing surface should also be checked. Of course, in some structures, the valve seat and the valve body are not The use of threaded connection, but with a gasket pressed, but no matter which way is adopted, the seat of the valve seat and the seal of the body must focus on inspection; 3) spool. Should carefully check whether the valve core parts are corroded or worn out, especially if the valve core wears more seriously under high pressure difference, in addition, the valve stem must also check whether there is a similar situation, and if the connection with the valve core is loose, etc.; Seals and gaskets. Check whether the seal packing and gasket are aged, cracked, etc., and whether the mating surface is intact.
2.3 Dismantling the actuator
After disassembling the actuator, carefully inspect the bracket, diaphragm, spring, push rod and threaded connector, etc., wherein the bracket is a force member and can not have cracks; the diaphragm is a key component and cannot be damaged or aged; the spring can not be cracked, For multiple spring actuators, as long as one of the springs is damaged, the performance of the entire actuator will be seriously affected. No matter what kind of parts, once it is eroded or rusted, it is best to replace new parts.
2.4 Reassembly
Reassemble after all parts and components have been repaired. During the reassembly process, care should be taken to select the proper gaskets and bolt connections to accurately center and tighten evenly to prevent the flange from leaking. The torsional load of bolts or studs is related to its size and it is not allowed to overtighten. The type, quantity, and installation method of the fillers directly affect the sealing performance and cannot be taken lightly when assembling.
After re-assembling the actuator, suitable lubricants are also applied to the various frictional parts. These include stems and guides, actuator stems and guides, bearings, transmission parts, adjustment nuts, etc.
2.5 test
After reassembling, the regulating valve must be tested, such as basic performance test, air tightness test, leakage test, etc., and it can be sent to the site for installation after passing the test.
3 conclusions
Fault repair, also known as passive maintenance, is a maintenance method that is performed when a regulating valve fails. Because the equipment fails to repair, it often causes the production process to stop. In severe cases, equipment damage or casualties occur. Faulty repairs are undesirable during the production process. Preventive maintenance is based on past operating experience, during the installation and use process, in the case of failure of the regulator valve, a preventive maintenance method on the regulator valve on time, its purpose is to prevent accidents, People usually formulate corresponding fault prevention measures according to the different operating conditions of the regulating valve, and maintenance can be performed because the fault does not occur, which can greatly reduce the probability of fault occurrence.
In practical applications of regulating valves, preventive maintenance and fault repair are usually combined and used. The former is supplemented by the latter to maximize the effective service life of the regulating valve. Only in this way can the utilization efficiency of the regulating valve be improved. Reducing the system failure rate has practical and positive significance for the improvement of production process efficiency and economic efficiency as well as reduction of energy consumption. It can effectively improve the quality of the system's regulation and ensure the long-term, safe and efficient operation of production equipment.
High Tenacity and High Modulus PE Fiber, called as UHMWPE fiber, is high-tech fiber in 1990s. Regarded as one of the worlds three high performance fibers (carbon fiber, aramid fiber and PE fiber).
UHMWPE fiber possesses such characteristics as high molecular weight, high degree of orientation and high crystallization. And its tenacity is 15 times over steel and 10 times over normal chemical fiber. Besides its also low density, high modulus, UV resistance, corrosion resistance, outstanding anti-impact and anti-incision. It's the highest tenacity and lowest density bulletproof material in the world.
UHMWPE fiber is widely used in national defense equipment such as tank, armored car, bulletproof plate, bulletproof helmet, bulletproof jacket, cut-resistance jacket, cut-resistant gloves and fabric; and also used in composites field such as composites materials for aviation and spaceflight, ropes for navy vessel, trawling net, ocean cage against winds and waves, sports equipment and construction projects.
Ballistic Material, Ballistic Nylon Fabric, Ballistic Protection Materials, Anti Ballistic Materials
NINGBO CHIHAN PROTECTION EQUIPMENT CO.,LTD. , http://www.bpvarmor.com