Control valve repair talk

Posted by uuuseff on November 19th, 2019

Control valve repair in general there are two: First, preventive maintenance, mainly refers to the regulator valve to ensure the reliable operation, and in the absence of failure to take precautionary measures, including the installation and use of regulating valve in the field A series of preventive measures; the second is the failure of maintenance, that is, in the case of failure of the control valve can not meet the operational requirements of a series of overhaul work, under normal circumstances in the production workshop is completed, under special circumstances may also be carried out directly on the pipeline service. Preventive maintenance Preventive maintenance is planned maintenance before the control valve fails, can be understood as routine maintenance, usually including the following work. 1.1 Elimination of stress lines due to combination or improper installation will produce a variety of stress, such as heat stress caused by high temperature medium, the installation of the fastening force is not balanced due to stress, some man-made collision to the control valve and its pipeline caused by stress. The stress on the regulating valve and its pipeline, it is easy to affect the performance of the regulating valve, will seriously affect the regulation system itself, resulting in deformation of the stem and the guide and the valve seat can not be aligned; for the split valve The body of the control valve, valve body flange may cause disengagement; stress may also cause seat leakage and so on. Therefore, at all times ensure that stress is avoided or relieved, directing the stress away from the regulating valve. 1.2 Check the support situation The best position to install the control valve is the valve stem stroke direction and the actuator above the body in a vertical plane. If the control valve must be installed in a position where the valve stem moves horizontally or the valve stem moves in a certain inclination to the horizontal plane, the actuator should be supported so that the various parts of the control valve are in a natural state. If you do not add support or improper support improper installation may cause valve stem and valve seat of the different heart, easily lead to poor change or filler leakage and other failures. Even if the control valve has a fixed and support measures, but also must be regularly checked, usually 2 to 3 months to check. 1.3 to clear or prevent foreign matter to enter Check the valve regularly to connect the pipeline without rust, welding slag, dirt, etc., should be promptly removed after the discovery. If the control valve and piping easy to accumulate foreign matter, it is necessary to consider the upstream side of the control valve to install a simple filter device. In the process medium easy to infiltrate hard debris occasions, be sure to install a permanent filter device. Because the valve is closed, a small piece of rust or welding slag is sufficient to destroy the well-worn seat sealing surface, Moreover, these dirt will also cause valve spool and seat wear, affecting its normal operation. 1.4 Regularly check the gas source and power gas source is one of the key energy sources driving the control valve. Pneumatic valve diaphragm chamber does not consume air, but if the gas source system contains moisture, oil and other impurities, it will plug the valve positioner, the relay and other clogging and failure. Therefore, we must regularly check the gas source and power supply to ensure that the gas source clean, dry, reliable power supply. 1.5 Regular Maintenance and Refueling Fillers and lubricators need to be readjusted after a short period of use. Dusty occasions to around the stem with a plastic sleeve or rubber sleeve to protect the stuffing box and the guide parts, corrosive gases or droplets in the presence of special protection measures should be used, the general use of anti-corrosion bag wrapped around the control valve, but to Attention can not affect its operation. In the fire resistance requirements of the occasion, you can use special refractory coatings, sets of fire bags and other methods, fire bag material containing multi-layer ceramic fiber or glass fiber. 1.6 Transport and storage control valve Assemble and paint and install the actuators, handwheels, locators and other accessories as required, in order to prevent foreign substances into the control valve, connecting all the air control valve interface must be plugged, connect the flange Install the protective cover, pay attention to the various connection parts, such as the valve positioner intake pipe, the actuator interface state. Any protruding attachments that are easily damaged, such as pressure gauges for oiler and potentiometer, should be removed from the fitting, packaged separately from the regulator, and shipped together. Control valve dedicated bracket fixed to prevent loosening, to ensure the overall vertical position or horizontal position. If the long-distance transport, it is best to use a solid wooden shipping. When storing the control valve, do not support the control valve in sensitive areas such as valve positioners, stems and the like. Environmental conditions for transport and storage shall meet the requirements of the product specification. Storage area is best not to carry out other operations, can not be avoided, we must be careful not to touch the control valve. Locations should also be protected from harsh conditions such as wind, dust, rain and the like. In the absence of a suitable site, the regulator must be installed in a damp-proof bag prior to storage or in a similar container. 1.7 Inspection of Safe Operation Regulating valves and related accessories used in potentially explosive atmospheres should be checked for their safe operation, such as tightening of sealing cap, operation of barrier, power supply, etc. to ensure safety of control valves and related accessories run. 2 faulty maintenance control valve can not operate or can not meet the operational requirements, it means there is a fault, you must repair the fault. In the case of failure can not be affirmed, the general can follow the steps below. 2.1 Cleaning After the faulty regulating valve is removed from the pipeline, the first step of maintenance is to thoroughly clean the regulating valve. The control valve is easily polluted by the process fluid. If the process medium is corrosive, explosive or radioactive, it will cause harm to the human body. The components soaked in the process medium must be cleaned by a special method. Cleaning methods vary with the nature of the process medium. Under normal circumstances, as long as the water or steam can be purged, for some pollution, such as alkaline media to be used pickling method, the pollution of heavy metals will be at high temperatures, for a long time under special treatment. When cleaning to avoid repeated contamination, to be carried out in a safe place. All cleaning tools such as containers, heating equipment, steam hoses, washing equipment and so on should be prepared in advance. 2.2 Removal of the control valve Removal of the control valve to be marked with the body corresponding to the connection position of the actuator, the actuator and the bonnet separated from the bonnet and the valve body apart, the bonnet and stuffing box after the demolition of parts, From the valve body can be removed spool, stem and other components. All disassembled parts and components must be carefully inspected to determine the parts to be repaired and replaced. Usually after the valve is disassembled, pay attention to the following parts when checking: 1) The inner wall of the valve body. Check the pressure, corrosion resistance; 2) seat. Due to the medium infiltration, the threaded surface of the fixed valve seat is easily corroded and the valve seat is loosened. For high pressure occasions, the corrosion or damage of the valve seat sealing surface should also be inspected. Of course, in some structures, the valve seat and the valve body are not The use of threaded connections, but the way with a gasket compression, but no matter which way the valve seat and valve body sealing parts must focus on inspection; 3) spool. To carefully check the various parts of the valve core is corroded or worn, especially in the case of high pressure differential valve wear more serious, the other stem also check whether there is a similar situation, and whether the connection with the spool loose, etc .; 4) Sealed packing and gasket. Check the seal packing and gasket aging, cracking and so on, with the surface is intact. 2.3 Disassembly The actuator should be carefully inspected after the actuator is removed. Brackets, diaphragms, springs, push rods and threaded connections, etc., where the bracket is a force member and can not be cracked; the diaphragm is a critical component and can not be damaged or aged; the spring Without cracks, for multiple spring actuators, the performance of the entire actuator can be severely affected as long as one of the springs is damaged. No matter what kind of parts, once corroded or corroded, it is best to replace the new parts. 2.4 Reassembly After all parts and components have been repaired, reassemble. In the process of reassembly, pay attention to select the appropriate gasket and bolt connections, accurate alignment, uniform tightening, to prevent flange leakage. The torsional load on a bolt or stud depends on its size and must not be over-tightened. Packing type, quantity and installation methods have a direct impact on the sealing performance, assembly can not be taken lightly. After reassembly of the actuator, but also to the friction parts of the appropriate lubricant, these parts include stem and guide, actuator push rod and guide, bearings, transmission parts, adjusting nut and so on. 2.5 Test After reassembly, the control valve must be tested

Sugar-Specific Carbon

Sugar-Specific Carbon,Activated Carbon,Carbon Activated

Wood Based Activated Carbon,Coal Based Activated Carbon Co., Ltd. , http://www.nsactivatedcarbon.com