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Pneumatic control valve in the production process of debugging introduced
First, the application of the control valve in the modern factory Control valve supporting the use of other instruments can be achieved in the production process flow, level, pressure, temperature and other process parameters such as liquid, gas, steam and other automatic adjustment and remote control functions . ... First, the application of regulating valve in modern factories Control valve supporting the use of other instruments can be achieved in the production process flow, level, pressure, temperature and other process parameters and other media such as liquid, gas, steam and other automatic adjustment and Remote control function. Pneumatic membrane valve which is the ultimate implementation of automatic regulation system, the control valve in the modern factory application Pneumatic control valve and other instruments supporting the use of the production process can be achieved flow, level, pressure, temperature and other process parameters such as media Liquid, gas, steam and other automatic adjustment and remote control functions. Among them, the pneumatic film regulating valve plays a very important role as the final actuator of the automatic adjusting system. The application of the regulating valve is directly related to the quality and safety of production. Second, the common fault valve, the reasons for analysis and solutions (1) control valve does not move. Reason: There is no signal pressure or diaphragm rupture, the diaphragm leaks, diaphragm thrust decreases; spool and seat or bushing stuck, stem bending and other reasons that the valve can not move. Solution: The signal line, the gas source connector to connect or replace the diaphragm; Straighten the stem or replace the stem. (2) regulating valve action is normal, but can not afford to regulate the role. Reason: spool off or blocked. Solution: the spool off the spool and stem firmly connected to the piping problems of the competent authorities to clear the pipeline. (3) regulating valve slow or beating. Reason: the aging or dry packing seal to increase the friction between the stem and packing; viscous body contains large dirt and clogging, coking and so on; diaphragm and "O" -shaped ring and other leaks also. Solution: replace the seal packing, readjustment; remove dirt, coking, etc .; fasten the membrane head, or replace the diaphragm, O-ring. (4) regulator valve instability or oscillation. Reason: the choice of regulating valve diameter is too large; single-seat valve medium flow in the valve direction and closing the same direction. Spool and guide sleeve severely worn. Solution: Replace the valve with the proper valve diameter; adjust the valve direction; improve the bonding surface (grinding) or replace the valve core and the guide sleeve. Third, the typical fault control valve repair program to "regulate the valve action is normal, but can not afford to regulate the role of" fault as an example to describe the maintenance program: a chemical plant vinyl chloride plant, the use of valves for Sichuan Instrument Factory 11 single-seat control valve. This production line with an annual output of 100,000 tons of plastic particles, vinyl chloride plant compression, conversion, distillation section has two production lines. In addition to compression, the conversion and fractionation section are extensive use of the control valve, the working environment of each control valve is completely different, and each pipe usually have only one control valve, some control valve bypass also can bypass Manual valve control. If the control valve fails, you can open the bypass valve to ensure normal production. Therefore, before the demolition, we must carefully analyze the cause of the failure of the control valve, develop a sound maintenance program. 1. Maintenance methods and standards. Maintenance methods: (1) according to the rules of operation to hand over to require replacement of qualified maintenance workers carrying canisters, vinyl chloride odor sensitive instrument, and gas station staff custody before demolition of the valve. (2) Turn off the air supply, remove the positioner and the air source tube, disassemble the valve (.3) and connect the valve stem, check the connecting condition of the valve stem, check whether the connecting pin can be removed, can not Remove the use of special tools to take, or change the hole. 2. After the valve repair assembly. (1) The valve should be assembled before the cleaning of all components to check the assembly sequence should be bottom-up, the gasket should be coated with grease, adding filler to enrich uniform. (2) All fastening bolts and packing should be coated with grease before assembly, which will benefit the next maintenance and lubrication. 3. Valve calibration. After the valve assembly is installed on the locator, gas source to adjust. The calibration point should not be less than 5 points, 0%, 25%, 50%, 75%, 100%. Slowly turn each point signal into the positioner, and observe whether the stroke pointer corresponds to the ruler scale. Otherwise, repeat the adjustment until it reaches the standard. 4 test and acceptance. (1) After the valve calibration standard installed on the pipeline, no problem to confirm the process to inform the workshop, to hand over the formalities. (2) With the process staff from the scene to the total control operation. (3) check after repair records file information is complete and accurate. (4) When the valve is introduced into the medium, check whether the packing and the flanges on both sides leak. (5) 72 hours after the normal operation of the control valve, qualified by the relevant technical director. 5. Safety Precautions. (1) Maintenance Safety Precautions: maintenance must be more than two jobs; into the field maintenance must wear the provisions of the protection supplies; electric valve abnormalities need to be addressed, must obtain the approval of process personnel, to take safety measures before operation. (2) Safety Precautions for Inspection and Repair: The valves used online must be handed over for inspection and repair; the process medium must be drained clean before the on-line valve is disassembled and the operation can not be leaked; the gas source should be turned off during maintenance; , You must use special tools, do not damage the parts; removed parts and exposed valve body covered with soft material. (3) Put into operation Safety precautions: Before commissioning, the technicians should be informed to go through the formalities for delivery; when commissioning, the technicians and maintenance staffs should cooperate closely with each other. Four, the control valve removal process (1) cut off the power supply, gas source; remove the power cord and signal lines and then remove the trachea; (2) connecting the trachea (through the valve, the setter to the membrane head), set the valve Of the pressure on the nameplate spring minimum working pressure value; (3) Then remove the split nut, remove and close the gas source and remove; (4) the pointer block and the lock nut loose; , Remove the bracket; (6) Diagonal release and remove the bonnet nut, followed by removal of the bonnet, the spool, the guide sleeve, toothed shims; removal is complete, check the cause of the malfunction, the spool and stem reconnect. Then assemble the valve body in the reverse order of disassembly.