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Regulating valve before installation and put into operation to pay attention to what issues?
Regulating valve should pay attention to problems before installation and put into operation: Regulating valve is a very common and particularly important control equipment in industrial production, it is normal or not directly related to the normal operation of the entire plant production. At present, with the rapid development of control valve technology, the manufacturer and form of control valve are very numerous and have different functions. The following focuses on the common problems that various types of control valves should pay attention before installation and operation. First, the control valve installed before the purchase inspection Control valve purchase inspection is a very important part to confirm the arrival of the control valve to meet the design requirements. Regulating valve for each technical requirements should meet the design requirements, but the purchase inspection should focus on checking the following content. 1, body / valve trim specifications This content mainly includes: valve model, valve type, nominal diameter, seat size, spool form, flow characteristics, leakage level, valve body material, valve material, seat material , CV value, flange standard grade size and sealing surface form, etc., as long as they found that one of the same content and design should be subject to the design identified and recognized. 2, the implementing agency part of the main check this should be the executing agency type, type, form of action, spring range, supply pressure. 3, the locator part of the main check locator input signal, air pressure, electrical and gas source interface size and explosion-proof rating, of which explosion-proof rating may not be less than the design level requirements. 4, Accessories According to the technical requirements of the control valve design carefully clean the annex, such as filter valve, valve position switch, solenoid valve, hand wheel mechanism, special tools. The above contents of the inspection can be cleaned, measuring instruments, check the nameplate and special testing methods (such as flange and bolt material can be identified by spectroscopy) and other methods to achieve. Second, the control valve hydraulic test valve body pressure test includes the valve body pressure test and the valve when the valve leak test. Typically, when the design pressure exceeds 10MPa control valve, the valve body must be pressure test to check the pressure on the valve body itself and the valve cover. 1, the valve pressure test should pay attention to the problem (1) regulating valve body pressure test Manual pressure test pump hydraulic test, the use of electric pressure test pump is strictly prohibited. (2) test medium is clean water. (3) The test pressure is 1.25 times of the design pressure. (4) pressure test pressure gauge should be verified, the accuracy should not be less than 1.5, the upper limit of the scale should be 1.5 to 2 times the test pressure. (5) Air-Opened Valve When the pressure-proof test of the valve is carried out, the valve plug opens at least 20% of the opening degree. It must be kept in mind that the valve plug is prevented from being over-pressurized and damaged. Under normal circumstances, the control valve spool is allowed to a certain amount of leakage, according to the difference between the control valve leakage level, generally only requires the high differential pressure control valve (V, VI leakage) leak test. 2, the leakage test should pay attention to the problem (1) regulating valve body pressure test using a manual pressure test pump hydraulic test, the use of electric pressure test pump is strictly prohibited (Class VI leak valve pressure test). (2) The test medium is clean water (class VI leaking valves use clean air). (3) Leakage rating The test pressure is the maximum differential pressure designed for the valve operation (see design parameters). (4) pressure test pressure gauge should be verified, the accuracy should not be less than 1.5, the upper limit of the scale test pressure of 1.5 to 2 times. Third, the adjustment of the regulator valve Newly installed pneumatic regulator should be installed before the monomer adjustment. Adjustment should reach the performance indicators: Basic error: ± 1.5% Return error: 1.5% Insensitive area: 0.6% Now, the valve valve and the electrical valve positioner manufacturers are many, different functions, the electrical valve positioner trend In the intelligent, specific adjustment methods are different, not repeat them here. Fourth, the installation of regulating valve Regulating valve installation is the key issues that should be noted that the quality of the installation is directly related to the commissioning valve and performance. The following problems should be observed during the installation: (1) The valve must be carefully cleaned of dust accumulated during storage before installation, and should be kept clean during installation. Damage to the valve seat and trim due to dirt and dust. To protect the cleaning, it is usually possible to attach flaps to the ends of open flanges that are not welded on the same day. (2) When the control valve is installed, the arrow on the valve should be consistent with the flow direction of the medium. (3) Control valves are precision components that, if they are stressed by pipe deformation, will disrupt normal operation. Therefore, flange and pipe installation should be vertical and accurate position to avoid pipe deformation. Well, the pipe should be properly supported to prevent it from buckling under the weight of the valve. (4) The control valve must be especially careful when welding with the pipe. If the control valve and pipe welding attention is not enough, failed to eliminate the stress, it will have deformation. Welding, welding slag must be strictly avoided splashing into the valve, the presence of welding slag detrimental to the performance of the valve, if the splash splashed directly on the spool, ranging from a direct impact on the control valve action, heavy damage spool and seat. (5) When the pipe is under pressure test and blow-off, the control valve should be removed and connected with the corresponding straight pipe section to prevent the debris such as welding slag and iron cutting from getting stuck between the valve core and the valve seat. Remove the valve opening flange end of the plastic wrap tightly. Fifth, the control valve linkage test control valve installed in the device must be linked before the test drive. Linkage test should focus on the following points: (1) control valve linkage test before the process pipeline must be rigorously purged and qualified to purge unqualified pipeline is strictly prohibited to install the control valve, because the pipeline residues such as welding slag, dust Other hard debris will damage the valve seat and seat sealing surface. (2) butterfly valve should be checked before the linkage valve should not be pressure-tested or blocked blind. (3) Control valve with handwheel mechanism, handwheel mechanism should be in "release" position. Check the air supply valve pressure regulator valve to meet the gas requirements. Sixth, in the process of installation of industrial automation instruments, regulating valve installation and commissioning of the most complex, most difficult and most prone to problems. Throughout the process, instrumentation and pipe professional should be coordinated with each other, with each other, work closely with the problems promptly resolved in a timely manner, in strict accordance with the requirements, according to the rules of operation, the only way to successfully ensure the quality of the installation and commissioning valve quality control In order to ensure the smooth progress of the entire installation project and the smooth operation of the entire industrial plant.