The correct installation of the control valve is as important as the correct selection. The quality of the installation relates to the operating performance of the control system, control of quality, safety and cost, and so should be taken seriously. Control valve installed at the scene, the fire, explosion-proof, anti-leakage and put forward higher requirements, control valve noise pollution is also increasingly subject to the relevant departments. First, the control valve installation and construction requirements: Installation and construction of the general provisions of 1 ,. Control valve installation should follow the design drawings and design documents. 2, the installation of control valves should comply with the relevant national standards, for example, construction and installation quality inspection and evaluation standards, industrial automation instrumentation and acceptance of construction specifications, installation of electrical equipment construction and acceptance of norms. 3, the installation of control valves required equipment, auxiliary equipment and main materials should be consistent with existing national or ministerial standards of the relevant provisions. Second, the installation and construction precautions: Control valve installation precautions should be easy to operate, safety and standardization considerations. The details are as follows. (A) Control valve installation location and orientation: 1, in accordance with the provisions of the design drawings and design documents, the installation location should have sufficient space for installation, operation and maintenance; its location should be avoided in a vibration, humidity, It is susceptible to mechanical damage, strong electromagnetic interference, high temperature, severe temperature changes and corrosive gas. The installation should be firm and smooth. The installation position should be such that the control valve actuator is above the adjustment mechanism. Figure 6-8 shows the straight Travel control valve of the various installation orientation. Among them, the location is the preferred location, second choice location. 2, the control valve fluid flow control valve fluid flow direction should be consistent with the arrow marked on the valve body. Under special circumstances may not be subject to the provisions of the restrictions. 3, the control valve connected to the control valve threaded connection, flange connection and welding connections. Threaded connections for small-diameter control valves, installation of threaded control valve, you must also install a removable removable connector. Flanged flange connection and clamping connections are two kinds, connecting the nominal diameter of the flange should be consistent with the control valve take over diameter. Flanges also have different pressure levels, flange pressure level should be consistent with the control valve pressure level. The inner diameter of the flange should be equal to the inner diameter of the pipe. Flange and pipe axis perpendicularity allowable deviation of l °. Flange sealing surface should be flush. Flange and pipe coaxial tolerance t should meet: t ≤ 0.015D (1 / β) (6-27) Where, D is the pipe diameter; Xi is working conditions under the throttle diameter and the pipe diameter ratio . Flange connection should be force appropriate, to avoid excessive local pressure. Try to avoid the use of welded connections, welding connections must be installed at the same time removable removable connectors. When connecting the control valve, the inside of the connecting pipe should not be caused to have new bulges. For example, gaskets, weld seams, etc. should not protrude in the pipe. 4, the control valve and the upstream and downstream shut-off valve, bypass valve connection control valve, the downstream shut-off valve and bypass valve should be installed with the control valve. The length of the pipe between the upper and lower shut-off valves and the control valve should take into account the resistance of the pipe and the effect on the fluid flow. Long straight pipe length is conducive to the stability of the fluid after the shut-off valve, the fluid flow can be smooth, reducing the impact of turbulence and reduce noise; straight pipe length is short, the fluid has not stabilized after the shut-off valve into the control valve, the noise enhancement , But the short pipe length helps to reduce the pipeline resistance and increase the pressure drop at both ends of the control valve so as to reduce the distortion of the flow characteristics and is in favor of the stable operation of the control system. Therefore, it should be weighed and considered. Normally, there should be 10D ~ 20D straight pipe on the upstream side and 3D ~ 7D straight pipe on the downstream side. D is the pipe nominal diameter, if necessary, should be set rectifier device. (B), the choice of connection options. 1, the control valve and the upstream and downstream shut-off valve connection in a variety of ways, several commonly used connection options. In the picture, scheme A has a compact structure, small footprint, easy maintenance and operation, and the system is easy to empty or drain. But often can not meet the enough length of straight pipe, resulting in increased noise. Program B structure covers a larger area, the control valve position can be installed in the lower or upper part, easy to adapt to operational requirements, but the length of straight pipe is not easy to guarantee. The structure of scheme C is suitable for the angle control valve, can reduce the number of elbows, covers a smaller area. On the bottom into the side of the flow, there may be a longer upstream straight pipe length. The structure of program D is similar to that of program B and covers a large area. The structure of the solution E is suitable for the angle valve. Compared with the solution C, the length of the straight pipe section on the upstream side is shortened, which is not conducive to the stability of the fluid. The structure of Scheme F is the most common connection structure. It covers a large area, the pipeline resistance is small, but the operation and maintenance space is small. 2. Discharge valve, vent valve, drain valve connection, in order to facilitate the removal of the control valve should be carried out before the demolition of the valve before and after the pressure relief valve, the relief valve should be installed in the control valve and the upstream and downstream shut-off valve between. 3, vent valve, drain valve for the discharge of fluid entrained non-condensable gas and condensate. Installation, the controlled fluid, gas or steam, in order to facilitate the condensate discharge, the sewage valve should be installed in the lowest control valve group. Controlled fluid is a liquid, in order to facilitate the non-condensable gas vent, vent valve should be installed in the highest point of the control valve group. 4, Bypass valve. Control valve removal and maintenance, the bypass valve can be used to operate the production process. When charged with excessive traffic. With the control valve can not be properly adjusted, as a contingency measure, bypass valve can also be used as a control valve of the parallel connection program, the process control. To reduce costs, large-caliber control valve installed hand wheel actuator, can replace the bypass valve to operate. Bypass valve installation should be easy to operate, with the control valve, the downstream cut-off valve together to form a control valve group, therefore, should be installed with them, and at the same time to complete the construction and installation. The nominal diameter of the bypass valve is the same as the nominal diameter of the pipe, and the withstand voltage level is also consistent with the withstand voltage of the process. 5, the installation of the implementing agencies Usually, the implementing agencies and the control valve body directly connected, but the hydraulic actuator, long-stroke actuator and other implementing agencies and control valve body separately, the installation of implementing agencies should be noted that the implementing agencies with Rod and mechanical moving parts should be flexible, no loose or stuck and so on. Linkage length should be stable throughout the trip range, flexible and reliable. When connected to the control valve body with thermal displacement of the process piping, the relative position between the actuator and the valve body should be maintained. The handwheel actuator has side and top two, the installation should be left space for operation. Handwheel operation should be flexible, there is no stuck or reversed phenomenon. Should handwheel direction of rotation and valve opening relationship between the label. Limit devices should be adjusted to play a protective role. The hydraulic actuator should be lower than the controller installation, if it must be higher than the controller, the height difference should not exceed 1.0m, and should be installed in the pipeline gas exhaust valve, close to the controller installed check valve or Automatic shut-off valve. 6, the valve positioner installation Valve positioner valve position detection device and control valve stem or valve shaft directly connected, therefore, the installation should ensure that the feedback signal can be correct, timely reflect the valve position signal and changes. Normally, the valve positioner is supplied with the control valve, and both are connected by the manufacturer. When the production process control valve positioner needs to be added, it should ensure that the valve positioner valve position detection device action is correct, reliable and flexible. Feedback lever fulcrum mechanical gap should be as small as possible. Valve positioner signal lines should be properly connected, the gas source and output lines, input lines should be marked nameplate. Valve positioner valve position display signal should facilitate the operation and maintenance personnel to observe. 7, Other Accessories Installation Other accessories include valve position sensor, solenoid valve, limit switch, relay, electrical converter, the installation should comply with the relevant provisions of the product manual. Small flow control valve should be installed upstream filter. Serious turbulence, should be installed in the upstream rectifier device. 8, the installation of connecting pipe connection pipeline installation should pay attention to the following. 1), the signal trachea and gas line generally use PVC sheathed copper cable, diameter sL6Xl or g18Xl 2), the gas line should be close to the control valve. 3) Signal and hydraulic lines should be as short as possible to reduce signal skew and system time constants. 4) The pipeline should have sufficient scalability, and should not hinder the action of the implementing agencies. 5), welding slag should not fall into the pipe. The connecting pipe should be cleaned before installation to remove dirt, water and rust. Piping connecting pipelines should be neat and beautiful. 6), The hydraulic oil pipeline should be far away from the high temperature equipment and pipeline, and the distance from the hot surface should be more than 150mm. 7) Before installation, the drain valve and vent valve connected with the pipeline should be cleaned, removed, inspected and tested. 8), hydraulic and pneumatic piping system should be pressure test, and in line with the provisions. 9),. Connect the signal wire, the cable should be laid through the tube, the device side with a metal hose connection. Explosion-proof equipment should take the appropriate explosion-proof measures, all the protected system should be sealed. 10) The laying of pipelines shall not interfere with the operation of the operators and the maintenance of maintenance personnel. 11), connected pipelines should be marked nameplate. If necessary, the pipe can be fixedly connected by the support bracket to prevent the connection pipe from being unable to be fixed after the control valve is disassembled. 12), the connection line should avoid water and liquid immersion and corrosion or harmful gas intrusion. 9, additional pipe installation Additional pipe fittings have reduced diameter pipe and diameter pipe. The installation of additional pipe fittings to increase pressure loss and affect the control valve flow coefficient. Installation of additional pipe fittings, should be left in the connection space for easy maintenance, removal of the connecting bolts. Installation of pipe fittings should be installed support or stand, if necessary, add anti-vibration pads or anti-vibration spring. 10, the control valve and other accessories off the month purpose, insulation and heat required to degreasing the control valve and other accessories must be designed according to the provisions of degreasing. After degreasing the control valves, pipes and other natural ventilation or dry air or nitrogen blow dry, closed after inspection and preservation, should be kept clean and oil-free installation. Control valves and other accessories subject to adiabatic and heat tracing should be insulated and heat traced. Heating pipelines or electric heating with the laying of the installation should comply with the relevant provisions. Insulation with insulation materials and thickness should be consistent with the design requirements. Various support frames, supports and connecting lines to install control valves and accessories are to be painted. Paint the surface should be removed before the rust \ welding slag, burrs and dirt. The color and thickness of the paint, the conditions of the paint operation, etc. shall comply with the relevant provisions. 11, self-operated control valve to take the source components of the installation of self-pressure, differential pressure control valve pressure components with reference to the source of the parts installation requirements for construction. Self-temperature control valve to take the source components can refer to the temperature package installation requirements for construction. Third, the control valve on-site commissioning: After the installation of the control valve, the control valve on-site commissioning should be carried out in the production process before driving. Site commissioning sub-line debugging and system debugging. (A) line debugging Commissioning is used to check the signal line connected to the control valve, gas line or hydraulic line is connected properly. 1. Control valve input signal connection. Normally check with the positioner. The control valve input signal comes from the controller. Therefore, a start signal is output from the controller to check if the control valve is at the start position. An end signal is output to check if the control valve is at the end position. To do this, check the air supply pressure is normal; filter regulator work is normal; hydraulic system is provided hydraulic pressure is normal; power supply is normal; the output signal is correct, and in the measurement range at least 5 points to check Whether the input signal and the valve position satisfy the required relationship. Should check the gas, gas off the role of the right way, whether to meet the safety requirements of the production process. 2. Control valve output signal connection. Control valve output signal is the valve position signal, which can be analog signal or digital signal. Should check the control valve input signal at the same time, check the valve position signal is correct. When using HART or smart electrical valve positioners, check that the valve position information is correctly transmitted. Control valve throughout the trip should listen to the control valve spool and valve seat for mechanical vibration and abnormal noise. 3. Hand wheel mechanism debugging. Check the hand wheel mechanism can be properly rotated and action, limit and locking device is easy to use. 4. When the deviation exceeds the allowable deviation limit, the corresponding debugging should be carried out. For example, change the position of the position switch and check for leaks in the wiring or piping. (B), the system debug control valve is the final element of the control system, therefore, the control valve required for system debugging before running. System debugging should be carried out with the process operation. 1. Negative feedback debugging. The control system should meet the negative feedback requirements. Therefore, the controller, the detection transmission and the control valve (including the valve positioner) should be considered together with the controlled object, and the positive and negative effects of the controller should be set. The negative feedback criterion is that the total gain of open-loop control system is positive. After setting the controller positive and negative reaction mode, the analog input signal can be measured at the controller to increase or decrease, observing whether the output change of the controller meets the requirements of the mode of operation and checking whether the action direction of the control valve is correct or not It is possible to change the controlled variable in the decreasing direction. 2. Control valve pressure drop check. Control valve pressure drop check during water simulation debugging. During the entire stroke of the control valve, check whether the pressure drop at the two ends of the control valve changes, whether noise caused by cavitation or flashover occurs, whether the flow changes, whether it meets the designed flow characteristics, and the like. 3. Response time check. Some control systems on the control valve response time requirements, should check the control valve response time. The time required to start the timer when the controller output signal changes, until the valve position of the control valve reaches 63% of the final steady state position is the response time, which should meet the operating requirements of the process.