Maintenance methods commonly used in the use of Control Valve

Maintenance methods commonly used in the use of control valves:

The regulating valve is divided into electric regulating valve and pneumatic regulating valve, and there are also hydraulic regulating valves on a few occasions. There are generally two kinds of control valve maintenance:

1. Preventive maintenance, mainly refers to the preventive maintenance measures taken in the absence of failure in order to ensure the reliable operation of the regulating valve, including a series of preventive measures taken when the regulating valve is installed and used on the spot.

2. It is fault maintenance, that is, a series of maintenance work carried out when the regulating valve can not meet the operation requirements under the condition of failure, generally completed in the production workshop, and may also be repaired directly on the pipeline under special circumstances.

1. Preventive maintenance: The preventive maintenance is a planned maintenance before the control valve has failed. It can be understood as routine maintenance, usually including the following tasks.

1.1 eliminate stress; pipeline will produce various forces due to improper combination or installation, such as thermal stress caused by high temperature medium, stress caused by uneven fastening force during loading, stress caused by artificial impact on regulating valve and its pipeline, etc. These stresses can easily affect the performance of the regulating valve on the regulating valve and its pipeline, which will seriously affect the regulating valve system itself, resulting in the deformation of the valve stem and guide parts and unable to align with the center of the valve seat; for the regulating valve of the split valve body, it may cause the valve body flange to be detached; the stress may also cause the valve seat leakage, therefore, the stress should be avoided or eliminated at all times. Force guides away from the control valve.

1.2 Check the support condition; the optimal position of the installation regulating valve is that the stroke direction of the valve stem is in a vertical plane with the actuator above the valve body. If the regulator valve must be installed at a position where the valve stem is moved horizontally or the direction of movement of the valve stem is inclined with respect to the horizontal plane, the actuator should be supported so that the various components of the regulating valve are in a natural state. If the adjustment valve stem and the valve seat are not provided with the support or the support is not properly erected, the valve stem and the valve seat can be caused to be different, so that the fault can be easily caused or the packing leakage and the like, even if the regulating valve has fixed and supporting measures, the check must be carried out on a regular basis, usually for 2 to 3 months. Once. 

1.3 to remove or annoy foreign bodies, check regularly for rust, welding slag, dirt and so on in the connection pipe of the regulating valve, and remove them in time after discovery. If it is easy to accumulate foreign bodies in the regulating valve and pipe, it is necessary to consider installing a simple filter device on the swimming side of the regulating valve. In the case of easy infiltration of hard sundries into the process medium, a permanent filtration device must be installed. Because when the regulating valve is closed, a small piece of rust or welding slag is enough to destroy the well-ground sealing surface, and these dirt also cause wear and tear on the regulating valve core and seat, affecting its normal operation.

1.4 check the gas source and power supply on a regular basis; the gas source is one of the key sources of energy to drive the regulating valve. Although the membrane chamber driving the regulating valve does not consume air, if the gas source system contains moisture, oil pollution and other impurities, it will block the valve locator, relay and other accessories and fail. Therefore, it is necessary to check the gas source and power supply regularly to ensure that the gas source is clean, dry and reliable.

1.5 regular maintenance and refueling; packing and oil injection need to be readjusted after short-term use. In dusty situations, plastic sleeve or rubber sleeve should be used to protect packing letter and guide position around valve stem, and special protective measures should be adopted when corrosive gas or droplets exist. Generally, anticorrosive bags should be used to wrap the regulating valve, but attention should not be paid to its operation. In the case of refractory requirements, special refractory coating, fire bag and other methods can be used, the material of fire bag contains multi-layer ceramic fiber or glass fiber.

1.6 Transportation and custody; after assembling and painting and installing actuator, handwheel, locator and other accessories as required, in order to prevent foreign substances from entering the regulating valve, all air interfaces connected to the regulating valve should be blocked, the connecting flange should be fitted with a protective cover, and attention should be paid to various connecting parts, such as the valve positioner intake pipe and the state of the executive interface. Any prominent accessories such as oil injectors and potentiometers that are vulnerable to damage should be removed from the joint, packaged separately from the control valve and transported together. The regulating valve shall be fixed with a special bracket to prevent loosening, in a vertical or horizontal position as a whole. If it is transported remotely, it is best to use it Solid wooden cases for shipment. Do not support the regulating valve in sensitive areas, such as valve locator, stem, etc., when keeping the regulating valve. The environmental conditions of transportation and custody shall meet the requirements of the product specification. It is best not to carry out other operations in the custody area. When it is inevitable, care must be taken not to touch the regulating valve. The place should also avoid being affected by bad conditions such as sand, dust, Rain Water and so on. If there is no suitable place, the regulating valve must be placed in a moisture-proof bag or in a container before storage.

1.7 Inspection of safe operation; control valves and related accessories used in explosive and dangerous places shall be checked for their safe operation, such as whether the seal cover is tightened, the operation of the safety grid, the supply of power supply, etc., to ensure the safe operation of the regulating valve and related accessories.

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