Preventive maintenance solutions for pressure regulating valves, electric regulating valves, pneumatic regulating valves, self operated regulating valves, etc!

Preventive maintenance solutions for electric control valves, pneumatic control valves, self operated control valves, etc!

There are generally two types of maintenance for pressure regulating valves: one is preventive maintenance, which mainly refers to the preventive maintenance measures taken to ensure the reliable operation of the regulating valve before any faults occur, including a series of preventive measures taken during the installation and use of the regulating valve on site; The second is fault repair, which refers to a series of maintenance work carried out when the pressure regulating valve cannot meet the operational requirements in case of a fault. Generally, it is completed in the production workshop, but in special circumstances, it may also be directly repaired on the pipeline.

Preventive maintenance

Preventive maintenance is a planned overhaul before the failure of the regulating valve, which can be understood as routine maintenance and usually includes the following tasks.

1. Relieve stress

Due to improper combination or installation, pipelines can generate various stresses, such as thermal stress caused by high-temperature media, stress caused by uneven tightening force during installation, and stress caused by certain collisions on regulating valves and their pipelines. These stresses act on the regulating valve and its pipelines, which can easily affect the performance of the regulating valve. In severe cases, they can affect the regulating system itself, causing deformation of the valve stem and guide components and inability to align with the valve seat center; For regulating valves with split valve bodies, it may cause the valve body flange to detach; Stress may also cause valve seat leakage, etc. Therefore, at all times, it is important to avoid or eliminate stress and direct it away from the regulating valve.

2. Check the support condition

The optimal position for installing a regulating valve is to align the stroke direction of the valve stem with the actuator above the valve body in a vertical plane. If the regulating valve must be installed in a position that allows the valve stem to move horizontally, or when the direction of movement of the valve stem has a certain inclination angle with the horizontal plane, the actuator should be supported so that all components of the regulating valve are in a natural state. If no support is added or the support is not properly added, it may cause the valve stem and seat of the regulating valve to be misaligned, which can easily lead to differential deformation or leakage of the packing. Even if the regulating valve has fixed and supporting measures, it must be inspected regularly, usually every 2-3 months.

3. Inspection of safe operation

The safety operation of regulating valves and related accessories used in explosive hazardous areas should be checked, such as whether the sealing cover is tightened, the operation of safety barriers, power supply, etc., to ensure that the regulating valves and related accessories can operate safely.

4. Remove or prevent foreign objects from entering

Regularly check whether there is rust, welding slag, dirt, etc. in the connecting pipeline of the regulating valve, and promptly remove them if found. If foreign objects are prone to accumulate in the regulating valve and pipeline, it is necessary to consider installing a simple filtering device on the upstream side of the regulating valve. In situations where hard debris is easily infiltrated into the process medium, a permanent filtering device must be installed. Because when the regulating valve is closed, a small piece of rust or welding slag is enough to damage the well ground sealing surface of the valve seat, and these pollutants can also cause wear on the regulating valve core and seat, affecting its normal operation.

5. Regular maintenance and refueling

The packing and oiler need to be readjusted after short-term use. In dusty environments, plastic or rubber sleeves should be used to protect the packing box and guide parts around the valve stem. In situations where corrosive gases or droplets are present, special protective measures should be taken. Generally, anti-corrosion bags should be used to wrap the regulating valve, but care should be taken not to affect its operation. In situations where fire resistance is required, special fire-resistant coatings, fireproof bags, and other methods can be used. The material of the fireproof bag contains multiple layers of ceramic fibers or glass fibers.

6 Transportation and storage

After assembling and painting the regulating valve, and installing accessories such as the actuator, handwheel, and positioner as required, in order to prevent foreign substances from entering the regulating valve, all air interfaces connected to the regulating valve should be blocked, and protective covers should be installed on the connecting flanges. Attention should be paid to the status of various connecting parts, such as the intake pipe of the valve positioner and the actuator interface. Any protruding accessories that are easily damaged, such as pressure gauges for oil injectors and potentiometers, should be removed from the connector, packaged separately from the regulating valve, and transported together. The regulating valve should be fixed with a dedicated bracket to prevent loosening and ensure the overall vertical or horizontal position. If transported over long distances, it is best to use sturdy wooden crates for shipping.

When storing regulating valves, do not support them in sensitive areas such as valve positioners, valve stems, etc. The environmental conditions for transportation and storage should meet the requirements of the product manual. It is best not to carry out other operations in the storage area. When unavoidable, it is necessary to be careful not to touch the regulating valve. The place should also avoid being affected by harsh conditions such as sandstorms, dust, and rain. If there is no suitable place, the regulating valve must be packed in a moisture-proof bag or placed in a similar container before storage.

7. Regularly check the gas source and power supply

Gas source is one of the key energy sources for driving pressure regulating valves. Although the membrane chamber of the pneumatic control valve does not consume air, if the air source system contains impurities such as moisture and oil, it can cause blockages and malfunctions in accessories such as valve positioners and relays. Therefore, it is necessary to regularly inspect the gas source and power supply to ensure that the gas source is clean, dry, and the power supply is reliable.