Industry new

Several methods for regulating the life of the valve

1. Large opening work extended life method
Let the regulator work as far as possible at the maximum opening, such as 90%. Thus, cavitation, erosion, and the like occur on the head of the spool. As the spool is broken, the flow rate increases, and the corresponding valve is closed again. This is continuously destroyed and gradually closed, so that the entire spool is fully utilized until the root of the spool and the sealing surface are broken and cannot be used. At the same time, the large opening degree of the throttle opening is large, and the erosion is weakened. This allows the valve to work at the intermediate opening degree and the small opening degree to increase the life of the valve by more than one to five times. If a chemical plant adopts this method, the service life of the valve is increased by 2 times.
2. Reduce S to increase the working opening and improve the life method
Decrease S, that is, increase the loss of the system except the regulating valve, so that the pressure drop distributed to the valve is reduced. In order to ensure the flow through the regulating valve, the opening of the regulating valve is inevitably increased, and at the same time, the pressure drop on the valve is reduced, so that Cavitation and erosion are also weakened. The specific methods include: the pressure drop of the orifice plate after the valve is throttled; the manual valve connected in series on the pipeline is closed, and the valve is obtained to obtain a better working opening. This method is very simple, convenient and effective when the valve selection is at a small opening.
3. Reduce the caliber to increase the working opening and improve the life method
By increasing the diameter of the valve to increase the working opening, the specific methods are: 1 change a small first-diameter valve, such as DN32 to DN25; 2 valve body does not change, replace the small valve seat diameter spool valve seat. If a chemical plant is overhauled, the throttle dgl0 is replaced with dg8, and the service life is doubled.
4. Transfer the damage location to improve life
Transfer the severely damaged area to a secondary location to protect the sealing and throttling surfaces of the valve seat.
5. Growth throttling channel to improve life method
The simplest way to increase the throttling channel is to thicken the seat to increase the seat bore and create a longer throttling channel. On the one hand, the sudden expansion after the flow-closing type of throttling can be postponed, and the position of the transfer is destroyed to make it away from the sealing surface; on the other hand, the throttling resistance is increased, the degree of recovery of the pressure is reduced, and the steam is reduced. The eclipse weakens. Some design the valve seat hole as a stepped, wave type, in order to increase the resistance and reduce the cavitation. This method is often used when introducing high pressure valves in the installation and retrofitting old valves, and is also very effective.
6. Change the flow direction to improve the life method
The flow-opening type flows toward the opening direction, and the cavitation and erosion mainly act on the sealing surface, so that the sealing surface of the valve core and the valve seat is quickly damaged; the flow-closing type flows toward the closed direction, cavitation and erosion. After throttling, below the seat sealing surface, the sealing surface and the root of the valve plug are protected, extending life. Therefore, when the valve for the flow-open type is used, when the problem of prolonging the life is more prominent, the life can be extended by one to two times by simply changing the flow direction.
7. Use special materials to improve life method
In order to resist cavitation (destruction of shapes such as honeycomb dots) and scouring (streamlined small grooves), special materials resistant to cavitation and erosion can be used to manufacture the throttle. This special material is 6YC-1, A4 steel, stellite, hard alloy and so on. For corrosion resistance, materials that are more resistant to corrosion and have certain mechanical and physical properties can be used. This material is divided into non-metallic materials (such as rubber, PTFE, ceramics, etc.) and metal materials (such as Monel, Hastelloy, etc.).
8. Change the valve structure to improve the life method
The purpose of improving the life is to change the valve structure or to select a valve with a longer life, such as a multi-stage valve, an anti-cavitation valve, a corrosion-resistant valve, and the like.
9. Cleaning method
The welding slag, rust, slag, etc. in the pipeline are blocked or jammed in the orifice, the guiding part and the balance hole of the lower bonnet, causing strain and scratches on the curved surface of the valve core, the guiding surface, and indentation on the sealing surface. Wait. This often happens in the early stages of the new commissioning system and after the overhaul. This is the most common failure. In this case, it must be unloaded for cleaning, remove the slag, if the sealing surface is damaged, it should be ground; at the same time, the bottom plug is opened to wash off the slag falling into the lower bonnet from the balance hole, and the pipeline Rinse. Before commissioning, let the regulating valve open completely, and the medium will flow into the normal operation after a period of time.
10. External scouring method
When some media that are easy to precipitate and contain solid particles are adjusted by ordinary valves, they are often blocked at the throttle and guide, and the gas and steam can be flushed at the bottom of the lower bonnet. When the valve is clogged or stuck, open the external gas or steam valve to complete the flushing operation without moving the regulating valve to make the valve operate normally.
11. Install the pipeline filter method
For small-diameter regulating valves, especially ultra-small flow regulating valves, the throttle gap is very small, and there should be no slag in the medium. In case of blockage, it is best to install a filter on the pipe in front of the valve to ensure the smooth passage of the media. With the regulating valve used by the positioner, the positioner does not work properly, and the blockage of the air passage throttle is the most common fault. Therefore, when working with the positioner, the air supply must be handled. The usual method is to install an air filter pressure reducing valve on the air supply line before the positioner.
12. Increase the throttling gap method
If the solid particles in the medium or the slag and rust that are washed away in the pipeline cannot be blocked or jammed due to the throttle opening, the throttle with a large throttle gap can be used instead. Valves and sleeves of windows and openings can be easily eliminated because their throttle areas are concentrated rather than circumferentially distributed. If it is a single or double seat valve, the plunger valve core can be changed to a "V" shaped valve core, or changed to a sleeve valve. For example, if a chemical plant has a double seat valve that is often stuck, it is recommended to use the sleeve valve and the problem will be solved immediately.
13. Media flushing method
Using the scouring energy of the medium itself, it washes and removes things that are easy to precipitate and easily clog, thereby improving the anti-blocking function of the valve. Common methods are: 1 changed to flow-type use; 2 uses a streamlined valve body; 3 puts the throttle port at the most violent point, and this method should pay attention to improve the erosion resistance of the throttle material.
14. Straight through to the angle method
The straight-through flow is inverted S, the flow path is complicated, and there are many dead zones in the upper and lower chambers, which provide a place for the precipitation of the medium. The angular connection, the medium is like flowing through the 90 °C elbow, the scouring performance is good, the dead zone is small, and it is easy to design into a streamline shape. Therefore, the use of a straight-through regulating valve can be changed to an angle valve when it is slightly blocked.

PREVIOUS：What is the definition of the definition of tNEXT：Adjustable pressure reducing valve series pre