1. Wide open working life extension method

Allow the regulator to work at maximum opening as soon as possible, such as 90%. Thus, cavitation, erosion and other damage occurs at the head of the spool. With the spool failure, the flow increases, the corresponding valve to close a little, so that the continuous damage, gradually closed, so that the entire spool is fully utilized, until the spool root and sealing surface damage, can not be used. At the same time, the large opening of the throttle clearance, erosion weakened, this than the beginning of the valve in the middle opening and small opening on the working life of 1 ~ 5 times. If a chemical plant using this method, the service life of the valve increased by 2 times.

2. Reduce S and increase working openness to improve life

Reduce S, that is, increase the loss of the system in addition to the control valve, so that the pressure drop distributed to the valve to reduce, in order to ensure that the flow through the control valve, will inevitably increase the opening of the control valve, at the same time, the pressure drop on the valve, cavitation, erosion is also weakened. Specific measures are: after the valve orifice throttle consumption pressure drop; Close the manual valve in series on the pipeline until the regulator gets a better working opening. It is very simple, convenient and effective to use this method when the valve is in small opening at the beginning.

3. The method of reducing caliber, increasing working opening and improving service life

By reducing the diameter of the valve to increase the working opening, the specific method is: (1) change a small gear diameter valve, such as DN32 to DN25; Body does not change, replace the small seat diameter of the spool seat. For example, dgl0 of throttling parts is replaced with dg8 during overhaul of a chemical plant, thus doubling the service life.

4. Transfer the failure position to improve service life. Transfer the serious damage to a secondary position to protect the sealing surface and throttling surface of the spool seat.

5. Increase throttling channel and increase life span method

The simplest way to increase the throttling channel is to thicken the seat so that the seat hole grows to form a longer throttling channel. On the one hand, it can make the sudden expansion and delay after flow closed throttling, which can transfer the failure position and make it far away from the sealing surface. On the other hand, it increases the throttle resistance, reduces the pressure recovery degree and weakens the cavitation. Some of the valve seat hole designed as a step, wave, is to increase resistance, reduce cavitation. This method is often used in the introduction of high pressure valves and to improve the old valve is also very effective.

6. Change the flow direction to improve the life span method

Flow open flow towards the open direction, cavitation, erosion mainly in the sealing surface, so that the valve core root and valve core valve seat sealing surface quickly suffered damage; Flow towards the closed direction flow, cavitation, erosion in the throttling, seat sealing surface below, to protect the sealing surface and the root of the spool, extended life. When the problem of prolonging the life of the valve is serious, it can prolong the life 1 ~ 2 times only by changing the flow direction.

7. Use of special materials to improve life

For cavitation-resistant (failure shape such as honeycomb small points) and erosion (streamline small groove), can be converted to cavitation-resistant and erosion of special materials to manufacture throttle. This special material is 6yc-1, A4 steel, stale, hard alloy, etc. In order to resist corrosion, materials with certain mechanical and physical properties can be used instead. This material is divided into non-metallic materials (such as rubber, teflon, ceramics, etc.) and metallic materials (such as monel, harrods, etc.).

8. Change valve structure to improve service life method

Change the valve structure or choose a longer life of the valve to achieve the purpose of improving life, such as the choice of multi-stage valve, anti-cavitation valve, corrosion valve.

9. The cleaning method

The welding slag, rust and residue in the pipeline cause blockage or stuck in the orifice, guiding position and balance hole of the lower cover, causing the surface of the spool, guiding surface to be pulled and scratched and the sealing surface to be indentation. This often occurs in the early stages of new commissioning systems and after major repairs. This is the most common failure. In this case, must be removed for cleaning, remove slag, such as sealing surface damage should also be grinding; At the same time, open the bottom plug to flush out the slag falling into the lower cover from the balance hole and flush the pipeline. Before putting into operation, let the regulating valve fully open and the medium flow for a period of time before being put into normal operation.

10. External scour method

For some easy to precipitate, contain solid particles of the medium using ordinary valve regulation, often in the orifice, guide to plug, can be under the cover of the plug at the bottom of the external erosion of gas and steam. When the valve is blocked or stuck, open the external gas or steam valve, you can complete the washing work without moving the regulator, make the valve normal operation.

Install pipe strainer method

For small diameter control valve, especially the ultra small flow control valve, its throttle clearance is very small, there can not be a little slag in the medium. In case of blockage, it is best to install a filter in the pipeline in front of the valve to ensure the smooth passage of media. For regulator valves with positioner, the positioner does not work properly, and the choke blockage is the most common fault. Therefore, when working with the positioner, must deal with the air source, the usual method is to install the air filter pressure reducing valve in the air source pipeline before the positioner.

12. Increase the throttle clearance method

Solid particles such as the medium or washed off in pipe welding slag and rust due to pass the throttle mouth such as congestion, jam, such as fault, can convert the throttle gap bigger throttle piece - throttling area of a window, open the valve core and the sleeve, rather than the circumference of a circle because of the throttling area of concentration distribution, fault can easily be ruled out. If it is a single, two - seat valve can be changed to the plunger - shaped spool "V" - shaped valve, or to sleeve valve, etc. For example, a chemical plant has a two-seat valve often stuck, recommended to switch to sleeve valve, the problem immediately solved.

13. Medium scour method

Using the medium itself scour energy, scour and take away easy precipitation, easy to plug things, so as to improve the anti-blocking function of the valve. Common methods are: (1) change to flow closed type use; (2) use streamlined valve body; (3) the orifice will be placed in the most severe erosion, the use of this method to pay attention to improve the erosion resistance of the throttle material.

14. Change the straight path to the corner method

The pass-through flow is inverted S flow with complex flow path and multiple dead zones of upper and lower chamber, providing a place for medium precipitation. Angle connection, flows through 90 ℃ medium like elbow, washing performance is good, dead zone is small, easy, designed to streamline. Therefore, the use of straight regulating valve can be changed to Angle valve use when there is a slight blockage.

15. Grinding method

Fine grinding, eliminate traces, reduce or eliminate the sealing gap, improve the surface finish, in order to improve the sealing performance.

      Cooper