Methods of improving the service life of control valve

Methods of improving the service life of regulating valve

Extended service life method with large opening

Let the regulating valve work at the maximum opening from the beginning, such as 90%. In this way, cavitation, erosion and other damage occur on the valve core head.

As the valve core is damaged and the flow increases, the corresponding valve shall be closed a little more, so as to continuously damage and gradually close, so as to make full use of the whole valve core until the valve core root and sealing surface are damaged and can not be used.At the same time, the large opening working throttle clearance is large and the erosion is weakened, which increases the service life by more than 1 ~ 5 times than that of the valve working at the middle opening and small opening at the beginning. If this method is adopted in a chemical plant, the service life of the valve is increased by 2 times.

Method of reducing s and increasing working opening to improve service life

Reduce s, that is, increase the loss of the system except the regulating valve and reduce the pressure drop distributed to the valve. In order to ensure that the flow passes through the regulating valve, the opening of the regulating valve must be increased. At the same time, the pressure drop on the valve will be reduced, so as to reduce cavitation and erosion.

Specific measures include:

An orifice plate is set behind the valve to throttle the consumption pressure drop;

Close the manual valve in series on the pipeline until the regulating valve obtains an ideal working opening.This method is very simple, convenient and effective when the valve is selected to be large at the beginning and working at a small opening.

Method of reducing caliber and increasing working opening to improve service life

Increase the working opening by reducing the diameter of the valve.

Specific measures include:

Change a valve with a small first gear diameter, such as DN32 to DN25;

If the valve body does not change, replace the valve core and valve seat with small valve seat diameter.

For example, when a chemical plant is overhauled, the throttling part dgl0 is replaced with dg8, and the service life is doubled.

Method of transferring failure location to improve service life

Move the seriously damaged parts to the secondary position to protect the sealing surface and throttling surface of the valve core and valve seat.

Method of increasing throttling channel and improving service life

The simplest way to increase the throttle channel is to thicken the valve seat to increase the valve seat hole and form a longer throttle channel.On the one hand, it can delay the sudden expansion after flow closed throttling, transfer the damage position and keep it away from the sealing surface; On the other hand, it increases the throttling resistance, reduces the recovery degree of pressure and weakens cavitation.

Some design the valve seat hole into step type and wave type in order to increase resistance and weaken cavitation. This method is often used on the high-pressure valve in the imported device and when the old valve is improved, and it is also very effective.

Changing flow direction to improve service life

The flow open type flows in the open direction, and cavitation and erosion mainly act on the sealing surface, causing the valve core root and the sealing surface of the valve core valve seat to be damaged quickly; The flow closed type flows towards the closed direction. Cavitation and erosion act below the sealing surface of the valve seat after throttling, protecting the sealing surface and the root of the valve core and prolonging the service life.

Therefore, when the problem of prolonging the service life of the valve used as flow opening type is more prominent, the service life can be prolonged by 1 ~ 2 times by changing the flow direction.

Using special materials to improve service life

In order to resist cavitation (damage shape, such as honeycomb dots) and scouring (streamlined ditches), special materials resistant to cavitation and scouring can be used to manufacture throttling parts. This special material includes 6yc-1, A4 steel, Stellite, cemented carbide, etc. In order to resist corrosion, materials with more corrosion resistance and 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.).

Method for improving service life by changing valve structure

Change the valve structure or select the valve with longer service life to improve the service life, such as multi-stage valve, anti cavitation valve, corrosion-resistant valve, etc.

Method of reducing stroke to improve diaphragm life

For the two position regulating valve, when the action frequency is very frequent, the diaphragm will soon break in the up and down folding, and the damage position is often on the circumference of the tray.The simplest and most effective way to improve the service life of diaphragm is to reduce the stroke. The reduced stroke value is 1 / 4dg. For example, the standard stroke of dgl25 valve is 60mm, which can be reduced to 30mm, which is shortened by 50%.

In addition, the following factors can be considered:

Reduce the pressure of membrane chamber as much as possible under the conditions of opening and closing;

Improve the smoothness of the joint between the tray and the diaphragm.