How to Extend the Lifespan of Control Valves?

01. High-Opening Operation

Let the control valve work at a high opening from the beginning, such as 90%. In this way, cavitation, erosion, and other forms of damage will occur mainly at the valve core tip.

As the valve core is damaged, the flow rate increases, and the valve gradually closes slightly. This process continues, progressively closing the valve and fully utilizing the entire valve core, until the core root and sealing surfaces are damaged and the valve can no longer be used.

At the same time, high opening results in a larger throttling gap, which reduces erosion. This can extend the valve’s life by 1-5 times compared to starting at the middle or small opening. For instance, a chemical plant using this method doubled the valve's lifespan.

02. Reduce the Valve Resistance Ratio (or Pressure Drop Ratio) “S”

Reducing “S”, which means increasing the system losses excluding the control valve, decreases the pressure drop across the valve. To maintain the flow through the valve, the valve opening must increase, while the pressure drop across the valve decreases, reducing cavitation and erosion.

Specific methods include: installing a throttling orifice plate after the valve to consume pressure drop; or closing manual valves in the pipeline to adjust the control valve to its optimal working position. This method is very simple, convenient, and effective for valves initially working at small openings.

03. Reduce the Diameter and Increase the Working Opening

By reducing the valve’s diameter, the working opening can be increased. Specific methods include:

Replacing the valve with a smaller size, for example, replacing a DN32 valve with a DN25 one.

Keeping the valve body unchanged and replacing the valve seat diameter with a smaller one. For example, during a plant overhaul, a chemical plant replaced the throttling component dg10 with dg8, which doubled the valve’s lifespan.

04. Shift the Damage Location

Move the most severely damaged parts from critical locations to less important ones in order to protect the sealing surfaces and throttling surfaces of the valve core and valve seat. This can improve the valve's lifespan.

05. Change the Flow Direction

In the open-flow type, the flow moves in the direction of the valve core opening, and cavitation and erosion primarily affect the sealing surfaces, quickly damaging the valve core and valve seat sealing surfaces. In the closed-flow type, the flow moves in the direction of valve closure, and cavitation and erosion affect the throttling area after the flow, protecting the sealing surfaces and valve core root, extending the valve’s life.

Note: Changing from open-flow to closed-flow may cause valve "chatter" (when the valve is opened), and the presence of vortices can affect the control system, making the regulation unstable. This method must be carefully considered and evaluated comprehensively.

06. Use Special Materials

To resist cavitation (which causes honeycomb-like small holes) and erosion (which creates streamlined grooves), special materials that are resistant to cavitation and erosion can be used for throttling components.

These special materials include 6YC-1, A4 steel, Stellite, hard alloys, etc. For corrosion resistance, more corrosion-resistant materials with good mechanical and physical properties, such as rubber, Teflon, ceramics, Monel, and Hastelloy alloys, can be used.

07. Properly Select the Valve Structure

Changing the valve structure or selecting valves with longer lifespans can improve longevity. For example, using labyrinth valves, multi-stage valves, anti-cavitation valves, and corrosion-resistant valves.

The advantages of control valves during use are:

Quick action, able to promptly complete various adjustment commands.

When used with pneumatic actuators, they provide a large driving force.

Stable performance in harsh working environments, ensuring normal operation.

High safety performance.

The proper functioning and responsiveness of control valves have a direct impact on production quality and efficiency. Therefore, analyzing and solving the factors affecting valve failures during operation is particularly important.