What is a Valve?
Before diving into preventing how valve erosion can be prevented, we must understand what a valve is. A valve is a mechanical device that controls the flow of a liquid, gas, or slurry through a systematic passageway such as pipes. A valve achieves control by stopping, varying, or starting the fluid flow, controlling the direction of the flow, regulating process pressure, and relieving over pressure. For example, think of a valve like a faucet in your kitchen or bathroom sink. By turning the handle, you control and flow of the water. For more knowledge on what a valve is, the different types of valves, and the industries they serve; click here.
What is Valve Erosion?
Valve erosion is the gradual wear and tear on valve components due to the abrasive action of a fluid or gas flowing through them. The process may be accelerated due to numerous factors. Such examples are, flow velocities, turbulence, cavitation, and solid particles, such as in slurries. It is a major concern as it can lead to reduced efficiency, increased maintenance costs, and valve failure.
How is Valve Erosion Prevented?
It can be prevented by selecting the right materials, the valve’s design, how the flow is controlled, how the pressure is controlled, the filtration process, and maintenance.
Choosing the Right Material
Using materials that are hard and erosion resistant will help resist wear from high-velocity flow and abrasive particles. For example, tungsten carbide, stainless steel, and ceramics are commonly used to prevent valve erosion.
Flow Control
Designs that minimize turbulence, sharp turns, and sudden expansions/reductions into the flow path can reduce high-velocity impacts. Thus, by controlling the flow of the fluid or gas in a way that reduces sudden pressure drops a reduction of erosion can be achieved.
Pressure Control
Maintaining upstream and downstream pressure to avoid vapor bubbles from forming and collapsing can protect the valve. Hence, by avoiding choke conditions valve operates within its design range causing a concentration of erosive forces into a small area.
Filtration
Erosion is often cause by solid particles in the liquid or gas. Thus, by adding filters and strainers upstream of the valve abrasives can be removed before they cause significant damage.
Maintenance
Regular maintenance checks can catch early signs of erosion and the conditions that promote it. For this reason, erosion can be avoided by proactively replacing the seats, seals, or trims before severe damage occurs will extend the valve’s overall life span.