Anti-Cavitation Trim Innovation for V-Notch Ball Valves

by , | Apr 26, 2021 | Valves, Actuators & Regulators

Jim Cahill

Chief Blogger, Social Marketing Leader

Many times, we discuss how advancing technology enables breakthrough innovations in Industrial Automation. A recent Oil & Gas Engineering article, Next-gen trim cuts rotary valve cavitation, highlights a great example of this with rotary valve technology.

In this article, Emerson’s Brandon Bell describes how additive manufacturing, based on 3D printing technology advancements, enabled the development and manufacturing of anti-cavitation trim for rotary valves. V-notch ball control valve bodies are well suited to control erosive or viscous fluids, paper stock, or other slurries containing entrained solids or fibers.

Brandon highlights the technology innovation, noting:

…recent advances in additive manufacturing have changed the landscape for anti-cavitation trim designs. Additive manufacturing uses precision-guided lasers and high-hardness alloys to build up valve components in a 3D printing arrangement. This manufacturing technique enables specialized trim designs that would have been impossible or prohibitively expensive to fabricate just a few years ago.

He describes the problems cavitation cause:

Cavitation poses serious problems for control valves, especially in high-flow and high-pressure-drop applications. As a liquid passes through the control valve restriction, increased velocity creates a low-pressure zone downstream of the valve that effectively boils the liquid and creates vapor bubbles in the flow stream.

As the fluid passes beyond the trim and velocity slows, the pressure returns and the vapor bubbles collapse. The implosion of the bubbles creates localized micro jets and shockwaves that can severely damage valve components and piping, especially if the bubble happens to be near a metal surface…

Brandon shared the story of a Louisiana refinery with an application involving:

…a control valve passing large quantities of river water laden with fine silt. The flow rates and line size demanded a rotary valve, and the pressure drop across the valve was high.

Due to damage from cavitation and erosion:

…the control valve was replaced every 24 months, and the downstream piping was replaced every six to twelve months.

Fisher Vee-ball rotary control valve with Cavitrol Hex anti-cavitation trimUsing the additive manufacturing process, a Cavitrol Hex anti-cavitation trim was available for the Fisher Vee-ball rotary control valve for use in this demanding application. He highlighted the innovation in this trim design.

Unlike previous designs, this rotary valve anti-cavitation trim is inserted into the valve from the downstream side and is not connected to the rotating ball in any way, allowing the trim to perform as desired to reduce cavitation regardless of the degree of valve opening. It also can be retrofitted and installed into any existing Fisher Vee-ball valve.

Read the article for how this Louisiana refinery successfully installed the valve and trim to reduce the effects from cavitation and the conditions of the valve and downstream piping after a year in service.

Visit the Segmented Ball Valves section on Emerson.com for more on these rotary valves and trim offerings that provide good rangeability, control, and shutoff capability. You can also connect and interact with other rotary valve experts in the Valves, Actuators & Regulators group in the Emerson Exchange 365 community.

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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.