The Physics of “Wire Drawing” & Gate Valve Failure

Jul 27, 2026

The Science of Wire Drawing: Why Throttling Destroys Industrial Gate Valves

The Common Operational Mistake: Throttling Isolation Valves

Walk through almost any mineral processing plant or municipal pump station in South Africa, and you are likely to spot a wedge gate valve wound down to a $30\%$ or $40\%$ open position. Typically, this is a quick fix by an operator trying to restrict flow from an oversized pump.

While it temporarily solves the flow issue, it triggers an aggressive, destructive physical phenomenon known in fluid dynamics as wire drawing.

What is Wire Drawing? The Fluid Dynamics Explained

Standard gate and knife gate valves are engineered for binary operation: they must be either fully open or fully closed. When you partially close a gate to throttle flow, you restrict the fluid’s path, forcing it through a narrow, crescent-shaped aperture beneath the gate.

In a high-velocity jet stream:

  1. Cavitation Micro-Jets: The localized pressure drop can fall below the vapor pressure of the liquid, causing vapor bubbles to form and violently collapse against the metal, eroding the seating faces.

  2. Physical Wire Cutting: The high-velocity liquid jet—especially if carrying fine suspended solids—acts like a physical wire saw. It cuts deep, precise grooves across the metal seats. Once these grooves (or “wire draws”) form, the valve can never achieve a tight shut-off again, rendering the isolation point useless.

[Fluid Flow] ---> || (Partially Closed Gate)
                  ||
                 _||_   <-- High-Velocity Jet (Spike in Velocity)
               /      \ 
              |  Seat  | <-- Cavitation & Grooving (Wire Drawing Area)

How to Prevent Wire Drawing in Your Plant

  • Match Valve Design to Duty: If your process line requires continuous flow adjustment, bypass the gate valve entirely. Implement a specialized, polyurethane-lined pinch valve or an eccentric plug valve designed to handle throttling turbulence without seat erosion.

  • Address the Root Cause: If a pump is consistently oversized, throttling the discharge valve is an inefficient energy sink. Invest in a Variable Speed Drive (VSD) to modulate flow electronically, protecting your physical pipeline assets.