STEM

Ball Valve Part: Stem

The stem is a vital component of a ball valve that connects the actuator or handle to the ball, enabling rotational movement to open or close the valve. It transmits the torque applied externally to rotate the ball inside the valve body, controlling flow through the pipeline.

Function of the Stem

• Torque Transmission
  The stem transfers the turning force from the valve handle, gear, or actuator to the ball, causing it to rotate 90 degrees for on/off operation or partial rotation for throttling.

• Sealing Interface
  The stem passes through the valve body and must be sealed properly to prevent leaks. This is typically achieved through packing materials, O-rings, or gland seals.

• Alignment and Support
  Provides axial alignment between the actuator and the ball, ensuring smooth, precise valve operation.

Key Features

• Material
  Usually made of stainless steel, carbon steel, or alloy steel to withstand mechanical stress and corrosion.

• Stem Types

  • Blowout-Proof Stem: Designed to prevent the stem from being ejected under pressure.

  • Non-Rising Stem: Rotates in place without axial movement, saving space.

  • Rising Stem: Moves axially during operation, providing a visual indicator of valve position.

• Sealing Mechanisms
  Incorporates packing, O-rings, or gland seals to maintain tightness around the stem and prevent leakage.

Applications

• Integral to all ball valves across industries such as oil & gas, chemical processing, water treatment, and power generation.

• Designed to accommodate manual, electric, pneumatic, or hydraulic actuation.