In the world of valves, ball valves are known for their compact, durable design and reliable, fast acting on/off control. Ball valves utilize a ball with a hole (known as a port) drilled through the center to control the flow of media. The ball is rotated 90 degrees to align the port with the valve body and allow media to flow through the valve. To close the valve, the ball is rotated 90 degrees back to the closed position.

All ball valves rely on the use of two seats, usually made of polytetrafluoroethylene (PTFE), to hold the ball in place and create a tight seal to prevent media from leaking through the valve.

Floating and trunnion are two basic types of ball valve designs. Floating ball valves are the most common type of valve used in industrial piping systems. These valves are designed so that as the seats begin to wear the pressure from the media flowing through the valve will force the ball against the downstream seat to maintain a tight seal.

In trunnion ball valves, the ball is fixed in place by bearings that prohibit it from floating downstream. A spring-loaded seat mechanism ensures that the valve remains leak-tight as the seat inevitably begins to wear down.

Features and Benefits

• The floating ball is
  • Preloaded between the seats during assembly.
  • Moves incrementally tighter against the seats as pressure increases.
  • Provides a reliable positive shut-off in either flowing direction.
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• The removable bonnet design allows for field replacement of the stem seal without removing the valve from the flow line.
• The body injection fitting is used for routine lubrication of the body cavity and injection of emergency sealant. This helps to reduce torque and extend service life.
• Quarter-turn design.
• Available as manual lever, gear operated, or actuated.

Before we dive into the details of floating ball valve design, let's define the key components of a ball valve:

• Valve body - the chamber in which the valve mechanism is encased. Ball valves are commonly made of steel, iron, brass, bronze or PVC.
• Ball - A pivoting sphere with a flow path through the center, connected to the valve body via a stem or shaft
• Bore or port - hollow center of the ball
• Packing - Flexible seals that fit around the valve stem to prevent media from escaping the valve body
• Seat - A round, donut-shaped disc that forms a seal between the valve body and ball
• Stem - The shaft that anchors the ball and connects it to the external operating lever or actuator
• Actuator - An external device designed to rotate the stem of the valve. This can be a lever, a gear, a motor-operated gear (electric actuator) or a pneumatic/hydraulic actuator.

Most ball valves are of the floating variety. Floating ball valves are supported by cupped seats that create a tight seal between the valve body and the ball. The ball itself is suspended in the media it regulates and is kept in position by cup-like seats, usually made of a thermoplastic. These seats form a tight seal between the ball and the valve body.

Floating ball valves are capable of providing bi-directional sealing, meaning that the ball can move freely enough to halt media flowing in either direction. This type of valve is lightweight, economical and versatile, and is found in applications including oil, gas, water, steam and petrochemicals.