Introduction
If you’re researching ball valves for an industrial or process piping system, you’ve likely come across the term “floating ball valve“. But what exactly does it mean when the ball “floats”? And how does that affect sealing, pressure handling, and application suitability?
In this article, I’ll break down:
- What defines a floating ball valve
- How it functions under fluid pressure
- How it compares with the trunnion-mounted type
- When and where you should (and shouldn’t) use it
- Common questions engineers and buyers ask when specifying one
Let’s start with the basic structure.
What Is a Floating Ball Valve?
A floating ball valve is a type of quarter-turn valve in which the ball is not physically fixed by a stem or shaft at both ends. Instead, it “floats” within the valve body, held in place only by the pressure of the valve seats.
This allows the ball to move slightly downstream under the pressure of the fluid, pressing against the downstream seat to create a tight seal.
Key features include:
- Two-piece or three-piece construction
- A hollow ball with a through-hole (bore)
- A single top-mounted stem that rotates the ball
- Sealing achieved through ball movement, not seat movement
This floating design works particularly well in low to medium pressure systems where bi-directional sealing is required without the added complexity or cost of a trunnion assembly.
How Floating Ball Valves Work
The key to a floating ball valve’s operation lies in its pressure-activated sealing mechanism. Unlike trunnion-mounted valves, where the ball remains fixed and the seat moves to create a seal, a floating ball valve relies on ball displacement to seal off the flow.
Here’s how it works step by step:
Operating Principle
- Fluid enters the valve body under pressure
- The pressure causes the ball—held loosely between two seats—to move slightly downstream
- This movement pushes the ball tightly against the downstream seat
- The resulting compression creates a seal that prevents leakage
This method enables a reliable shutoff, even with relatively simple construction and a single stem.
Bi-directional Sealing (with Limits)
Most floating ball valves offer bi-directional sealing, meaning they can block flow from either direction. However, the sealing quality is typically better in the direction of pressure due to the downstream movement of the ball.
Some designs include secondary sealing aids, like:
- Spring-loaded seats to enhance contact
- Soft or elastomeric seat materials for better adaptability
- Anti-static devices for gas applications
Torque Consideration
Because the ball shifts during operation, floating ball valves usually require more torque to operate than trunnion valves—especially under high pressure.
This is important when selecting actuators or manual operation strategies, particularly in:
- Automated valve systems
- High-pressure fluid lines
- High-viscosity applications
Summary
A floating ball valve seals by allowing the ball to move downstream and press into the seat—simple, effective, and compact for many common industrial uses.
Floating vs Trunnion Ball Valve: Key Differences
While both floating and trunnion ball valves serve the same basic purpose—shutoff control—they differ significantly in structure, sealing mechanism, and application range.
Understanding these differences is essential for choosing the right valve for your system.
Structural Difference
- Floating Ball Valve:
- The ball is held in place by the valve seats only
- It “floats” slightly downstream when pressurized
- Connected to a single stem on top
- Typically simpler and more compact
- Trunnion-Mounted Ball Valve:
- The ball is held in place by two shafts (top and bottom)
- It does not move—instead, the seats are spring-loaded or pressure-driven toward the ball
- Provides more rigid control and stable positioning
Sealing Mechanism
- Floating Ball:
- Relies on ball displacement toward the seat
- May suffer from overpressure deformation
- Seal tightness depends on line pressure
- Trunnion Ball:
- Ball is fixed
- Seats move toward the ball using pressure or springs
- Provides more stable sealing under high pressure
Operating Torque
- Floating ball valves require higher torque, especially as pressure increases
- Trunnion valves have lower torque demands, making them ideal for automation and large diameter systems
Size and Pressure Range
| Parameter | Floating Ball Valve | Trunnion Ball Valve |
|---|---|---|
| Size Range | Small to medium (< DN150) | Medium to very large (> DN150) |
| Pressure Range | Low to medium (Class 150–300) | Medium to high (up to Class 2500) |
| Torque Demand | High | Lower |
| Complexity | Simple | More complex |
| Cost | Lower | Higher (but justified at scale) |
Application Match Summary
- Choose floating if:
- You need a compact, economical solution
- Your system is low-to-mid pressure
- You’re working with clean, non-abrasive media
- Choose trunnion if:
- You’re handling high-pressure or large-diameter systems
- Automation or low torque is required
- You want longer seat life and stable operation
Summary
Floating = compact, cost-effective, and simple
Trunnion = rugged, pressure-stable, and automation-friendly
Where and When to Use Floating Ball Valves
Floating ball valves are versatile, reliable, and cost-effective—but like any valve type, they shine only in the right applications. Understanding where they work best (and where they don’t) helps avoid performance issues and costly replacements.
Recommended Applications
Floating ball valves are ideal for:
- Small to medium diameter pipelines (typically DN15–DN150)
- Low to medium pressure systems (Class 150–300)
- Bi-directional shutoff requirements
- Manual operation or infrequent actuation
Typical fluid types include:
- Water
- Compressed air
- Light oils
- Natural gas
- Clean process fluids
Industries where floating ball valves are commonly used:
- Water treatment
- HVAC
- Food and beverage (non-viscous media)
- General chemical process lines
- Gas distribution pipelines
Not Recommended For
Avoid floating ball valves in the following situations:
- Very high-pressure systems
- Excessive pressure can deform the ball or seat, leading to leaks
- Large-diameter pipelines (> DN150)
- Torque required to operate becomes excessive
- High-cycling systems (frequent open/close operations)
- Causes accelerated wear of the seat
- Slurry or particulate-laden fluids
- Solid materials can prevent full sealing or scratch the ball surface
- Throttling applications
- Not designed for partial opening—risk of seat erosion
Application Tip
If you’re working within normal industrial service conditions—like clean fluid at moderate pressure—a floating ball valve is usually the best mix of performance and value.
However, for more extreme or specialized conditions, consider moving up to a trunnion-mounted design.
Pros, Limitations, and When Not to Use Them
Floating ball valves have earned their place in many process systems for good reason—but they’re not perfect for every situation. Here’s a breakdown of what they do well, where they fall short, and how to decide if they’re the right fit for your system.
Advantages of Floating Ball Valves
- Simple design
- Fewer moving parts and no bottom shaft = easy to maintain
- Compact and lightweight
- Ideal for space-limited installations
- Cost-effective
- Lower price than trunnion ball valves in most sizes
- Bi-directional sealing
- Can block flow in either direction when properly installed
- Fast shutoff
- Quarter-turn operation allows for quick open/close
Limitations of Floating Ball Valves
- Pressure-dependent sealing
- Rely on system pressure to push ball into seat—may be ineffective in low-pressure conditions
- Higher torque requirements
- Friction between the ball and seats can increase torque, especially under high pressure
- Size and pressure limitations
- Generally not suitable for large diameters or high-pressure classes (above Class 300)
- Not suited for throttling
- Partial open positions can cause seat damage and turbulent flow
- Potential deformation
- In high-pressure or dirty systems, the ball can become misaligned or stuck
Table: Summary of Pros and Cons
| Category | Advantages | Limitations |
|---|---|---|
| Cost | Lower cost design | Less durable in aggressive environments |
| Operation | Simple, fast-acting | More torque required than trunnion |
| Sealing | Bi-directional sealing | Pressure-dependent, less stable under stress |
| Application | Great for general-purpose use | Not ideal for high-cycling or throttling |
| Cost | Lower | Higher (but justified at scale) |
When Not to Use Floating Ball Valves
- Systems operating above 600 psi (Class 600+)
- Lines requiring precision flow control or variable flow
- Fluids with abrasive solids (e.g. slurry, wastewater)
- High-frequency actuation (automated systems with frequent open-close cycles)
- Systems that need very low operating torque (e.g. remote-actuated pipelines)
Summary
Floating ball valves offer a great balance of simplicity and sealing performance—but for high-demand systems, they may not be the right choice. Know your limits before committing.
FAQs About Floating Ball Valves
Below are answers to some of the most frequently asked questions about floating ball valves—covering definition, use cases, performance, and comparison with other designs.
Why is it called a “floating” ball valve?
Because the ball is not rigidly held by shafts at both ends—it is “floating” between the valve seats. Under pressure, it moves slightly downstream to press against the seat and create a seal.
Are floating ball valves bi-directional?
Yes—most are designed for bi-directional sealing, meaning they can block flow in either direction.
However, the sealing effectiveness may be better in the direction of flow pressure, since the ball presses into the downstream seat.
Can floating ball valves handle high pressure?
Only to a degree. Floating ball valves typically handle up to Class 300 (around 600 psi) reliably. For higher-pressure systems, trunnion-mounted ball valves are recommended due to better ball support and lower operating torque.
Is a trunnion ball valve better than a floating ball valve?
It depends on your application.
- Trunnion valves are better for high pressure, large diameter, or automated systems.
- Floating valves are ideal for smaller pipelines, moderate pressure, and lower-cost installations.
Can I use a floating ball valve for throttling?
No. Floating ball valves are on/off devices only.
Operating them in a partially open position can damage the seats and cause leak paths due to turbulence and seat wear.
How do I know if I need floating or trunnion valves?
Ask yourself:
- Is my system under moderate pressure and less than 6 inches in diameter? → Floating
- Is it high pressure, automated, or over DN150? → Trunnion
Still unsure? → Contact XHVAL’s engineering team for expert assistance.
Conclusion: Know When Floating Ball Valves Work—and When They Don’t
Floating ball valves are a proven and reliable choice for many industrial systems. Their simple construction, bi-directional sealing, and cost-effectiveness make them an excellent solution for low to medium pressure pipelines handling clean liquids or gases.
But no valve is universal.
Before choosing a floating ball valve, be sure to ask:
- Will the system experience high pressure or frequent cycling?
- Is throttling control required?
- Am I dealing with abrasive or particulate-laden media?
If the answer to any of these is “yes,” then you may need to explore alternatives like trunnion-mounted ball valves.
Quick Recap: When to Use Floating Ball Valves
| Use Case | Recommended? | Notes |
|---|---|---|
| Low- to medium-pressure systems | ✅ | Ideal sealing performance with clean fluids |
| Bi-directional shutoff needs | ✅ | Works well in both flow directions |
| Large-diameter or high-pressure | ❌ | Use trunnion-mounted instead |
| Abrasive fluids or slurries | ❌ | Can damage seats and misalign ball |
| Throttling or flow control | ❌ | Not designed for partial open positions |
Need Help Choosing the Right Valve?
At XHVAL, we offer both floating and trunnion-mounted ball valves, engineered for durability and optimized flow control across industries. If you’re unsure which type is best for your application:
→ Explore Our Full Ball Valve Portfolio
→ Contact Our Engineering Team to get personalized advice and specification support
Make the right choice—avoid performance risks and extend your system’s life cycle with expert-backed valve solutions.