Views: 0 Author: Site Editor Publish Time: 2025-01-07 Origin: Site
Ball valves are a major segment of valve types that control flow in various ways across industries that include oil, gas, and more importantly, water treatment. Floating ball and trunnion ball valves, among other types of ball valves, are particularly popular with different designs and applications. But how do they differ from each other? Which one is the best for you?
In this post, you will get to learn the primary differences between floating and trunnion ball valves. We will also include information such as features, pros and cons, and suitable applications for each of the discussed valves. By the end of this reading, one would have acquired enough knowledge to choose the best valve among the two for specific applications.
Ball valves are versatile devices that control fluid flow in pipelines. They use a spherical ball, featuring a hole through the center, to start or stop fluid movement. The simplicity and efficiency of their design make them widely used in various industries.
The valve’s ball rotates within the housing. When aligned with the pipeline, the hole in the ball allows fluid to flow freely. Rotating the ball 90 degrees blocks the flow. This quarter-turn actuation provides quick and reliable control.
Ball valves are found in industries like:
Oil and Gas: Regulating pipelines and refining systems.
Chemical Processing: Ensuring safe handling of corrosive fluids.
Water Treatment: Managing water distribution and filtration systems.
HVAC: Controlling heating and cooling systems.
They are also popular in residential plumbing due to their ease of use and durability.
Compared to other valve types, ball valves offer:
Full Bore Design: Minimal flow resistance for maximum efficiency.
Tight Sealing: Prevents leakage, even under high pressure.
Ease of Operation: Quick quarter-turn actuation reduces effort.
Versatility: Suitable for liquids, gases, and slurries.
A floating ball valve is a type of valve that uses a ball to control the flow of fluids through a pipe. The ball in a floating ball valve is designed to "float" between two seats inside the valve body.
In a floating ball valve, the ball is not fixed to the valve stem. Instead, it is free to move or "float" between the two seats. When the valve is open, the ball floats freely, allowing fluid to flow through the valve.
When the valve is closed, upstream pressure pushes the ball against the downstream seat. This creates a tight seal that prevents fluid from passing through. The higher the pressure, the tighter the seal becomes.
Floating ball valves have a simple, reliable design. They consist of:
Valve body
Floating ball
Two seats (upstream and downstream)
Stem and handle for opening/closing
The ball typically has a hole or port drilled through the center to allow fluid to flow when aligned with the pipe. Rotating the ball 90° blocks flow.
Floating ball valves are available in a wide range of sizes, typically from 1/4" to 12". They are commonly used in low to medium pressure applications up to around ANSI Class 600 (1440 psi).
The materials used to make floating ball valves depend on the application and the type of fluid being handled. Common materials include:
Carbon steel
Stainless steel
Brass
PVC
CPVC
The ball and seats are often coated or made of different materials for improved wear and sealing.
Floating ball valves are well-suited for a variety of applications, such as:
Water and wastewater systems
Low to medium pressure gas lines
Chemical processing
Petroleum products
General industrial use
They are often used for on-off or isolation service rather than throttling or flow control.
Some key advantages of floating ball valves include:
Simple, reliable design with few moving parts
Cost-effective, especially in smaller sizes
Provide good shutoff and a bubble-tight seal
Easy to operate and maintain
Durable with long service life
Floating ball valves also have some limitations, such as:
Limited to low and medium pressure applications
Can be difficult to operate if pressure is too high
More prone to leakage than trunnion-mounted ball valves
Not ideal for frequent cycling or throttling service
Larger sizes can be heavy and expensive
A trunnion ball valve is a type of ball valve designed for high-pressure and critical applications. Unlike floating ball valves, the ball in a trunnion valve is fixed in place and does not move or "float" within the valve body.
In a trunnion-mounted ball valve, the ball is supported by trunnion bearings on the top and bottom. These bearings hold the ball securely in place, preventing any movement.
The valve seats are spring-loaded and situated on both the upstream and downstream sides of the ball. When the valve is closed, the springs push the seats tightly against the ball, creating a strong seal on both sides. This double seal design provides superior leak protection compared to floating ball valves.
Key design features of trunnion-mounted ball valves include:
Sturdy trunnion bearings to support the ball
Double block and bleed capability for added safety
Spring-loaded seats for tight shutoff
Anti-static design to prevent electric charge buildup
Full or reduced bore options
Fire-safe construction available
The trunnion design allows them to operate at higher pressures and temperatures than floating ball valves.
Trunnion ball valves are commonly available in sizes from 2" to 60" or larger. They can handle pressures up to ANSI Class 2500 (5500 psi) and beyond, making them suitable for the most demanding applications.
Due to their use in high-pressure and severe service applications, trunnion ball valves are typically made from robust materials such as:
Carbon steel
Stainless steel
Duplex or super duplex stainless
Alloy 20, Hastelloy, Inconel, and other exotic alloys
The ball and seats may be coated with tungsten carbide, chrome carbide, or other hard materials for enhanced wear resistance.
Trunnion ball valves are well-suited for demanding applications, including:
Oil and gas pipelines, processing facilities, and offshore platforms
Chemical and petrochemical plants
Power plants, including high-pressure steam service
Hydrocarbon processing and refining
Mining and mineral processing
They are often used for critical isolation and emergency shutdown (ESD) service where reliable, leak-tight performance is essential.
Some key benefits of trunnion-mounted ball valves are:
Ability to handle high pressures and temperatures
Lower operating torque compared to floating ball valves
Minimal leakage and excellent sealing, even in gas service
Robust construction for long service life in severe conditions
Increased safety with double block and bleed capability
Trunnion ball valves also have some drawbacks, such as:
More complex design with additional parts like bearings and springs
Higher cost, especially in larger sizes
Require more frequent maintenance to keep them in top operating condition
Larger and heavier than floating ball valves, requiring more space
While floating ball valves and trunnion ball valves share some similarities, they also have important differences. This section provides a side-by-side comparison of their key features and specifications.
| Feature | Floating Ball Valve | Trunnion Ball Valve |
|---|---|---|
| Pressure Rating | Up to ANSI Class 600 | Up to ANSI Class 2500 or higher |
| Temperature Limits | -50°F to 450°F | -150°F to 1000°F |
| Valve Torque | Higher, increases with pressure | Lower, consistent across pressure range |
| Ease of Operation | Can be difficult at high pressures | Easier to operate at all pressures |
| Shutoff Capability | Good, but may leak over time | Excellent, reliable long-term shutoff |
| Size Range | 1/4" to 12" | 2" to 60" or larger |
| Weight | Lighter, especially in larger sizes | Heavier due to trunnion and bearings |
| Materials | Carbon steel, stainless steel, brass, plastic | Carbon steel, stainless steel, exotic alloys |
| Maintenance | Less frequent, easier to maintain | More frequent, requires skilled technicians |
| Price | Lower, especially in smaller sizes | Higher, due to complex design and materials |
As the table shows, trunnion ball valves can handle much higher pressures and temperatures than floating ball valves. They also provide better shutoff capability and require less torque to operate, particularly at high pressures.
However, trunnion ball valves are typically larger, heavier, and more expensive than floating ball valves. They also require more frequent maintenance by skilled technicians to keep them operating at peak performance.
Floating ball valves are a good choice for lower pressure applications where cost is a concern. They are available in a wider range of materials, including plastics, making them suitable for handling corrosive fluids.
In summary, the key differences between floating and trunnion ball valves include:
Pressure and temperature ratings
Valve torque and ease of operation
Shutoff capability and reliability
Size and weight
Materials of construction
Maintenance requirements
Price
When selecting between a floating ball valve and a trunnion ball valve, it's important to consider the specific needs of the industry and application. Different industries have different requirements for pressure, temperature, reliability, and cost.
Floating ball valves are a popular choice for general-purpose applications and industries that involve lower pressures and less demanding service conditions. Some common industries and applications that favor floating ball valves include:
Water and wastewater treatment
Irrigation and agriculture
Heating, ventilation, and air conditioning (HVAC)
Food and beverage processing
Pulp and paper mills
Mining and mineral processing
General industrial applications
These industries often have lower pressure requirements, typically up to ANSI Class 600 (1440 psi). Floating ball valves provide a cost-effective solution for these applications while still offering reliable shutoff and control.
Trunnion ball valves are designed for more demanding industries and applications that involve high pressures, extreme temperatures, and critical service conditions. Industries that commonly use trunnion ball valves include:
Oil and gas production, pipelines, and refineries
Chemical and petrochemical processing plants
Power generation, including nuclear and fossil fuel plants
Offshore platforms and subsea installations
Liquefied natural gas (LNG) and cryogenic service
High-pressure steam systems
These industries require valves that can handle pressures well above ANSI Class 600, often up to ANSI Class 2500 (5500 psi) or higher. Trunnion ball valves are designed to withstand these extreme conditions while providing reliable, leak-tight performance.
The table below summarizes the key industries and applications for floating and trunnion ball valves:
| Floating Ball Valves | Trunnion Ball Valves |
|---|---|
| Water and wastewater | Oil and gas |
| Irrigation and agriculture | Chemical and petrochemical |
| HVAC | Power generation |
| Food and beverage | Offshore and subsea |
| Pulp and paper | LNG and cryogenic |
| Mining and mineral processing | High-pressure steam |
| General industrial | Critical service |
While there may be some overlap between industries, this table provides a general guideline for which types of ball valves are most commonly used in each sector.
Selecting the right ball valve is critical for ensuring system performance and reliability. By evaluating factors such as pressure, fluid type, and operational needs, you can make an informed decision.
Floating ball valves work well for low to medium pressure systems, handling water, gas, or light chemicals.
Trunnion ball valves excel in high-pressure environments, managing corrosive or high-temperature fluids with ease.
Frequent cycling demands a robust design. Trunnion valves are better suited for systems requiring regular operation.
For less frequent use, floating valves provide an economical and reliable choice.
If a bubble-tight seal is essential, both types can deliver, but trunnion valves are more effective in high-pressure scenarios.
Floating valves are sufficient for systems with moderate shutoff requirements.
Floating ball valves are compact, making them ideal for smaller pipelines.
Trunnion valves accommodate larger diameters, offering stability and reduced torque in large-scale applications.
Leakage risks are higher in floating ball valves under elevated pressures.
Trunnion ball valves are designed to minimize leakage, even in critical applications.
Floating ball valves offer lower upfront costs, especially for smaller systems.
Trunnion valves have higher initial expenses but offer better durability and lower lifecycle costs in demanding environments.
For non-critical applications like water distribution, floating valves are sufficient.
Critical systems, such as oil and gas pipelines, require the reliability and robustness of trunnion ball valves to prevent failures.
In summary, when choosing between a floating and trunnion ball valve, consider the following factors:
Pressure, temperature, and fluid compatibility
Frequency of operation and cycling
Shutoff requirements (bubble-tight or not)
Size of the pipe and valve
Importance of preventing leakage
Upfront cost vs. total lifecycle cost
Criticality of the application and consequences of failure
Floating and trunnion ball valves differ in design, performance, and cost. Floating valves are simple, economical, and ideal for lower pressure applications. Trunnion valves are robust, better for high-pressure systems, but come with higher costs.
Choosing the right valve depends on factors like pressure, fluid type, and system requirements. Floating valves suit general-purpose systems, while trunnion valves are perfect for critical, high-pressure applications.
Work with RST Valve experts to choose the right valve for your needs. Their experience and global standards ensure reliable solutions for any application. Contact them today to optimize your system's performance.
The choice between a floating and trunnion ball valve depends on several factors, including the pressure, temperature, and type of fluid being handled, as well as the frequency of operation, shutoff requirements, and criticality of the application. In general, floating ball valves are suitable for lower pressure, less demanding applications, while trunnion ball valves are better suited for high-pressure, critical service conditions.
Floating ball valves are commonly available in sizes from 1/4" to 12", while trunnion ball valves are typically available in sizes from 2" to 60" or larger. The size of the valve selected will depend on the size of the pipe and the flow requirements of the application.
Yes, floating ball valves can be automated with various types of actuators, including electric, pneumatic, and hydraulic actuators. Automating a floating ball valve can provide remote control, improved efficiency, and faster response times compared to manual operation.
Trunnion ball valves can be designed with either metal or soft seats, depending on the application requirements. Metal seats, such as those made from stainless steel or Stellite, provide greater durability and temperature resistance, while soft seats, such as those made from PTFE or other polymers, provide better sealing and lower operating torque. The choice of seat material will depend on factors such as the fluid type, temperature, and pressure.
Several industry standards cover the design, manufacturing, and testing of floating and trunnion ball valves, including:
API 6D: Specification for Pipeline and Piping Valves
API 608: Metal Ball Valves - Flanged, Threaded, and Welding Ends
ASME B16.34: Valves - Flanged, Threaded, and Welding End
MSS SP-110: Ball Valves Threaded, Socket-Welding, Solder Joint, Grooved and Flared Ends
ISO 17292: Metal ball valves for petroleum, petrochemical and allied industries
These standards ensure that ball valves meet specific requirements for materials, dimensions, pressure ratings, testing, and quality control.
The service life of a floating or trunnion ball valve depends on various factors, such as the application conditions, frequency of operation, and maintenance practices. In general, a well-maintained ball valve can last for many years, with some valves providing reliable service for decades.
Factors that can impact the service life of a ball valve include:
Corrosion or erosion from the process fluid
Wear on the seats and seals from frequent cycling
Damage from debris or contamination in the fluid
Improper installation or maintenance practices
Regular maintenance, such as lubrication, seal replacement, and inspection, can help extend the life of both floating and trunnion ball valves. In general, trunnion ball valves may have a longer service life in demanding applications due to their more robust construction and superior sealing capabilities.
