Guide to Choosing Between Floating and Trunnion Ball Valves

Ball valves are quarter-turn valves that utilize a spherical disc with a circular bore to control fluid flow. Their simple structure, easy operation, and excellent sealing performance make them widely applicable across various industrial sectors. By rotating the ball 90 degrees, the valve opens or closes - when the bore aligns with the pipeline, fluid flows freely; when perpendicular, flow is blocked.

The concept of ball valves dates back to the 19th century, but it wasn't until mid-20th century advancements in materials science and manufacturing technology that they became prevalent in industrial applications. Early designs were relatively simple, primarily for low-pressure uses. As industries like petroleum and chemicals rapidly developed, demanding high-pressure, high-temperature, and corrosion-resistant solutions, ball valve technology significantly improved.

Ball valves are categorized by design characteristics and application scenarios, with the most common types including:

• Floating Ball Valves
• Trunnion Ball Valves
• V-Port Ball Valves
• Three-Way Ball Valves
• Welded Ball Valves

This article focuses on floating and trunnion ball valves, analyzing their differences and appropriate applications.

Floating ball valves feature a ball that isn't fixed but "floats" between two seats. Connected only via the stem to the actuating mechanism, pipeline pressure forces the ball against the downstream seat to create sealing.

When medium pressure acts on the ball, pressure differential forces it against the downstream seat, generating sealing force. As pressure increases, so does sealing force, ensuring valve integrity. Since the ball must overcome pipeline pressure to rotate, operating torque rises significantly with larger diameters and higher pressures.

• Simple structure: Fewer components make them easier to manufacture and maintain.
• Lower cost: Simple design translates to reduced manufacturing expenses.
• Good sealing: Effective for most medium-low pressure applications.

• High torque requirements: Larger diameters or higher pressures dramatically increase operating torque.
• Limited applicability: High pressure/temperature may cause seat wear, especially with metal seats.
• Pressure sensitivity: Sealing performance may fluctuate with significant pressure variations.

Ideal for medium-low pressure, small-diameter scenarios including:

• Civil construction (water supply, heating systems)
• Light industry (food/beverage production lines)
• General industry (water treatment, gas distribution)

Trunnion ball valves feature a ball fixed by upper/lower pivots (trunnions), preventing free movement. Seats are spring- or pressure-loaded against the ball for sealing.

Fixed trunnions eliminate ball displacement under pressure. Seats provide sealing force via springs or medium pressure. Since the ball doesn't bear pipeline pressure, operating torque remains low even for large diameters or high pressures.

• Reduced torque: Easier manual/automated operation.
• Wider applicability: Suitable for demanding high-pressure, large-diameter, high-temperature conditions.
• Extended lifespan: Reduced seat friction increases durability.
• Enhanced safety: Some models include pressure relief features.
• Superior sealing: More stable performance under high pressure.

• Complex structure: More components increase manufacturing costs.
• Maintenance complexity: More intricate design requires specialized servicing.

Designed for demanding conditions including:

• Oil/gas (transmission, refining systems)
• Chemical processing (material transfer, reactors)
• Power generation (steam/water circulation)
• Metallurgy (steel production processes)

Material choice critically impacts valve performance, lifespan, and applicability:

Body Materials:

• Carbon Steel: Good strength/toughness for general use
• Stainless Steel: Excellent corrosion resistance
• Alloy Steel: Enhanced strength/heat resistance
• Plastic: Corrosion-resistant, lightweight for low-pressure uses

Seat Materials:

• PTFE: Superior chemical resistance/low friction
• Reinforced PTFE: Improved wear/pressure resistance
• Metal: For extreme temperatures/pressures

Primary operation modes include:

• Manual: Handwheel or lever operation
• Pneumatic: Compressed air actuation
• Electric: Motor-driven operation
• Hydraulic: Fluid-powered actuation

Selection depends on operating conditions, frequency, and automation requirements.

Proper procedures ensure optimal performance and longevity.

Installation Notes:

• Thoroughly clean pipelines before installation
• Align piping connections precisely
• Torque fasteners to specifications
• Observe flow direction indicators

Maintenance Notes:

• Regularly inspect sealing, operation, and connections
• Lubricate moving components periodically
• Clean internal passages to remove debris
• Replace worn/damaged parts promptly

Ongoing technological advancements drive innovation in:

• Smart functionality: Integrated sensors for remote monitoring
• Weight reduction: Advanced materials for easier handling
• Flow efficiency: Optimized passage designs
• Environmental focus: Eco-friendly materials/processes

Both floating and trunnion ball valves serve distinct purposes - floating valves excel in economical, low-pressure applications, while trunnion valves deliver superior performance in demanding conditions. Proper selection considering operational parameters, medium characteristics, safety requirements, and budget ensures optimal system performance, safety, and cost-efficiency.