Trunnion Mounted Ball Valve for Energy Industry Applications

A trunnion mounted ball valve is one of the most widely used isolation valve types in the global energy sector.

From upstream oil and gas production to midstream pipelines and downstream petrochemical and power plants,

this valve design offers reliable shut-off, low operating torque and long service life under demanding conditions.

The following guide explains what a trunnion mounted ball valve is, how it works, where it is used, and what

engineers and specifiers should consider when selecting this valve type for energy industry applications.

What Is a Trunnion Mounted Ball Valve?

A trunnion mounted ball valve is a quarter-turn valve in which the ball is mechanically supported at both the

top and bottom by trunnions (stub shafts). These trunnions hold the ball firmly in position, while the line

pressure drives the floating seats against the ball to achieve tight sealing. Unlike a floating ball valve,

the ball in a trunnion design does not move downstream under pressure; instead, it rotates around its axis,

supported by bearings and trunnions.

In energy industry pipelines, process units and utility systems, the trunnion mounted ball valve is widely

selected for high-pressure, large-diameter and severe service applications where tight shut-off, bubble-tight

sealing and low operating torque are essential for safe and efficient operation.

Key Features of Trunnion Mounted Ball Valves

For energy industry engineers and maintenance teams, the most important features of trunnion mounted ball valves include:

• Quarter-turn operation: 90-degree rotation from fully open to fully closed.
• Top and bottom trunnion support: Ball supported to reduce bending and minimize load on the stem.
• Spring-loaded floating seats: Seats are energized against the ball for reliable sealing at low and high pressures.
• Low operating torque: Reduced torque enables smaller actuators and easier manual operation.
• Bi-directional sealing: Many designs provide tight shut-off in either flow direction.
• Fire-safe construction: Certified fire-safe designs for hydrocarbon and flammable media.
• Blow-out proof stem: Stem design prevents blow-out under internal pressure.
• Anti-static design: Static discharge path between ball, stem and body for hazardous areas.
• Wide range of materials: Carbon steel, stainless steel, duplex, nickel alloys and specialty alloys.
• Versatile end connections: Flanged, welded, hub connections and special pipeline ends.

How a Trunnion Mounted Ball Valve Works

The operating principle of a trunnion mounted ball valve is straightforward yet highly engineered for performance.

The ball contains a through-bore that allows process fluid to flow when aligned with the pipeline. When the operator

or actuator turns the stem 90 degrees, the ball rotates so that the bore is perpendicular to the pipeline, blocking the flow.

The ball itself is rigidly supported by trunnion shafts. The upper trunnion is typically integrated with the stem or connected

to it, while the lower trunnion is supported in the bottom of the valve body. Around the ball, spring-loaded or elastomer-backed

seat rings move slightly under the influence of line pressure, pressing against the ball surface to form a seal.

Because the line pressure pushes the seats, not the ball, sealing force is distributed more evenly. This configuration reduces

seat wear, limits the torque required to rotate the ball and ensures more stable performance under fluctuating pressure and

temperature conditions—critical requirements in energy industry applications.

Trunnion Mounted vs. Floating ball Valves

When specifying ball valves for energy sector service, a common decision is whether to use a trunnion mounted ball valve

or a floating ball valve. Each design has advantages. The table below summarizes the major differences in terms of

application, size, pressure, torque and cost considerations.

Advantages of Trunnion Mounted Ball Valves in the Energy Industry

The trunnion mounted ball valve offers multiple advantages that match the technical and safety demands of the energy industry:

• High-pressure capability: Stable support and seat design make it ideal for high-pressure oil and gas pipelines, compressor stations and high-pressure steam or condensate lines.
• Large-diameter suitability: The trunnion design scales efficiently to very large diameters used in long-distance pipelines and main process headers.
• Low operating torque: Reduced torque allows the use of smaller, more economical actuators, which is significant for automated pipeline valve stations.
• Reduced seat wear: Balanced load distribution between ball, seats and trunnions improves service life, especially under frequent cycling or high differential pressure.
• Reliable sealing at low pressure: Spring-loaded seats ensure tight shut-off even at low line pressures or during depressurization.
• Bi-directional sealing: Many designs seal effectively in both flow directions, simplifying piping design and installation.
• Suitability for buried and subsea service: Robust construction and actuator compatibility support installation in remote and challenging environments.
• Compliance with energy industry standards: Designs can meet API, ISO, ASME and fire-safe testing requirements commonly specified in energy projects.

Typical Energy Industry Applications

Trunnion mounted ball valves are used throughout the energy value chain. The following sections highlight common

applications in upstream, midstream and downstream segments, as well as in power generation and renewable energy projects.

Upstream Oil and Gas

• Wellhead isolation and flowline block valves
• Separator, heater, and treaters inlet and outlet isolation
• Manifold and gathering system block valves
• High-pressure gas injection and water injection lines
• Offshore platform and FPSO process isolation valves

In upstream environments, trunnion mounted ball valves are selected for their ability to handle multiphase flow,

sour service, high pressure and variable process conditions. Materials and seat designs are often customized based

on CO₂, H₂S and sand content.

Midstream Pipelines and Terminals

• Long-distance crude oil and natural gas transmission pipelines
• Pig launcher and receiver station block valves
• Compressor and pump station suction and discharge valves
• Block valves at river crossings, road crossings and critical sections
• Tank farm inlet, outlet and manifold isolation valves

In midstream service, the trunnion mounted ball valve is a standard choice for main-line block valves due to its

tight shut-off, fast quarter-turn operation and compatibility with pipeline pigging requirements. Emergency shutdown (ESD)

and remote operation are common through electric or pneumatic actuators.

Downstream Refining and Petrochemical Plants

• Hydrocarbon feed and product lines
• High-pressure hydrogen and reformer gas lines
• FCC, hydrocracking and hydrotreating unit isolation valves
• Highly flammable or toxic service block valves
• Loading arms and marine terminal transfer lines

Trunnion mounted ball valves in downstream plants must withstand high temperatures, cyclic loading, and exposure

to aggressive chemicals. Fire-safe, anti-static and low-emission designs are critical for meeting plant safety and

environmental standards.

Power Generation

• Fuel gas and fuel oil lines to gas turbines and burners
• High-pressure water, condensate and feedwater systems
• Cooling water and auxiliary systems
• Combined-cycle power plant block valves
• Bypass and interconnection lines in balance-of-plant systems

In power plants, reliability and fast operation are essential. Trunnion mounted ball valves support automated safety

functions, rapid isolation and compatibility with digital control systems via actuators.

Renewable and Low-Carbon Energy

• Hydrogen production, storage and transportation systems
• Biofuel processing plants and terminals
• Carbon capture, utilization and storage (CCUS) pipelines
• Geothermal power plant fluid handling

For emerging renewable and low-carbon energy projects, trunnion mounted ball valves are adapted with suitable materials,

seals and design features to manage new media such as high-purity hydrogen, CO₂ streams and corrosive geothermal brines.

Design Types of Trunnion Mounted Ball Valves

Trunnion mounted ball valves for the energy industry are available in various body constructions, seat configurations and

end connections. The choice depends on pipeline design, maintenance philosophy, pressure class and regulatory requirements.

Body Construction Types

Seat Design Options

• Soft-seated trunnion valves: Use polymeric materials such as PTFE, RPTFE, PEEK or other engineered plastics for excellent tightness at moderate temperatures.
• Metal-seated trunnion valves: Use hard-faced metal seat rings for high-temperature, erosive or abrasive service where soft seats would deteriorate.
• Double block and bleed (DBB): Seats on both sides of the ball can seal simultaneously, allowing venting of the cavity between them.
• Double isolation and bleed (DIB): Seats are designed to seal against pressure from both sides, providing enhanced isolation.

End Connection Types

• Flanged ends: Raised-face (RF), ring-type joint (RTJ) and flat-face flanges in accordance with ASME or other standards.
• Butt-weld ends: For permanent connections in high-pressure pipelines and process lines.
• Socket-weld ends: Applied in smaller sizes and high-pressure services.
• Hub and clamp connections: Used in offshore and specialized high-pressure systems.

Materials for Trunnion Mounted Ball Valves in the Energy Sector

Material selection is critical in energy industry applications due to pressure, temperature, corrosive media and safety requirements.

Typical materials for trunnion mounted ball valves include:

• Carbon steel: Common for general-purpose hydrocarbon service and water service.
• Low-temperature carbon steel: For cryogenic or low-temperature applications such as LNG service.
• Stainless steel: Used in corrosive environments, high-purity service and aggressive chemical processes.
• Duplex and super duplex stainless steel: For seawater, sour service and chloride-containing media.
• Nickel alloys and special alloys: For highly corrosive or high-temperature media including certain acids and sour gas.
• Overlay and hard-facing materials: Such as Stellite, Inconel or tungsten carbide on seats and ball surfaces to resist wear and corrosion.

Typical Technical Specifications

Energy industry specifications for trunnion mounted ball valves typically cover size, pressure class, temperature range, materials,

testing and special design features. The following table provides representative ranges used in many projects.

Actual limits depend on detailed engineering and product design.

Performance Characteristics Important to the Energy Industry

Shut-off and Leakage Performance

Energy pipelines and process units require reliable isolation to prevent product loss, environmental incidents and safety hazards.

Trunnion mounted ball valves are typically designed to provide tight shut-off, often referred to as bubble-tight sealing.

Testing is performed according to standards such as API 6D, API 598 and relevant ISO standards to verify leakage rates.

Torque and Actuation

Because of the support and seat loading design, trunnion mounted ball valves have significantly lower operating torque than

floating ball valves in similar size and pressure classes. This advantage is crucial when:

• Specifying electric actuators with limited torque output.
• Using pneumatic actuators powered by plant instrument air.
• Designing emergency shutdown systems requiring fail-safe positions.
• Reducing actuator size, operating costs and space requirements.

Fire-Safe Design

In hydrocarbon service, fire-safe performance is essential. Fire-safe trunnion mounted ball valves incorporate

metal-to-metal sealing and secondary sealing mechanisms that maintain a degree of tightness after exposure to fire.

Fire testing is conducted according to standards such as API 607, API 6FA or equivalent to confirm that valves

can limit external leakage and seat leakage during and after fire exposure.

Emissions and Fugitive Leakage

Environmental regulations increasingly limit fugitive emissions from valve stems and body joints.

Trunnion mounted ball valves for the energy industry can be designed with low-emission packing,

live-loaded gland systems and welded body joints to meet ISO 15848 or other emission standards.

These low-emission designs reduce volatile organic compound (VOC) releases and help operators comply with

environmental legislation.

Double Block and Bleed (DBB) and Double Isolation and Bleed (DIB)

For critical isolation points in pipelines and process plants, energy industry specifications often require

double block and bleed (DBB) or double isolation and bleed (DIB) capability. Understanding the difference

between DBB and DIB helps in selecting the right trunnion mounted ball valve configuration.

Double Block and Bleed (DBB)

In a DBB trunnion mounted ball valve, seats on both sides of the ball are designed to block fluid from

both upstream and downstream simultaneously when the valve is closed. The cavity between the seats

can be vented or drained through a bleed valve. This allows:

• Verification of seat tightness by monitoring cavity pressure.
• Safe maintenance or removal of downstream equipment without full system depressurization.
• Isolation of sections in pipelines and process units for testing.

Double Isolation and Bleed (DIB)

A DIB trunnion mounted ball valve provides sealing of pressure from both sides of the valve even if one seat fails.

Seats are designed to seal in both directions, often with one upstream and one downstream seat having different

pressure-energized characteristics. DIB is used where:

• Enhanced safety or environmental protection is required.
• Media on each side of the valve must be kept strictly separated.
• Additional protection against seat leakage is mandated by project standards.

Actuation Options for Energy Applications

Trunnion mounted ball valves are typically automated in energy industry facilities. Common actuation options include:

• Manual operation: Lever or gear operators for smaller valves and non-critical locations.
• Pneumatic actuators: Double-acting or spring-return designs powered by air; widely used for on/off and emergency shutdown services.
• Hydraulic actuators: Used in high-torque, subsea and remote applications, or where pneumatic supply pressure is limited.
• Electric actuators: Suitable for process control, modulating duties and areas without pneumatic or hydraulic infrastructure.

Accessories such as limit switches, position transmitters, solenoid valves, local control stations and partial stroke testing devices

are often integrated for safety instrumented systems in the energy sector.

Standards and Certifications

Trunnion mounted ball valves for energy industry applications must comply with relevant design, testing and quality standards.

Commonly referenced standards include:

• Design and Manufacturing: API 6D, API 608, ISO 17292, ASME B16.34.
• Pressure-Temperature Ratings: ASME B16.34, ASME B16.5 (flanged ends).
• End Connections: ASME B16.5 (flanged), ASME B16.25 (butt-welded), ISO or regional pipeline standards.
• Testing: API 598, API 6D testing requirements, ISO test standards.
• Fire-Safe Testing: API 607, API 6FA or ISO 10497.
• Fugitive Emissions: ISO 15848, TA-Luft (where applicable).
• Material Standards: ASTM and equivalent specifications for body, trim and bolting materials.
• Quality Management: ISO 9001 for manufacturing and quality systems.

Installation and Maintenance Considerations

Proper installation and maintenance help maximize the life and performance of trunnion mounted ball valves in the energy industry.

Installation Guidelines

• Verify that the valve pressure class, temperature rating and materials match the system design.
• Install the valve in the correct orientation, especially for designs that are not fully bi-directional.
• Ensure pipeline is clean and free of debris before installation to avoid seat damage.
• Support the pipeline adequately to prevent excessive loads on the valve body and connections.
• Check actuator alignment and stroke limits prior to pressurizing the system.

Maintenance Practices

• Perform regular visual inspections of body joints, packing glands and actuator connections.
• Monitor operating torque and cycle frequency; rising torque may indicate seat or stem packing issues.
• Use cavity relief valves or drain connections to safely depressurize body cavities before maintenance.
• Follow the valve manufacturer’s recommended lubrication and maintenance intervals.
• Document inspection, testing and maintenance activities to comply with energy sector regulations.

Common Challenges and Solutions in Energy Applications

Energy industry environments present several challenges for trunnion mounted ball valves. Key issues and

possible engineering solutions include:

• Erosion and abrasion:

  High-velocity flow with sand or solid particles can erode seats and ball surfaces.

  Metal-seated designs and hard-faced trims can extend service life.

• Corrosion:

  Sour service, seawater exposure and aggressive chemicals can corrode standard materials.

  Corrosion-resistant alloys, duplex steels and appropriate coatings mitigate this risk.

• Temperature extremes:

  Cryogenic LNG service or high-temperature steam requires specialized body and seat materials to maintain tightness.

• Pressure surges:

  Rapid valve operation can cause water hammer or pressure transients.

  Controlled actuation speed and pipeline surge analysis reduce these effects.

• Fugitive emissions:

  Strict regulations demand low leakage from stems and body joints.

  Low-emission packing systems, welded bodies and monitoring help maintain compliance.

Selection Guidelines for Energy Industry Engineers

When selecting a trunnion mounted ball valve for energy industry applications, engineers should systematically evaluate the following:

1. Process conditions: Pressure, temperature, fluid composition, corrosiveness, solids content.
2. Functional requirements: On/off or control duty, required speed of operation, fail-safe position.
3. Safety and regulatory needs: Fire-safe rating, low emissions, DBB or DIB, SIL requirements.
4. Mechanical and piping constraints: Space, weight, end connections, pipeline pigging compatibility.
5. Actuation and control: Availability of pneumatic, hydraulic or electric power, integration with control systems.
6. Lifecycle costs: Initial purchase cost, expected maintenance, downtime impact and service life.

A well-chosen trunnion mounted ball valve can significantly improve reliability, reduce unplanned shutdowns and

enhance overall safety in energy facilities, making the selection process a critical engineering decision.

Frequently Used Terms Related to Trunnion Mounted Ball Valves

Conclusion

Trunnion mounted ball valves play a central role in the energy industry, offering reliable tight shut-off,

low operating torque and long service life under demanding operating conditions. From high-pressure gas pipelines

and offshore platforms to refineries, petrochemical plants and power generation facilities, this valve design

delivers performance, safety and regulatory compliance.

By understanding the key features, design options, materials, standards and application-specific challenges,

energy sector engineers and specifiers can select trunnion mounted ball valves that optimize operational

reliability and minimize lifecycle costs. With appropriate installation, actuation and maintenance practices,

trunnion mounted ball valves provide robust and efficient flow control solutions across the entire energy value chain.