In today’s industrial landscape, the safe and efficient transport of fluids and gases is critical to countless operations — from oil and gas pipelines crossing thousands of miles to complex chemical processing systems and high-pressure steam networks. One of the most trusted flow control solutions in these demanding environments is the trunnion mounted ball valve, particularly when engineered from forged steel.
While the “floating ball valve” is widely recognized as the industry standard for general-purpose flow shutoff, the trunnion-mounted design represents a significant leap forward in ball valve technology. This design ensures robust sealing, reliable operation under extreme pressure conditions, and excellent cost-effectiveness for large-diameter and high-pressure pipelines. When forged steel is used in the construction, these benefits are further amplified — offering unmatched strength, resilience, and longevity.
At its core, a ball valve is a quarter-turn valve that controls the flow of a medium — whether liquid or gas — by rotating a spherical disc (the “ball”) with a bore through its center. In a floating ball valve, the ball is held in place only by the seats and is free to move slightly along the axis of the pipeline, which helps create a tight seal against the downstream seat when pressure is applied.
In contrast, a trunnion mounted ball valve uses mechanical anchoring at both ends of the ball. One end of the ball is connected to the valve stem, while the other end is supported by a trunnion — a type of shaft or pivot that absorbs the axial loads generated by the upstream pressure. This design improvement stabilizes the ball, reduces the torque required to operate the valve, and enables the use of larger diameters and higher pressure classes without compromising performance.
The trunnion design’s key advantage lies in its ability to handle both low- and high-pressure systems with remarkable reliability and efficiency. The seat rings in a trunnion valve are typically spring-loaded, ensuring that they maintain constant contact with the ball to achieve a tight seal, even in low-pressure scenarios where fluid force alone would be insufficient.
For operators, this means:
The trunnion absorbs the downstream forces, minimizing stress on the valve seats and the stem. This feature makes trunnion valves the preferred choice for pipelines transporting crude oil, natural gas, liquefied natural gas (LNG), and other high-value or hazardous fluids.
By absorbing excess pressure, the trunnion significantly reduces the torque required to rotate the ball. As a result, smaller and more cost-effective actuators can be used, which translates into lower installation and maintenance costs.
Because the mechanical design ensures more uniform sealing and load distribution, wear and tear on the valve seats are minimized, resulting in a longer service life and reduced risk of leaks or blowouts.
While the trunnion-mounted design offers clear mechanical advantages, material selection plays an equally vital role. Forged steel stands out as the premium choice for trunnion ball valves, especially for high-pressure, high-temperature, or corrosive service conditions. Here’s why:
Forging subjects the steel to intense pressure and thermal processes that align and refine its grain structure. This creates a denser, more uniform material with superior mechanical properties compared to cast steel or standard rolled steel. As a result, forged steel valves can withstand higher pressures and resist cracking or deformation under stress.
Forged steel maintains its integrity across a wide range of temperatures — from sub-zero arctic conditions in gas pipelines to the high heat of steam or process fluids in refineries and power plants.
Many forged steel alloys are designed to resist corrosion from water, chemicals, and hydrocarbons, which means less maintenance and downtime due to corrosion-related failures.
Forged components exhibit greater toughness than cast parts, meaning they can absorb sudden impact or pressure surges without catastrophic failure.
Unlike casting, forging minimizes the risk of internal voids, inclusions, or porosity. This ensures more reliable performance under demanding service conditions.
A forged steel trunnion mounted ball valve typically incorporates several advanced design elements that maximize safety, durability, and ease of use:
Trunnion ball valves are equipped with spring-loaded seat rings that maintain contact with the ball even under fluctuating pressures. This ensures tight shutoff whether the system is operating at full capacity or is depressurized. In emergency shutoff scenarios, this can be the difference between a contained incident and a major leak.
Many trunnion valves offer a Double Block and Bleed configuration, allowing operators to block flow from both upstream and downstream sides while bleeding off pressure trapped in the cavity. This feature enhances safety during maintenance and testing by ensuring complete isolation.
For additional safety, trunnion valves include an anti-blowout stem design that prevents the stem from being ejected from the valve body under extreme internal pressure — a critical feature for high-pressure or hazardous media applications.
Some designs feature emergency sealant injection systems for both seats and stem areas. In the event of minor seat damage or leakage, operators can inject a sealant to restore tight shutoff until permanent repairs can be made.
When specified, forged steel trunnion ball valves can be engineered with fire-safe seals and anti-static devices to meet stringent industry safety standards such as API 607 and ISO 10497. This ensures that, even in the event of a fire, the valve maintains its sealing function and prevents sparks due to static build-up.
Forged steel trunnion mounted ball valves are the backbone of many industrial systems that transport high-pressure or hazardous media. They are particularly vital in:
From upstream extraction sites to midstream transport pipelines and downstream refineries, these valves handle crude oil, natural gas, LNG, and refined products with unwavering reliability.
In processes that involve aggressive chemicals, high pressures, and fluctuating temperatures, the robust construction of forged trunnion valves ensures safe flow isolation.
Power plants rely on these valves to manage steam, feedwater, and cooling systems where high pressure and thermal cycling demand durable and dependable shutoff solutions.
Harsh marine environments require corrosion-resistant forged steel valves capable of withstanding both pressure and saltwater exposure.
Heavy-duty forged steel construction stands up to abrasive slurries and corrosive tailings, minimizing downtime and maintenance.
With the right materials and sealing systems, trunnion valves can be adapted for cryogenic service, ensuring tight shutoff for LNG and other low-temperature fluids.
A question that often arises is: Why choose forged steel over cast steel? Both have their place, but for mission-critical applications, the benefits of forging are clear:
Forging aligns the grain flow of the steel to follow the valve’s shape, giving the component higher strength and fatigue resistance.
Castings can develop porosity, shrinkage cavities, or inclusions. Forged parts have fewer of these potential weak points.
Forged steel valves are better suited to absorb vibration and pressure spikes without fracturing.
While cast steel valves may be more economical for less demanding applications, forged steel is the gold standard for performance, safety, and longevity when failure is simply not an option.
One of the major benefits of a trunnion-mounted design is the reduction in operational torque. By anchoring the ball and distributing axial forces to the trunnion and stem, the valve requires less effort to open or close. This means that smaller, more efficient actuators can be used — whether electric, pneumatic, or hydraulic — reducing both capital expenditure and ongoing energy consumption.
For operators managing long pipelines or remote installations, this efficiency translates into tangible savings over the life cycle of the valve.
Manufacturers of forged steel trunnion mounted ball valves adhere to rigorous international standards, such as:
API 6D: Specification for pipeline valves, including design, testing, and inspection.
API 607 / ISO 10497: Fire-safe testing.
ASME B16.34: Valve pressure-temperature ratings and materials.
NACE MR0175 / ISO 15156: Compliance for sour gas service.
PED / CE Marking: For European installations.
By ensuring strict compliance with these standards, end users gain peace of mind that the valve will perform safely and reliably throughout its service life.
Whether you’re transporting millions of barrels of crude oil across continents, refining chemicals under extreme conditions, or managing steam systems in a high-capacity power plant, a forged steel trunnion mounted ball valve is a smart investment. It combines the robust mechanical advantage of the trunnion design with the unmatched strength and resilience of forged steel to deliver safe, reliable flow control — year after year.
In an era where downtime is costly, safety is paramount, and sustainability is non-negotiable, choosing the right valve partner makes all the difference. Our team is committed to engineering valves that meet and exceed industry standards, tailored to your unique operating conditions.
Ready to specify the next generation of pipeline isolation? Contact us today to learn more about our forged steel trunnion mounted ball valves and how we can help you achieve safer, more efficient operations — wherever your pipelines run.
