Zhejiang Dongri Valve Co., Ltd.
Designed for 50 years of demanding service, the trunnion Ball Valve is engineered to deliver long-term reliability in critical industrial applications. Its robust construction withstands high pressure, frequent operation, and harsh working conditions, while the trunnion-mounted ball ensures stable performance and reduced operating torque. Advanced sealing technology helps prevent leakage and maintain dependable shutoff over time, minimizing maintenance needs and operational interruptions. From oil and gas to petrochemical, power, and process industries, this durable Valve provides consistent flow control, exceptional sealing performance, and lasting value where safety and reliability matter most.
A trunnion ball valve may spend decades inside a pipeline, refinery, gas processing plant, or power facility. It can face high pressure, temperature changes, vibration, corrosive media, and long periods without operation. After 50 years, the key question is not simply whether the valve still opens and closes.
The real question is whether it still provides reliable isolation, controlled sealing, and safe maintenance access.
I have seen many buyers focus on the valve body and pressure rating. That is only part of the decision. A valve that looks strong from the outside may still have worn seats, damaged stem seals, corrosion in the cavity, or outdated actuator components.
A trunnion ball valve supports the ball with a lower stem, called a trunnion. This design reduces the operating torque created by line pressure. The result is a more stable operation for large-diameter and high-pressure systems. The valve does not rely on the stem alone to carry the ball load.
That structure helps explain why trunnion ball valves remain common in oil and gas pipelines, LNG facilities, chemical plants, and water injection systems.
A long service life starts with the valve body.
Forged steel and cast steel bodies are used for different project needs. Forged bodies are often selected where high mechanical strength and compact construction matter. Cast bodies can support larger sizes and certain project layouts. The choice should match the pressure class, temperature range, fluid, piping loads, and applicable design standard.
Material selection deserves the same attention. Carbon steel may suit many hydrocarbon services, while stainless steel, duplex stainless steel, or corrosion-resistant alloys may be considered for wet gas, seawater, sour service, or chemical media.
I do not treat “corrosion resistant” as a complete answer. The fluid composition, chloride level, hydrogen sulfide exposure, pressure, and temperature all affect the result. A material that performs well in dry gas may face a different risk in wet or sour conditions.
The sealing system also determines how the valve behaves over time.
Many trunnion ball valves use soft seats made from materials such as PTFE, RPTFE, nylon, or PEEK. Metal-seated versions may be selected for abrasive media, high temperature, or severe service. Each seat material has a working range. Choosing a seat only because it has a lower purchase cost can create problems during operation.
Seat leakage may come from solids trapped between the ball and seat, poor cleaning, thermal damage, incorrect material selection, or pressure changes. A well-designed valve can still require inspection and maintenance when the service is demanding.
A double block and bleed arrangement gives operators a way to isolate the line and release pressure from the valve cavity. This feature supports maintenance and leak checking, but it does not remove the need for a proper isolation plan. Operators still need to confirm the valve design, bleed points, drain routing, and site procedures.
Fire-safe design is another common requirement in hydrocarbon service. A fire-safe valve is tested against defined conditions. It does not mean the valve remains unaffected by every fire scenario. The project specification should identify the required test standard and acceptance criteria.
I pay close attention to the stem area because stem leakage can create a serious operating concern. A suitable stem seal system, anti-blowout stem, correct packing arrangement, and regular inspection can help reduce risk. The actuator also needs care. Pneumatic, hydraulic, and electric actuators have different service needs, and the actuator should match the valve torque across the full operating range.
A real maintenance pattern appears across many older pipeline systems: the main body remains usable, while the soft parts, gearbox, actuator seals, position switches, and coating require attention. In some cases, the valve is refurbished instead of replaced. The decision depends on inspection results, spare part availability, pressure testing, material records, and the cost of removing the valve from service.
A practical review can follow this path:
A valve that has been closed for years may not operate smoothly when it is needed. Deposits can harden, lubricants can degrade, and the actuator can lose performance. Periodic operation, where allowed by the process and site safety plan, can reveal problems before an emergency shutdown or maintenance event.
The age of a trunnion ball valve is only one part of its condition. Some valves installed decades ago continue to serve after inspection and refurbishment. Some newer valves require early attention because the fluid, installation, operation, or maintenance practice placed them under heavy stress.
My view is simple: a 50-year service claim should never replace an engineering review. A trunnion ball valve can provide long service when its materials fit the media, its pressure rating matches the system, its sealing parts receive care, and its operating history is understood.
Reliability comes from the complete system: valve design, installation, actuator setup, inspection, spare parts, and the people who maintain it.
A valve installed in a pipeline may need to work for decades. During that time, it can face pressure changes, temperature swings, corrosive media, frequent shutdowns, and long periods without operation. When the valve is hard to operate or fails to seal, the cost can reach far beyond the valve itself.
That is why many pipeline operators choose a trunnion mounted ball valve for large-diameter and high-pressure service. Its design helps control ball movement, reduce operating torque, and support stable shutoff over a long operating period.
A service life of 50 years is not automatic. It depends on the valve design, material selection, installation quality, operating conditions, inspection plan, and maintenance history. The value of a trunnion ball valve comes from how these factors work together.
A floating ball valve uses line pressure to push the ball toward the seat. This design can work well in many applications, though the required operating torque may rise as valve size and pressure increase.
A trunnion ball valve uses a fixed ball supported by a lower stem or trunnion and an upper stem. The ball does not move freely with the line pressure. The seats move toward the ball to create the sealing contact.
This arrangement can offer several practical benefits:
When I evaluate a valve for a long pipeline project, I do not look only at the pressure class or purchase price. I check how the internal parts carry the load, how the seats respond to pressure, and whether the actuator can operate the valve after years of service.
The seats are among the most critical parts of a ball valve. They must seal against the ball while handling pressure, temperature, and the properties of the process medium.
A trunnion ball valve may use a single-piston effect or double-piston effect seat design. The right choice depends on the pipeline specification and safety requirements.
A single-piston effect seat can allow pressure in the valve body cavity to move the seat away from the ball under certain conditions. This can help relieve body cavity pressure.
A double-piston effect seat can maintain sealing when pressure exists from the body cavity side. This feature may support double isolation in selected designs, but it can also require a separate cavity pressure relief system.
The design should match the service. A seat that performs well with clean natural gas may not have the same life in abrasive slurry or a medium containing hard particles. Seat material, elastomer compatibility, temperature range, and pressure direction all require review before selection.
The stem transfers actuator movement to the ball. A properly supported stem reduces stress during operation and helps maintain control of the valve.
Many trunnion ball valves use an anti-blowout stem design. The stem is retained inside the body so that pressure does not force it out if the packing area is damaged. This feature supports safer operation, though it does not replace correct installation and inspection.
Stem sealing also deserves attention. Common sealing arrangements include O-rings, graphite packing, or a combination of sealing elements. The choice depends on temperature, emissions requirements, chemical exposure, and service conditions.
A valve that operates only a few times each year still needs a reliable stem seal. Long idle periods can cause deposits, seal aging, or increased operating torque. A planned inspection can identify these issues before the valve is needed for an emergency shutdown.
A valve may have a strong body, yet still fail early if the trim or seals do not match the medium.
Material selection usually considers:
Carbon steel may be suitable for many pipeline applications. Stainless steel, corrosion-resistant alloys, special coatings, or sour-service materials may be required for harsher conditions.
The ball and stem may use surface treatments or hard coatings to reduce wear. These treatments do not make the valve suitable for every medium. I always compare the coating, base material, seat material, and process conditions as one system.
Consider a buried gas transmission line with a large valve installed at a block valve station. The valve may remain open for long periods and close only during maintenance or an abnormal operating event.
The valve needs low operating torque because the actuator must move the ball after months of inactivity. It also needs reliable sealing when the line is isolated. Moisture protection around the stem and body becomes important because the external environment can damage exposed components over time.
In this case, the operator may focus on:
A similar valve in a refinery may face more frequent cycling and higher temperature. A valve used in water service may face different corrosion and scaling risks. The same trunnion ball valve design cannot be copied across every application without a service review.
A well-made valve can still develop problems if it is installed poorly.
The pipeline should be cleaned before the valve is put into service. Welding debris, sand, rust, and other particles can damage the seat or scratch the ball surface. The valve should remain in the correct open or closed position during line flushing, based on the manufacturer’s instructions.
Other installation points include:
Pipe stress can transfer loads to the valve body. Those loads may not cause an immediate leak, yet they can affect operation over time. Proper alignment and support help reduce this risk.
A 50-year operating target requires a maintenance plan. The plan does not need to mean frequent disassembly. It should match the valve’s duty and risk level.
Routine checks may include:
Sealant injection can help restore sealing in some situations, but it should not be used to hide a damaged seat or ball. Repeated injection without fault analysis may make future maintenance more difficult.
The maintenance record should show when the valve was operated, what torque was measured, whether leakage was found, and which parts were replaced. This information helps the operator see changes before they become a larger problem.
Several conditions can reduce service life:
The phrase “50 years” should be treated as a service goal, not a blanket promise. A valve in clean, stable service with proper maintenance may operate for many decades. A valve exposed to erosion, severe corrosion, or frequent cycling may need major repair much earlier.
When I help a customer select a trunnion ball valve, I ask for more than size and pressure class. I need to understand the complete operating picture:
The answers guide the choice of body material, seat system, stem seal, actuator, coating, testing, and accessories.
A lower purchase price may look attractive, yet the full cost includes installation, actuator sizing, inspection, repairs, downtime, and replacement. A valve with a suitable design and a clear maintenance plan can offer better value across its working life.
A trunnion ball valve stands strong through more than its metal body. Its long-term performance comes from load support, seat design, compatible materials, correct installation, and regular checks. When these elements match the pipeline service, the valve can remain dependable for decades and support safer, more predictable plant operation.
When a pipeline carries gas, oil, or other process media under pressure, valve selection affects more than flow control. The valve must handle pressure changes, repeated operation, limited maintenance access, and the safety needs of the site.
This is where a trunnion-mounted ball valve can be a practical choice. Its design supports the ball from both the top and bottom, helping reduce the operating load placed on the valve stem and seats.
I look at trunnion ball valves through four questions:
The answers help determine whether this valve design fits the system.
A floating ball valve uses line pressure to push the ball against the downstream seat. That design can work well for smaller sizes and moderate pressure service. As valve size and pressure increase, the ball becomes heavier and the force on the seats can rise.
A trunnion ball valve uses a fixed ball supported by a lower trunnion and a stem. The ball does not move freely with the flow pressure. The seats move toward the ball, which can reduce friction during operation.
This structure may provide several practical benefits.
Lower operating torque
Large valves can require high torque when the ball presses against the seats. A trunnion design supports the ball and reduces the force needed to rotate it. That can allow the use of a smaller actuator, depending on the pressure, temperature, media, and valve configuration.
Lower torque also helps reduce stress on the stem, gearbox, and actuator connection. For an automated pipeline valve, this can support smoother opening and closing.
Suitable for larger valve sizes
Trunnion ball valves are often selected for large-diameter pipelines, storage systems, gas processing units, and industrial plants. A 24-inch valve on a gas transmission line has a different mechanical demand from a small utility valve. The ball weight, pressure load, and actuator size all become more important as the valve grows.
The fixed-ball structure gives engineers a way to manage these loads without relying on the downstream seat alone.
Bidirectional shutoff
Many trunnion ball valves use a double-piston seat design. Pressure from the body cavity or the pipeline can push the seats toward the ball. This may provide shutoff from either flow direction when the valve is designed and tested for that service.
The actual performance depends on seat material, pressure rating, temperature, media, and testing standards. A buyer should review the valve data sheet instead of relying only on general product descriptions.
Reduced seat wear
The ball rotates with limited contact against the seats during normal operation. Reduced rubbing can help lower seat wear, especially during repeated cycles.
A valve used for isolation may operate only a few times each year. A valve used in process control or pressure management may cycle much more often. The right seat material and actuator setup still matter. A trunnion design does not remove the need for correct sizing, clean installation, and planned inspection.
Support for emergency shutdown systems
Pipeline and process plants often use ball valves as isolation or emergency shutdown devices. A spring-return actuator can move the valve to a safe position when air, hydraulic power, or electrical control is lost.
The valve package may include a fire-safe design, cavity relief, stem sealing, position feedback, and an emergency shutdown actuator. Each feature should match the site standard and project specification. These parts should be reviewed as one system rather than selected separately.
Consider a natural gas transmission station with a large-diameter isolation valve. The valve may stay open for long periods and close during maintenance, pressure events, or an emergency signal. A trunnion ball valve can suit this duty because the supported ball helps manage operating torque, while the actuator provides controlled movement.
A different example is a tank farm handling hydrocarbon liquids. The valve may need tight isolation during transfer line maintenance. Here, the buyer may focus on seat compatibility, fire-safe testing, fugitive emission control, and cavity pressure relief. The trunnion structure is useful, but it is only one part of the selection.
Before choosing a valve, I recommend checking these points:
Maintenance teams should also confirm whether the valve allows seat inspection, seal replacement, or online cavity monitoring. A valve with a suitable design can still create problems if spare parts are hard to obtain or the installation leaves no safe working space.
My view is simple: a trunnion ball valve is most useful when the system involves larger sizes, higher pressure, frequent automation, or a strong need for dependable isolation. It may not be the best fit for every line. Smaller services, low-pressure systems, or simple utility applications may call for a different valve design.
Good valve selection starts with the service conditions, not with a product name. When pressure, temperature, media, cycle rate, actuator needs, and maintenance plans are reviewed together, the trunnion ball valve can offer a strong balance of mechanical support, controlled operation, and shutoff performance.
When I choose a ball valve for a high-pressure line, I look beyond the simple open-and-close function. The valve must manage pressure, reduce operating effort, support safe isolation, and remain serviceable after long periods in demanding conditions.
That is where a trunnion ball valve can fit well.
Its design has been used across oil and gas, chemical processing, power generation, water treatment, and other process industries for many years. The right choice still depends on pressure rating, fluid type, temperature, pipe size, actuation method, and maintenance needs.
A trunnion ball valve uses a fixed ball supported by upper and lower stems, known as trunnions. The ball does not carry the full weight of the operating force through the seats.
When the actuator turns the ball, the flow passage moves into line with the pipe. A quarter-turn moves the valve from open to closed. The fixed-ball design helps reduce the torque needed to operate larger valves or valves exposed to higher line pressure.
The seats press against the ball to create a seal. Depending on the design, the valve may use soft seats, metal seats, or a combination selected for the process conditions.
This structure gives the valve a practical role in pipelines where a floating ball design may require more operating force as size and pressure increase.
I usually see four main reasons behind the selection of a trunnion ball valve.
Lower operating torque
A large ball valve can be difficult to operate when line pressure rises. The trunnion supports the ball and reduces the load placed on the seats. The actuator may need less torque, which can affect the size and cost of the actuation system.
Support for larger pipe sizes
As pipe diameter increases, the ball becomes heavier and the pressure load grows. The trunnion structure provides mechanical support for the ball, making this design suitable for many large-bore pipeline applications.
Reliable shutoff when correctly specified
A trunnion ball valve can provide tight shutoff when the body, seats, stem, and sealing system match the fluid and operating conditions. Seat design matters. A valve made for clean gas may not be suitable for abrasive slurry or fluid containing solid particles.
Options for pressure relief
Some trunnion ball valves use a double-piston effect or another seat design that helps manage pressure trapped inside the body cavity. The exact function depends on the manufacturer’s design and test data, so I check the product documentation rather than assuming every valve works the same way.
I use a clear set of questions before choosing a valve.
1. Identify the medium
Record the fluid, concentration, particle content, corrosive behavior, and viscosity. Natural gas, steam, crude oil, chemical fluid, and wastewater place different demands on seat and seal materials.
2. Confirm pressure and temperature
Check normal pressure, maximum pressure, minimum and maximum temperature, and possible pressure surges. A valve rating should match the system conditions, not only the usual operating point.
3. Select the body and seat materials
Carbon steel, stainless steel, alloy steel, PTFE, reinforced polymers, and metal seat materials each have specific uses. Material compatibility affects service life and leakage control.
4. Review the end connection
Flanged, welded, threaded, and other connection types serve different installation needs. For a pipeline that should reduce potential leak points, a welded connection may be considered. Maintenance access and local installation practice still need to be reviewed.
5. Match the actuator
Manual gear operation may suit smaller or less frequent applications. Pneumatic, electric, or hydraulic actuators can support remote operation and automated shutdown. The actuator must provide enough torque for the full pressure and temperature range.
6. Check testing and documentation
I ask for pressure test records, material certificates, seat leakage information, dimensional drawings, operating instructions, and maintenance guidance. These documents help the installation team confirm that the supplied valve matches the purchase specification.
Imagine a gas processing facility with a large pipeline isolation valve. The valve operates only during maintenance shutdowns, yet it must remain ready for service after long periods without movement.
The maintenance team may inspect the actuator, check stem seals, review external corrosion, confirm position indication, and operate the valve according to the site procedure. If the valve remains difficult to operate, the team should not force the handwheel or actuator. They need to check for pressure imbalance, actuator problems, stem damage, deposits, or a seat issue.
This example shows why valve selection and maintenance work together. A suitable valve can still face problems when the wrong actuator is installed, the line contains unexpected solids, or inspection records are incomplete.
A low purchase price does not show the full cost of a valve. A mismatch between seat material and process fluid can create leakage or early replacement. An actuator with insufficient torque can prevent full operation. Incorrect face-to-face dimensions can delay installation.
I also avoid treating “trunnion ball valve” as a complete specification. The term describes the support design, not every detail of the product. Pressure class, bore size, body material, seat construction, stem sealing, fire-safe design, emission control, and testing requirements must be stated separately.
A good purchase specification gives the supplier enough information to recommend a suitable configuration. It also gives the buyer a clear way to compare different offers.
For high-pressure and large-diameter isolation service, a trunnion ball valve can offer useful mechanical support, controlled operating torque, and several seat and actuator options. Its performance depends on correct sizing, compatible materials, proper testing, and regular inspection.
I treat the valve as part of the whole piping system, not as an isolated component. That approach helps reduce selection errors and supports safer, more predictable operation over the service life of the equipment.
Want to learn more? Feel free to contact Wang Zhixiang: 241126365@qq.com/WhatsApp +8613777730323.
American Petroleum Institute — 2019 — Specification for Pipeline and Piping Valves API Specification 6D
International Organization for Standardization — 2021 — Petroleum and Natural Gas Industries Pipeline Transportation Systems Pipeline Valves ISO 14313
American Society of Mechanical Engineers — 2022 — Valves Flanged Threaded and Welding End ASME B16.34
American Petroleum Institute — 2022 — Fire Test for Quarter-Turn Valves and Valves Equipped with Nonmetallic Seats API Standard 607
American Petroleum Institute — 2018 — Fire Test for Valves with Quarter-Turn and Actuator API Specification 6FA
International Organization for Standardization — 2016 — Industrial Valves Measurement Test and Qualification Procedures for Fugitive Emissions ISO 15848-1
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November 02, 2026
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