Trunnion Ball Valve
Trunnion Ball Valve
※ Size Range: 2″-48″
※ Class Range: 150LB-2500LB
※ Fire Safe Design
※ Anti Static
※ Anti blow-out
※ Trunnion Ball Valve Manufacturer
Over the years, the oil and natural gas industry worldwide has been continuously looking to upgrade its system and components, owing to the numerous fatal accidents and incidents that have taken place. Trunnion ball valve is one such component that has been widely accepted in the industry due to its enhanced safety features.
Shut off and control operations along with tight and reliable sealing is one of the most critical requirements in any pipeline system, and when it comes to petrochemicals and hazardous products, it becomes even more important. As a result, trunnion ball valve manufacturers have adopted several safety measures to ensure that their products provide a smooth and reliable operation for the entire lifespan.
So, in this article, we have tried to share the basics of trunnion ball valve. We shall discuss in detail the construction and working of trunnion ball valves, types, advantages, limitations, and a wide range of applications.
What Is A Trunnion Ball Valve?
Trunnion ball valves are one of the several types of ball valves used to stop or start the flow of media in a pipeline system by only a quarter-turn operation. This valve is a solution to the problem of excessive torque required by a floating type of valve in a high-pressure service.
Trunnion ball valve is designed so that it requires a lower operating torque. The valve design provides adequate support for the ball in a shape similar to a shaft which is called a trunnion. As the torque is lowered, the actuator’s size and the valve’s overall cost also decrease.
According to trunnion ball valve manufacturers, these valves are suitable for both low and high-pressure applications and have lower operational costs in comparison to other types of ball valves. In addition, the spring-loaded seat in the valve design helps create effective sealing even in low or no pressure environments.
Construction Of Trunnion Ball Valve
A trunnion ball valve is similar to a traditional ball valve which is primarily comprised of a valve body, valve seat, rotary ball, valve stem, and an operating handle (manual or automatic). However, trunnion valve manufacturers have made some design changes to overcome the difficulties faced in the parent design.
Let us have a look at some of the important components of this valve.
- Valve Body: The valve body or the casing secures and provides support to the interior of the ball valve. The valve body material may differ depending upon the application or media where the valve is used.
- Ball: The sphere-shaped ball is basically the valve disk that rotates to start or stop fluid flow in the pipeline system. The ball has a hole bored through the center to provide an opening to the flowing media. It is connected at one end to the trunnion, and the other is connected to the valve stem.
- Valve Seat: The seat of the trunnion ball valve surrounds and guards the ball inside the valve body. When the actuator turns the valve handle at an angle of 90°, the ball disk is placed tightly against the valve seat, blocking the access of fluid media.
- Trunnion: This is the design feature incorporated in the parent model of the ball valve by trunnion valve manufacturers, wherein additional support is provided from beneath the ball. Trunnion is basically a small extension of the ball similar to a shaft that keeps the ball firmly in place and helps to reduce the operating torque.
- Stem: The stem of the trunnion ball valve is a shaft connected at the top of the ball disk at one end, and the other end is connected to an actuator which can be operated manually or automatically to regulate the movement of the ball valve. The valve stem is strengthened for anti-blowout stems so that they can handle pressurized and intense temperatures without causing any damage.
- Injection Fittings: This is a design feature incorporated by some trunnion valve manufacturers in the seating and stem area for emergency purposes. If the sealing is damaged or weakened, the injection fitting may be used to inject grease, which acts as a partial sealant to stop further leakage.
Trunnion Ball Valve: Working
The trunnion ball valve uses a hollow, perforated, and fixed/supported ball to control fluid flow through it. The trunnion supports the ball at the lower end, and the ball is only allowed to rotate while the significant load is taken care of by the trunnion and its bearings.
The line pressure presses the upstream seat onto the stationary ball, forcing it to provide adequate sealing. The mechanical anchoring of the ball, better known as the trunnion, absorbs the thrust from the line pressure.
This prevents the excess friction between the ball and seats, so the operating torque remains low even at full rated working pressure. In addition, due to such valve design, the size of the actuator is reduced, and hence the overall cost of the trunnion ball valve reduces.
Classification Of Ball Valve
Trunnion Ball valves can be classified according to their body configuration, bore profile, sealing material, body structure, etc.
Classification as per body configuration
- Top entry trunnion ball valve
- Side entry trunnion ball valve
- Welded body trunnion ball valve
Classification as per bore profile
- Reduced bore trunnion ball valve
- Full bore trunnion ball valve
Classification as per sealing material
- Soft seat trunnion ball valve
- Metal seat trunnion ball valve
Classification as per body structure
- Two-piece split ball
- Three-piece split ball
Classification as per body material
- Forged ball trunnion ball valve
- Casting ball trunnion ball vlave
Trunnion Ball Valve: Technical Specifications
- Size Range : DN 50 – DN 1400
- Class Standard : API 6D or API 608
- Design Standard : ASME B16.5, ASME B16.34 and ASME B16.10
- Fire Standard : API 607
- End Connection : Flanged; BW; Threaded
- Operation : Manual Lever / Pneumatic / Electrical
- Valve Body Material : F304L, A105, A182 F304, F316, F51, F316L, F53, A350 LF2, LF3, Inconel, Monel, Hastelloy (Forging), A351 CF3, A351 CF8, A216 WCB, A351 CF3M, A351 CF8M, A890 4A/ 5A, A352 LCC/ LCB (Casting)
- Ball Material : CS+ENP, F304L, F316, A182 F304, F316L, F51, CS+TCC, CS+Ni60, F53
- Seat Material: PTFE, RPTFE, PCTFE, Nylon6, Devlon, PEEK, PPL, TFM, Metal (typically stellite)
- Seat Retainer Material: A182 F304, CS+ENP, F304L, F316, F51, F53, F316L, CS+Ni55, CS+TCC.
- Stem Material : A182 F51, A182 F6a, A182 F316, 17-4PH,
- Packing : RPTFE, Graphite, PTFE
- O-Ring : NBR Buna-N, HNBR, Viton, EPMD, FVMQ, Fluorosilcione
Trunnion Ball Valve: Special Features
Trunnion ball valve manufacturers have adopted various design features to enhance the working and safety standards of these valves to suit the industry’s requirements. Let us discuss some unique features of the trunnion ball valve, which makes it different from other ball valves.
- Emergency Sealant Injection: Some trunnion ball valve design has an injection fitting for the seating and stem area, which is kept for emergency purposes. This is used in the case of a sealing failure to inject temporary emergency sealants.
- Antic Static Device: Anti-static devices establish electrical continuity between the ball, stem, and body, preventing static electrical charges from causing sparks inside the valve.
- Blowout Proof Stem: The stem and body of the trunnion valve are connected to prevent the stem from getting blown out under line pressure.
- Fire-Safe Design: Most trunnion ball valve manufacturers design their products for fire resistance, reducing fire spread and pollution. The valve must comply with API 607 standards.
- Drain Ports: Any fluid retained in the body cavity of a closed valve is released via drain holes at the bottom of the valve.
- Vent Ports: Any gas trapped in the body cavity of a completely closed valve is expelled via vent holes situated at the top of the body cavity.
- Double Block and Bleed: Even when the valve is completely closed, this safety feature incorporated by trunnion valve manufacturers prevents pressure buildup caused by high-pressure media trapped in the valve’s body cavity.
- Coil Springs: This is used in some valve designs for consistent seat loading, which lowers the operating torque.
Advantages of Trunnion Ball Valve
Trunnion ball valve is one of the most commonly used ball valves in industrial application due to its additional advantages over traditional ball valves. Some of them include
- Requires less operating torque. So, reduced actuator size.
- Suitable for both low and high-pressure applications.
- Less friction during valve operation helps mitigate wear and tear. Hence, longer life.
- Full-proof sealing. Therefore fireproof.
Disadvantages of Trunnion Ball Valve
There are certain limitations to the use of trunnion ball valve, which includes
- A trunnion ball valve cannot be repaired in line due to its entirely welded or bolted construction. Repairs would thus disrupt routine pipeline operations.
- If essential maintenance is not performed, welded components may become less efficient due to increased friction.
Applications Of Trunnion Ball Valve
Trunnion ball valves are popular because they may be customized for a broad range of applications. Some of the most common applications include
Oil and Gas Industry
- Because they are leakproof and can handle high pressures.
- Examples: Field gas plants, oil refinery feedstock lines, gas feed. lines, crude oil plants, and industrial gas processing plants.
- Because they offer safe and durable sealing.
- Offer high-temperature resilience.
- Because they can keep up with the large-scale, high temperatures, and high-pressure operations.
- Examples: Geothermal and hydropower plants.
- Because they can handle several different media such as gasses, slurries, and liquids.
- Examples: Cooling & feedwater systems, hydrocarbon processing,
steam service, tank farms, polymers, etc.
As discussed in the article, trunnion ball valves come under a specialized valve category with a wide range of applications, especially in industrial applications like petrochemicals. Due to its critical applications, Trunnion ball valve manufacturers focus on high safety standards, reduced operating torque, longer life span, and lower maintenance costs.
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