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Home News A105 Trunnion Mounted Ball Valve Design: Structure, Working Principle And Advantages
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Introduction

The A105 Trunnion Mounted Ball Valve is widely used in high-pressure oil and gas, petrochemical, natural gas, and industrial pipeline systems. Combining ASTM A105 forged carbon steel with a trunnion-mounted ball structure, this valve provides reliable shut-off, stable operation, and relatively low operating torque.

J-VALVES provides customized trunnion mounted ball valve solutions with professional machining, material control, sealing technology, and pressure testing.

1. A105 Trunnion Mounted Ball Valve Structure

The main components include the valve body, trunnion-mounted ball, stem, seats, sealing system, and operating mechanism.

Unlike a floating ball valve, the ball is mechanically supported by upper and lower trunnions. This structure helps reduce ball movement under pressure and provides stable positioning during operation.

Key structural features include:

  • Forged A105 carbon steel body

  • Trunnion-supported ball

  • Precision-machined stem

  • Replaceable or application-specific seats

  • Reliable stem sealing system

  • Manual or automated operation

2. Working Principle

The A105 Trunnion Mounted Ball Valve operates through a 90-degree rotation.

When fully open, the ball bore aligns with the pipeline, allowing the medium to flow through the valve. When the stem rotates the ball to the closed position, the solid section of the ball blocks the flow passage and the seats provide sealing.

The trunnion support carries part of the mechanical load, helping reduce operating torque. This makes the design particularly suitable for larger valve sizes and higher-pressure applications.

3. Engineering Advantages

Lower Operating Torque

The trunnion-supported ball remains stable during operation, reducing the force required to rotate the ball.

Suitable for Large Sizes

The mechanical support provided by the trunnions makes this configuration suitable for larger pipeline valves.

Reliable Sealing

The ball and seat are precision-machined to provide consistent contact and dependable isolation.

Flexible Actuation

Lower operating torque allows the valve to be equipped with manual gearboxes, pneumatic actuators, or electric actuators.

4. A105 Material Advantages

A105 forged carbon steel provides good mechanical strength and is commonly used for pressure-containing components in industrial piping.

It is suitable for many applications involving:

  • Oil and gas

  • Natural gas

  • Petrochemical fluids

  • Industrial process media

  • High-pressure pipelines

Material selection should always be based on actual pressure, temperature, fluid composition, and project requirements.

5. J-VALVES Manufacturing Advantages

J-VALVES focuses on precision manufacturing and application-specific valve engineering.

Precision Machining: Accurate machining of the ball, stem, seats, and trunnions helps maintain proper alignment and operating performance.

Material Control: A105 material and other selected materials can be verified according to applicable specifications.

Customized Design: Valve size, pressure class, full or reduced bore, connection type, seat material, and actuator configuration can be customized.

Quality Testing: Dimensional inspection, pressure testing, and sealing checks help verify the integrity and performance of finished valves.

6. Typical Applications

A105 trunnion mounted ball valves are commonly used in:

  • Oil and gas pipelines

  • Natural gas transmission

  • Refineries

  • Petrochemical plants

  • Gas processing facilities

  • Pipeline terminals

  • Industrial process systems

Conclusion

The A105 Trunnion Mounted Ball Valve combines the strength of forged carbon steel with the stable and low-torque characteristics of a trunnion-mounted ball design. Its reliable sealing, robust construction, and suitability for larger sizes make it an effective solution for demanding pipeline applications.

With precision manufacturing, customized configurations, material control, and strict quality inspection, J-VALVES provides A105 trunnion mounted ball valve solutions designed for reliable performance in oil and gas, petrochemical, natural gas, and industrial pipeline systems.

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Top entry trunnion mounted ball valve with a one piece body that removes the bolted body joint from the pressure boundary. Seats and seals are serviced through the top cover without cutting the valve out of the pipeline. Nominal Size: 1 inch to 36 inch Pressure Class: ASME Class 150 to 2500 Body Material: WCB, LCC, CF8M, CF3M, A105 forged Body Style: One piece top entry Ball & Stem: CF8M or F316 with ENP coating Seat Material: PTFE, RPTFE, PEEK or metal End Connection: Flanged RF / RTJ, butt weld Operation: Gear, pneumatic or electric actuator Maintenance: In line, through the top cover Design Standard: API 6D / ISO 14313 Test Standard: API 598, API 607 fire safe Options: Sealant injection, cavity relief, extended stem
A high pressure trunnion mounted ball valve for Class 900 to 2500 service, built to API 6D PSL3 with a forged or cast body, spring loaded seats, double block and bleed and sealant injection ports. Suited to wellheads, gas gathering and high pressure process isolation.   Nominal Size: 2 inch to 24 inch (DN50 to DN600) Pressure Class: ASME Class 900 / 1500 / 2500 Body Material: A105 forged, WCB cast, A182 F316, F51 duplex Ball & Stem: A182 F316 with ENP or hard chrome Seat Material: PTFE, RPTFE, PEEK or metal to metal End Connection: Flanged RF / RTJ, butt weld, hub Operation: Gear, pneumatic or electric actuator Design Standard: API 6D / ISO 14313, ASME B16.34 Test Standard: API 598, shell 1.5x and seat 1.1x Fire Safe: API 607 / API 6FA Material Certificate: EN 10204 3.1 with heat number traceability Temperature Range: -29 C to +200 C, trim dependent
Nominal Size :3/4"~60" (DN20~DN1500) Pressure Class :150LB~2500LB (PN10~PN420) Temperature Range: -20℃ ~ +200℃ Body Material :C95800 Nickel Aluminum Bronze Ball Material :C95800 Nickel Aluminum Bronze Stem Material :C95800 Nickel Aluminum Bronze Seat Material :PTFE, RPTFE, PEEK End Connection :Flanged RF Operation: Manual (Lever / Gear), Pneumatic, Electric Design Standard: ASME B16.34, API 608 Test Standard: API 598, ISO 5208 Face to Face: ASME B16.10 Fire Safe Standard: API 607
Nominal Diameter: 0.5" (DN15) Pressure Class: Class 300 (PN50) Temperature Range: -29℃ to +425℃ Body / Bonnet: ASTM A216 WCB cast carbon steel Ball: A105N / WCB with hard chrome plating, or 304 / 316 stainless steel (optional) Stem: 410 / 420 stainless steel or 17-4PH precipitation hardening stainless steel Seat: PTFE, RPTFE, PPL (reinforced PTFE) Sealing Materials: PTFE / RPTFE / PPL (seat), flexible graphite or PTFE (stem packing) End Connection: Flanged (RF Raised Face, conforming to ASME B16.5) Operation: Lever (90° open/close, with optional locking hole) Design Standards: ASME B16.34, API 608 Inspection & Test Standard: API 598 Face-to-Face Dimension: In accordance with ASME B16.10