By: Oswal Industries

The Ultimate Guide to Trunnion Mounted Ball Valves: High-Pressure Flow Control Explained

The Ultimate Guide to Trunnion Mounted Ball Valves: High-Pressure Flow Control Explained

In large-scale industrial operations, controlling the flow of high-pressure fluids and gases requires valves that offer absolute reliability, minimal operating torque, and an unyielding seal. While standard floating ball valves are excellent for smaller, lower-pressure pipelines, they can become difficult to operate or prone to premature wear when scaled up.

This is where the Trunnion Mounted Ball Valve (TMBV) comes into play. Engineered specifically for severe-service, large-diameter, and high-pressure applications, the trunnion design is the unsung hero of global pipeline infrastructure.

In this comprehensive blog, we provide a complete overview of Trunnion Mounted Ball Valves, including how they work, their types, industrial uses, specifications, and materials of construction.

1. Overview: What is a Trunnion Mounted Ball Valve?

To understand a trunnion mounted valve, it helps to contrast it with a traditional floating ball valve:

  • In a floating ball valve, the ball is suspended by the stem and pressed against the downstream seat by the pressure of the fluid.
  • In a trunnion mounted ball valve, the ball is mechanically anchored at both the top and bottom by a shaft or stub (the "trunnion").

Because the ball is fixed in place, the fluid pressure does not push the ball against the seats. Instead, the line pressure forces the upstream seat against the ball to create a bubble-tight seal.

The major benefit? This design drastically reduces the operating torque because the ball doesn't rub heavily against the seats under pressure. This means smaller, less expensive actuators can be used, and the valve experiences significantly less mechanical wear, ensuring a much longer service life.

2. Types of Trunnion Mounted Ball Valves

Trunnion ball valves are highly versatile and come in several structural designs to suit different pipeline installation and maintenance configurations:

  • Two-Piece Split Body: The valve body is split into two parts (a main body and a cap). It offers a cost-effective design with a minimized leak path, commonly used in standard industrial applications.
  • Three-Piece Split Body: The body consists of one central piece housing the ball and two end pieces. This is the most popular design for high-pressure systems because it allows for easy in-line maintenance and inspection without fully disrupting the pipeline.
  • Top Entry: This design allows maintenance personnel to access all internal valve components (including the ball and seats) from the top flange without removing the valve from the pipeline. It is highly favored in offshore or underground installations.
  • Fully Welded Body: The body is completely welded together, eliminating external bolt paths and potential leak points. This type is heavily utilized in buried oil and gas pipelines and subsea applications where absolute environmental containment is required.

3. Uses and Critical Applications

Trunnion Mounted Ball Valves are built for extreme and high-capacity environments. They are widely used across the following sectors:

  • Oil & Gas Pipelines: Extensively used in long-distance midstream transmission lines for oil and natural gas, where handling large diameters (up to 60”+) and high pressures is mandatory.
  • Refineries & Petrochemicals: Essential for isolating high-temperature hydrocarbons, volatile chemicals, and hazardous process media.
  • LNG (Liquefied Natural Gas): Special cryogenic versions of TMBVs are used to handle liquid natural gas at temperatures as low as -196°C.
  • Power Generation: Used in high-pressure cooling water, boiler feed water, and main steam isolation systems.
  • Water Transmission: Employed in heavy municipal water infrastructure and high-pressure desalination systems.

4. Key Technical Specifications

When engineers specify a Trunnion Mounted Ball Valve, they look at adherence to global quality standards and rigid operating boundaries:

  • Size Range: Typically available from 2” up to 60” or larger.
  • Pressure Ratings: Designed to withstand severe pressures, ranging from ASME Class 150, 300, 600, 900, 1500, up to Class 2500.
  • Design Standards: Manufactured strictly in accordance with API 6D (Specification for Pipeline Valves), ASME B16.34, and ISO 14313.
  • Testing & Safety: Tested to meet API 598 or API 6D pressure testing. They are also certified fire-safe under API 607 or API 6FA to ensure the valve remains sealed even during an active plant fire.
  • Special Features: Frequently built with Double Block and Bleed (DBB) capability, emergency sealant injection ports, and anti-static devices.

5. Materials of Construction (MOC)

Because TMBVs manage punishing pressures and corrosive materials, their construction demands high-integrity metal alloys and robust sealing polymers:

  • Body and Adapter: Forged steels are highly preferred over castings for trunnion valves because of their uniform grain structure and lack of porosity. Common choices include Carbon Steel (ASTM A105, LF2), Stainless Steel (A182 F316, F304), and Duplex/Super Duplex (F51, F53, F55).
  • The Ball & Trunnion: Typically made from forged carbon steel plated with Electroless Nickel Plating (ENP) for corrosion resistance, or solid Stainless Steel (F316). For severe service, the ball might be hard-faced with Stellite or Tungsten Carbide.
  • Seat Rings: Can feature soft seats (PTFE, RPTFE, Devlon, Peek, or Nylon) for clean, lower-temperature fluids, or Metal-to-Metal seats hard-faced with Chromium Carbide or Tungsten Carbide for abrasive or high-temperature media.

Looking for a Leading Trunnion Mounted Ball Valve Manufacturer in India?

In high-pressure, severe-service piping operations, a single valve failure can lead to costly downtime or catastrophic safety hazards. Partnering with an API-certified, highly experienced manufacturer is non-negotiable.

For world-class manufacturing precision, reliable performance, and strict compliance with global energy standards, Oswal Valves is an industry benchmark. As one of the best Trunnion Mounted Ball Valve manufacturers in India, Oswal Valves produces high-integrity forged and cast trunnion valves engineered to endure the harshest pipeline conditions.

Discover their comprehensive range, request custom metallurgy, and secure your high-pressure operations by visiting the official Oswal Valves Trunnion Mounted Ball Valve Product Page.