Views: 0 Author: J-VALVES Publish Time: 2026-04-28 Origin: Site
In high-pressure pipeline systems, a valve is not just a shutoff device. It must deliver stable sealing, controlled operating torque, pressure resistance, and long-term reliability. When the size reaches DN350, the pressure class rises to PN320, and the material requirement includes LF2 CL1, the valve design becomes a critical part of project safety and performance.
That is why many engineering projects choose a welded trunnion ball valve. It is not simply a standard ball valve with a different connection. It is a purpose-built solution for demanding service conditions.
Here is a simple breakdown:
DN350: Nominal diameter of 350 mm, suitable for medium-to-large pipeline systems.
PN320: Nominal pressure rating of 320 bar, which places the valve in a high-pressure category.
LF2: A low-temperature carbon steel material commonly used for improved toughness in cold service.
CL1: A specification marker often used in project or material requirements, depending on the governing standard.
Welded design: The valve body is connected to the pipeline by welding, improving integrity and reducing leak paths.
Trunnion-mounted structure: The ball is supported by trunnions, reducing operating torque and improving stability.
In practical terms, this valve is designed for high-pressure, low-temperature, and long-cycle operation.
A floating ball valve works well in smaller sizes and lower pressure classes. But as the valve gets larger and the system pressure increases, sealing load, torque, and durability become more difficult to manage.
A trunnion-mounted ball valve offers several important advantages:
Because the ball is mechanically supported, friction on the seats is more controlled. This makes operation easier, especially for large sizes such as DN350.
In high-pressure service, sealing stability is critical. The trunnion design helps distribute the pressure load more evenly across the seats.
For oil and gas, chemical processing, and energy transmission systems, long service intervals matter. A trunnion-mounted valve is a better fit for continuous duty.
At DN350 and beyond, valve performance becomes more sensitive to structure and torque. The trunnion design helps maintain reliability in larger pipelines.
Many high-pressure projects prefer welded ends instead of more complex flange connections. The reasons are straightforward:
Higher connection strength.
Welded construction creates a more integrated pipeline joint.
Fewer external leak points.
Compared with multiple flanges, welded ends reduce potential sealing interfaces.
Better for buried or long-life pipelines.
Welded valves are often preferred where frequent disassembly is not required.
More compact system layout.
In space-constrained facilities, welded designs often improve piping arrangement.
LF2 is commonly selected when low-temperature toughness is required. For valves, material selection is not about maximum hardness; it is about maintaining impact resistance and structural integrity under cold conditions.
LF2 helps by:
Supporting low-temperature operation
Reducing the risk of brittle failure
Improving reliability in cold-service environments
Maintaining stability during temperature fluctuations
When both high pressure and low temperature are involved, material selection must match the project specification precisely.
The DN350 PN320 LF2 CL1 welded trunnion ball valve is commonly used in:
1. Oil and gas pipelines
For high-pressure transmission, station isolation, and line shutoff.
2. Chemical processing systems
Where sealing integrity and pressure resistance are essential.
3. Power and energy facilities
For steam, utility lines, and auxiliary systems.
4. Low-temperature projects
Where LF2-type carbon steel is required by design.
5. Long-distance pipeline networks
Where welded construction and stable operation are priorities.
When choosing a valve, size and pressure class alone are not enough. Key factors include:
Gas, liquid, or slurry? Corrosive or clean? Low-temperature or ambient?
Low, normal, or elevated temperature directly affects materials and sealing design.
The welded end must match the pipeline specification and installation method.
Soft-seated or metal-seated? The right choice depends on the service conditions.
Large high-pressure valves often require careful torque and actuator matching.
Confirm compliance with project design standards, pressure testing, and inspection requirements.
The DN350 PN320 LF2 CL1 welded trunnion ball valve is valuable not because it has “high specs,” but because it solves several critical engineering problems at once:
Large diameter control
Stable high-pressure performance
Reliable welded connection
Lower operating torque
Better suitability for low-temperature service
For projects focused on safety, uptime, and long-term reliability, this is a practical engineering choice.
A trunnion ball valve supports the ball mechanically, making it better suited for larger sizes and higher pressures. A floating ball valve is more common in smaller, lower-pressure applications.
Usually not. Welded designs are intended more for long-term service than repeated disassembly.
Not automatically. Final suitability depends on the actual temperature range, impact testing requirements, and project specifications.
No. Pressure rating must be evaluated together with medium, temperature, corrosion risk, and applicable standards.
