Views: 0 Author: J-VALVES Publish Time: 2026-04-13 Origin: Site
In nuclear power plants, auxiliary systems play a critical role in maintaining safe and stable operation. These systems support cooling, feedwater, drainage, chemical treatment, fire protection, and other essential services. While they may not directly control the reactor core, their reliability is vital to overall plant safety.
For these demanding applications, the valve is not just a flow-control component. It must withstand pressure fluctuations, long service cycles, external vibration, and seismic events while maintaining dependable shutoff performance. That is why trunnion ball valves are often considered for nuclear auxiliary systems where stability, durability, and leak-tight performance are required.
Nuclear auxiliary systems operate under strict safety and quality expectations. A valve failure in these systems may affect process continuity, maintenance intervals, and in some cases plant safety margins.
Three requirements are especially important:
First, tight sealing performance is essential. Internal or external leakage can compromise system efficiency and create safety concerns.
Second, seismic resistance matters. Valves must remain functional under earthquake loads, piping movement, and structural vibration.
Third, long-term reliability is non-negotiable. Nuclear projects often demand extended service life, traceability, and controlled maintenance planning.
A trunnion ball valve uses top and bottom support for the ball, which reduces load on the seats and improves performance in high-pressure or large-diameter applications.
Compared with a floating ball valve, a trunnion-mounted design offers several advantages:
1. Lower and more stable operating torque
The ball is mechanically supported, so operating force remains more predictable.
2. Better shutoff control
Seat design can be optimized for low leakage and consistent sealing.
3. Suitable for high-pressure and large-bore service
This makes the valve a practical choice for demanding auxiliary lines.
4. Easier integration with automation
Trunnion ball valves can be paired with electric or pneumatic actuators for remote operation and interlock systems.
Meeting seismic and zero-leakage expectations requires more than a strong product brochure. It depends on the complete chain of design, materials, manufacturing, testing, and installation.
A valve intended for nuclear service should use a robust body, stable support arrangement, and well-controlled stem and bearing geometry.
Important design considerations include:
optimized body stiffness and wall thickness
precise alignment of stem, ball, and trunnion support
anti-loosening features
allowance for thermal expansion and piping movement
Nuclear auxiliary service often requires materials with strong pressure resistance, corrosion resistance, and fatigue resistance. Common options may include carbon steel, stainless steel, low-temperature steel, and other project-specified alloys.
Material control should ensure:
stable chemical composition
verified mechanical properties
no performance loss after welding or heat treatment
full traceability from raw material to finished product
“Zero leakage” is a project requirement that depends on design precision and validation. Typical sealing improvements include:
accurate machining of the ball and seat surfaces
controlled seat preload
fire-safe, anti-static, or wear-resistant sealing structures
multi-stage stem packing design
optional secondary sealing or purge arrangements
For nuclear-grade equipment, performance must be proven, not assumed. Common verification steps include:
shell strength testing
low- and high-pressure seat leakage testing
cycle or endurance testing
seismic-related qualification
non-destructive examination of critical parts
complete documentation and traceability review
Even the best valve can underperform if installation is poor. For nuclear auxiliary systems, correct piping alignment, proper support, controlled torque loading, and scheduled inspection are all essential.
ASME nuclear grade is not just a label. It represents a quality-driven framework focused on traceability, documentation, verification, and controlled manufacturing processes.
For a trunnion ball valve, it typically means:
complete design records
clear material traceability
controlled manufacturing procedures
inspectable test results
audit-ready quality documentation
This is why nuclear projects evaluate more than price. They also assess process control, compliance capability, and engineering experience.
Trunnion ball valves are commonly used in:
cooling water systems
auxiliary feedwater lines
chemical treatment branches
discharge and recovery pipelines
high-pressure isolation service
remotely operated safety-support circuits
In these applications, the goal is not simply mechanical strength. The real objective is stable, documented, long-term performance.
When choosing a valve for nuclear use, it is wise to review:
nuclear project experience
full material and inspection documentation
ability to customize to project specifications
seismic and leakage qualification capability
actuator compatibility
compliance with required standards and owner specifications
For nuclear auxiliary systems, a qualified valve supplier should provide more than equipment. It should provide an engineering solution with documentation that can stand up to review.
Nuclear auxiliary systems demand far more from valves than ordinary industrial service. Trunnion ball valves stand out because they offer strong structural stability, low operating torque, high-pressure suitability, and dependable sealing performance.
When design, materials, manufacturing, testing, and installation are controlled as one system, a trunnion ball valve can better meet the stringent seismic and zero-leakage expectations of ASME nuclear-grade projects. For nuclear power applications, that is not only a technical choice, but also a safety strategy.
Q1: Where are trunnion ball valves used in nuclear plants?
A1: They are commonly used in auxiliary cooling, feedwater, chemical treatment, discharge, recovery, and high-pressure isolation lines.
Q2: Does zero leakage mean absolutely no leakage at all?
A2: In engineering terms, it usually means extremely low leakage or a project-defined leakage limit verified by testing.
Q3: What mainly improves seismic performance?
A3: Body design, support structure, material strength, installation quality, and qualification testing all contribute.
