Bellows seal globe valves, especially those compliant with ASME Section III NB, are essential in nuclear-grade piping systems where zero leakage is a strict requirement. At Babcock Valves, we apply advanced materials and proven design methods to meet these high-performance demands.
In environments such as nuclear power plants, absolute reliability is a non-negotiable standard. Any potential leakage to the atmosphere, especially in circuits handling radioactive or hazardous fluids, must be entirely avoided. This is where bellows seal valves play a critical role.
We have recently supplied a 2” Class 1500# Y-pattern globe valve for a Spanish nuclear facility, built according to ASME Section III NB (Class 1). The valve is designed with bellows sealing technology, a construction method where a stainless steel bellows is welded both to the valve stem and bonnet. As the valve operates, the bellows compresses or extends, ensuring that the fluid never reaches the traditional stem packing area — the most common point of leakage in standard valves.
The materials used in this project include SA 105 for the body and bonnet, SA564 Gr.630 H1075 for the stem, chosen for its excellent mechanical strength, and AISI 321 stainless steel for the bellows, selected for its superior resistance to thermal fatigue and corrosion. All materials are in full compliance with nuclear standards and undergo strict quality control protocols. The valve is supplied bare shaft, ready to be fitted with a Limitorque SMB-000 actuator already installed at the plant.
At Babcock Valves, our bellows seal valves are designed for long-term service with zero leakage, certified for at least 10,000 full operation cycles without failure. The multi-ply bellows used in our valves increase fatigue resistance under thermal and pressure cycling, a critical factor in safety-related applications.
We manufacture both globe and gate bellows seal valves, in sizes from ½” to 24” and pressure classes ASME 150 to 2500, covering a wide range of applications including:
- Primary and secondary cooling systems in nuclear plants
- Toxic or flammable fluid lines in chemical processing
- High-purity or environmentally sensitive systems
To learn more about our special valve designs, including other nuclear-qualified models, visit our Special Valves page.
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