Bellows Seal Globe Valves - Bellow Valve

What is a Bellow Valve?

A Bellows Valve is a specially designed valve suitable for use in industries dealing with a hazardous medium where even minute leakages can be extremely critical. With the exponential growth of new industries such as the chemical and nuclear industries, there is a growing abundance of flammable, hazardous, extremely poisonous, and toxic media flowing through the pipelines. This creates a high risk of leakage, explosion, and health hazards. So, the valves used in such pipes and systems have specific stringent leakage and sealing requirements.

The need for a completely different approach required for the desired sealing & redundancy has led to the development of Bellow Seal Globe Valve.

Design of Bellows Seal Globe Valves

OS&Y Structure
- The structure features a nonrotational stem and non-lifting handle so that the bellows are not twisted.
Gland Packing
- This blocks external leakage in the event of bellows breakage. MV, forged steel, cast steel, SUS 20K: Expanded graphite packing SUS 10K, 150lb: Reinforced PTFE + PTFE packing
Bolted Bonnet Structure
- The bolted bonnet structure provides simple maintenance and management.
- The bolt-tightened structure ensures reliable fastening.
Upper gasket
- An expanded graphite seat is used for the upper gasket.
- This blocks external leakage in the event of bellows breakage.
Lower gasket
- External leakage is blocked with the use of a high-quality gasket. MV, forged steel, cast steel, SUS 20K: Expanded graphic gasket SUS 10K, 150lb: Reinforced PTFE gasket
Bellows
- Hydroulic multi-layer bellows. SUS316L, which features excellent pressure and corrosion resistance, is used.
Seat surfaces
- Both seat surfaces with excellent jamming and abrasion resistance. (Optional for SUS valves)
Valve body
- Supports ductile cast iron (FCD-S), stainless steel (SCS13A), (SCS14A), cast steel (ASTM A216-WCB), and forged steel (ASTM A105).

Advantages of Bellows Seal Globe Valves

The design of the bellows seal globe valve is better than that of the ordinary globe valve. So, what are the advantages of bellows seal globe valves compared with ordinary ones?

The bellows seal globe valve has no leakage and is applied to a high-risk medium.
The common globe valve is sealed with packing, and a slide will occur between the valve stem and packing so that the valve is easy to leak at low temperatures.
Bellows seal globe valves use closed bellows which can be stretched and compressed to replace packing seals, effectively preventing leakage caused by packing losses. Generally, these valves are used for transmission of the medium with strong permeability. For instance, there is usually no leakage occurring to bellows seal globe valves for the hydrogen system, as long as bellows are not damaged. However, the common globe valve is sealed with packing, which is easy to cause leakage.
The bellows seal globe valve can cut off the flow of media and the opening or closing stroke of the valve stem is relatively short. Because the change of the seat opening is proportional to the stroke of the disc, the valve is an ideal choice for flow regulation. Therefore, this type of valve is very suitable for regulating or cutting off the flow, and for throttling.
Double seals (bellows+packing). If bellows fail, valve stem packing will avoid leakage. And the sealing meets international standards.
No fluid loss and energy loss reduction.
Long service life, reducing maintenance frequency and operating costs.
The robust bellows seal ensures zero leakage of the valve stem and provides maintenance-free.
PTFE soft seal materials are used for the valve seat for gas media to improve the sealing of the valve.
The valve seat with high-temperature resistance (≤425℃) adopts the conical surface and hard sealing.

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