Bellow Globe Valve
Bellow Globe Valve
※ Low Fugitive Emission
※ Size Range: DN15 to DN500
※ Class Range: PN10 to PN40
※ Design STD.: EN558-1
※ Bellow Seal Globe Valve Manufacturer
Recent researches on process plant emissions have shown that valves in pipes are responsible for more than 70% of leakages. Environmental contamination, production loss, process issues, and energy losses are all caused by these leaks.
It is important to stop these leaks in light of the current emphasis on pollution protection and energy conservation. Leaks cannot be completely eradicated even with a good selection, installation, and periodic and preventative maintenance on traditional valves. Even though the performance appears to be good at first, it will eventually leak from the gland after a few procedures. To answer this problem Bellow Sealed Globe Valves manufacturers came up with the idea to design valves with bellow seals instead of normal gland packing. As a result, the use of bellow seal valves is on the rise. Bellow Seal Valves are employed because they are capable of complying with a variety of emission regulations.
What is Bellow sealed Globe Valve?
A Bellow Sealed Valve is a type of industrial process valve that is meant to minimize valve leakage. It is often referred to as a ‘Zero-Leak Valve’ or an ‘Emission Free Valve.’
A Bellows sealed globe valve is a specially developed valve for use in an industry that deals with noxious fluids, where even minor leaks can be disastrous. With the rapid rise of new companies such as the chemical industries, nuclear industries, pipelines have become more filled with combustible, dangerous, highly poisonous, and toxic media. There is a higher threat of leakage, explosion, and health concerns. As a result, the valves used in these pipelines and systems must meet strict leakage and sealing standards.
The invention of the bellow seal globe valve was inspired by the necessity for a completely different way to achieve the needed sealing and redundancy.
Construction & Working: Bellow Sealed Globe Valve
In these valves, the bellow cartridge is connected with both valve stem at the bottom and valve bonnet (cover) at the top end. The bellow cartridge has a series of convoluted layers, which compress or expand depending on the movement of the valve stem. In simple words, when the Valve is open, the bellow is compressed, and when the Valve is closed, the bellow is extended. It is crucial to install the Valve bodies correctly.
The bellows can be sealed to the Valves in two ways.
- In the first type of installation, bellow can be welded to the Valve stem at the top and the Valve body at the bottom. In this situation, the process fluid is confined within the bellow;
- In the second approach, the bellow is welded to the valve stem at the bottom and the body at the top. In this instance, the process fluid is confined in the annular zone between the Valve Bonnet and the bellow (from the outside).
The bellow is an important component that serves as the heart of the bellow seal Valves. The valve must have a stem with only linear movement to prevent the bellow from twisting. This is achieved by utilizing a sleeve-nut at the Yoke part of the Valve Bonnet. A handwheel is attached to the sleeve nut, converting the handwheel’s rotating motion into a linear motion in the valve stem.
Bellow Types: Bellow Sealed Globe Valves
A Bellow seal globe valve is distinguished by its metal bellows. Bellows come in two varieties:
- Formed Bellow: The flat sheet is rolled into a tube and longitudinal fusion welding is used to create the formed bellow. The tube is then manually shaped into a bellow with rounded, evenly spaced folds.
- Leaf welded Bellow: The washer-like plates of thin metal are welded with each other in this design. On both the interior and exterior of the washer-like plate, welding is done. Welded leaf bellows have more folds per unit length.
Both formed and welded-leaf bellows have the same range of movement in each fold. As a result, mechanically formed bellows are two to three times longer than their welded leaf counterparts at the same stroke rate.
Technical Specification: Bellow Sealed Globe Valve
- Size Range : NPS 1/4 to NPS 4
- Class Range : ANSI 150 to 2500
- Design Standard : ISO 15848, ASME, DIN & DN.
- End Connection : Threaded, Flanged, and Welded.
- Operation : Manual, Pneumatic, and Electric actuation.
Features and Benefits: Bellow Sealed Globe Valve
- The role of the traditional gland is replaced with flexible metallic bellows, which reduces maintenance frequency and costs.
- Bellows are made of Inconel 625, which is a multi-ply, welded seam material with a longer life span.
- The bellow is welded to the stem and bonnet to guarantee that there is no leakage through the gland, preventing dangerous substances from entering the atmosphere.
- Flanged connections are replaced with screwed and seal welded joints to ensure no leakage (the valve is thus hermetically sealed).
- Valve seating can be repaired by lapping the body seat and replacing the disc, which can be done in the field or at the end user’s shop.
- The vacuum brazed body seat replaces the traditional threaded seat, removing a possible leak path and lowering maintenance costs.
Application: Bellow Sealed Globe Valve
Process Industries have main concerns related to environmental hazards and process economy, some of the applications where these valves can be used in the systems that carry:
- Fluids at high temperatures.
- Vacuum Conditions.
- Hazardous Fluids and Petrochemicals.
- Nuclear power plants & Heavy water.
- Costly fluid media, etc.
Difference Between Bellow Sealed Globe Valve and Normal Globe Valve
- The bellow seal globe valve has the better sealing capability and is more effective than the regular globe valve in ensuring the safety of pipelines carrying hazardous media.
- The bellows valve’s interior components are composed of stainless steel, which can resist temperatures up to 425°C. The Bellow Sealed Globe Valve has a life span of more than three years when compared to the normal Globe Valve. In a system where hot oil is being carried, a bellow sealed valve is chosen over standard seal valves to ensure output quality and minimize direct operating costs.
- The valve stem is not in tight contact with the packing on the normal globe valve, producing significant leak rates at high temperatures.
- To provide adequate sealing performance, the bellow seal globe valves with strong tension and compression qualities can be employed instead of gland packing.
- In general, the bellow globe valve is utilized for thin media pipelines such as ammonia since the pipeline will only leak if the bellows of the bellow seal globe valve are damaged. The normal globe valve sealed by gland packing, on the other hand, has a lower sealing performance.
Bellow sealed globe valve meet the needs and conditions of a processing plant’s operational economy. This is especially true when it comes to the flow and control capabilities that Bellow sealed globe valve manufacturers provide within the processing system. Furthermore, for Demanding applications, a Bellow sealed valve provides the greatest lifetime ownership cost choice among available valve types, and its purchase price becomes minor when compared to the cost of maintenance and processing stoppages required when other valve types are employed instead.
The non-negotiable criteria of personal and environmental safety enforced on process industries by regulating authorities, however, overshadow even the above concerns. Other than the Bellow sealed globe valves, there is presently no technically competent and efficient choice available in this market.
In this article, we as a Bellow Sealed Globe Valve manufacturer tried to provide basic information about this valve. For more knowledge on how to select a proper valve according to your requirement, you can always contact our experts.