Triple eccentric butterfly valve is an advanced butterfly valve designed for high pressure, high temperature and severe working conditions, whose unique design structure and working principle make it an ideal solution for a wide range of industrial applications, including the chemical industry, natural gas, electric power, and metallurgy.
Definition and design principle
The term “triple eccentric” is used to describe this kind of butterfly valves that have a stem axis that deviates from both the centre of the disc and the centre of the body. Additionally, the seat slewing axis is at an angle to the axis of the valve body channel.
The first eccentricity: The stem axis does not coincide with the centre of the sealing surface. This reduces friction when the valve plate is switched on and off.
The second eccentricity: The offset of the stem axis from the centreline of the pipe, which avoids interference with the seal when the valve plate rotates.
The third eccentricity: A conical sealing surface (non-concentric cone structure) which ensures a frictionless seal when the valve is fully closed, while also significantly enhancing sealing performance.
Taloar triple eccentric butterfly valve’s design provides ever-stable quality to fully meet the valve requirements even under harsh working conditions. The triple eccentric butterfly valve is designed with angular eccentricity based on double eccentricity. In that way, the body can be separated quickly from the valve seat while the valve is operated. There is no friction between the inclined cone surface of the valve seat and the sealing surface of the body while the valve is closing. The operation torque is low to ensure two-way sealing and zero leakage.
The triple eccentric butterfly valve has its metal sealing material installed on the disc. The multi-layer combined seal, made of high-quality stainless steel + graphite + carbon fiber + PTFE + other materials, can effectively prevent the medium from scouring and wearing the valve seat in long-term service. Under the special medium working conditions, the integral all-metal or higher standard sealing materials can be selected. The valve seat annular sealing materials, assembled on the disc and replaceable, can be maintained in the pipelines on site.
The center line of the valve shaft deviates from both the center of the disc and the center of the body, the center line of the body forms certain angle with the inclined cone surface of the valve seat to ensure that there is no friction between the disc and the sealing surface of the valve seat while the valve is opened or closed, to achieve uniform sealing.
Working principle
The triple eccentric butterfly valve is designed to regulate the flow of fluid through the plate located within the valve body. When the valve is closed, the plate is in contact with the valve seat, preventing the fluid from passing through. Conversely, when the valve is open, the plate is separated from the valve seat, allowing the fluid to pass through. The eccentric design of the butterfly plate reduces the contact area between the plate and the valve seat when the valve is closed, thereby reducing the friction of the valve and the operating force required. Furthermore, the eccentric design of the butterfly plate minimizes the resistance of the fluid as it passes through the valve, thereby increasing the flow coefficient of the valve.
Opening process: Once the valve is opened, the valve plate begins to rotate around its axis, driven by the rotation of the shaft. The initial eccentric design of the valve plate ensures that it does not immediately come into contact with the seat. Instead, it is offset outwards, which reduces friction and facilitates a smoother opening process.
Closing process: As the valve closes, the valve plate gradually rotates and moves progressively towards the seat along the trajectory of the eccentric design. As the closing process continues, the plate moves closer to the sealing surface of the seat along its axis of rotation until it is fully sealed. The second and third eccentric designs facilitate a highly smooth sealing surface contact, thereby greatly reducing friction during the closing process and avoiding wear of the sealing surface.
Characteristics
(Here take Taloar triple eccentric butterfly valves as an example.)
The body is made of high-quality carbon steel, forged steel or stainless steel.
Multi-layer assembled valve seat sealing material ensures two-way sealing and zero leakage. It is resistant to medium scouring and wear, and can be maintained and replaced on site. It can offer stainless steel or satellite hard alloy for higher requirements.
The stainless-steel disc is designed with full bore to ensure medium circulation and provide maximum flow. The valve shaft is anti-blow-out structure design made of high-strength, anti-corrosion 17-4PH stainless steel.
The stainless-steel shaft sleeve is specially harden treated, resistant to high temperature and corrosion, perfectly fit to the valve shaft.
On site adjustable graphite packing and carbon fiber gasket offer dual seal to ensures seal tightness, longer service life.
Installation and maintenance
Inspection before installation:
Valve appearance check: Ensure that the valve is intact, paying particular attention to the sealing surface, plate, bearings and other parts, in order to guarantee that there are no defects or deformations.
Seal check: Ensure that the sealing ring, O-ring and other seals are intact and not ageing or broken. Replace the seals with new ones if necessary.
Pipeline inspection: Confirm that the pipeline size at the installation location is the same as the connection size of the valve. Ensure the cleanliness of the pipeline and avoid impurities from entering the valve.
Installation position selection
Valve direction: It is essential that the butterfly plate of the valve is correctly positioned in accordance with the direction of fluid flow during the installation process. As a general rule, the flow direction of the triple eccentric butterfly valve should align with the arrow indication on the valve body.
Installation position: When installing the triple eccentric butterfly valve, it is advisable to avoid environments where debris is likely to accumulate or corrosion occurs. Similarly, the valve should not be installed at the low point of the pipeline to prevent the accumulation of water or impurities, which could affect its performance.
Installation method
Flange connection: It is common practice to connect triple eccentric butterfly valves to the pipeline by flange. It is important to ensure that the flange surface is flat, that the sealing washer is correctly positioned, and that the bolts are tightened evenly and symmetrically to prevent poor sealing.
Threaded connection: For smaller valves, a threaded connection may be used. During installation, it is essential to ensure that the threads are properly aligned and that the bolts are not overtightened to prevent damage to the seals.
Support structure: In the case of larger triple eccentric butterfly valves, it is essential to set up an appropriate support structure in accordance with the weight of the valve during installation. This will help to prevent any deformation or leakage of the valve caused by its own weight.
Valve commissioning
Once the installation is complete, it is necessary to carry out either manual or automatic commissioning in order to guarantee that the valve can be opened and closed correctly.
It is important to ascertain whether the valve is capable of sealing completely in both the fully open and fully closed positions. It is essential to ensure that the actuator is correctly adjusted to guarantee optimal operation and sealing performance.
It is essential to conduct regular inspections and maintenance of the triple eccentric butterfly valve to guarantee its optimal functionality. Inspect the sealing surface, valve stem and transmission parts of the valve for wear or damage and replace or repair as necessary. It is also important to consider the installation and use of the valve in its environment, in order to avoid any damage or failure of the valve due to other factors.
Taloar high-performance triple eccentric butterfly valves are designed for sectional energy heating, power generation and crude oil transmission pipeline systems as well as for pipeline systems under harsh medium working conditions. Taloar products, manual or automatic control, demonstrate excellent product performance. Besides, Taloar provides on-site services and one-stop solutions for our clients.
Taloar is dedicated to offering the customers the highest quality triple eccentric butterfly valves, including triple eccentric flange butterfly valves , wafer butterfly valves, lug butterfly valves and welded butterfly valves. If you have any special customized requirements, please do not hesitate to contact us.
If you need to keep up with innovations and technological advancements in triple eccentric butterfly valves, Taloar will support you! For more details, please contact sales@taloar.com or WhatsApp 008618112507128.
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