What Is a Double Eccentric Butterfly Valve? Working, Advantages and Uses
Oil and gas lines, chemical processing units, power plants, water distribution networks and HVAC systems all need valves that perform well, last long and are easy to maintain. The double eccentric design is made for this kind of work, and it is the design behind the butterfly valves in the YDB Valves range.
In this blog, we explain what double eccentric means, how the valve works and seals, which materials go into it, what its key features are, and which types are available. We also cover where the valves are used, so you know what to look for when you choose one.
What Is a Double Eccentric Valve?
A double eccentric valve is a butterfly valve with an advanced design, built to regulate the flow of fluids across industrial applications. Two eccentricities are part of its construction, and they give the valve a tight seal while keeping wear low during operation.
The valve gives excellent flow control, and the torque it needs is minimal. For this reason, it suits applications where flow rates are high and conditions are challenging. Seat wear is kept down by the double eccentricity, which also adds to the lifespan of the valve and keeps the performance reliable over time.
How Is It Different From Traditional Butterfly Valves?
Compared with traditional butterfly valves, this design adds two offset axes. These cut the friction between the seal of the valve and its seat while the valve operates.
With less friction, the valve opens and closes more smoothly, the pressure drop is lower and the durability is better. The design is built for precise and efficient regulation of fluid flow, and water treatment and oil and gas are among the industries where it is commonly used.
How Does the Valve Work?
The working idea comes straight from the two offsets. Because of them, the disc makes minimal contact with the seat as it moves, which lowers the operational torque and extends the service life. The double offset disc keeps seat wear to a minimum, so the valve needs little torque to operate and offers a long cycle life.
How Does the Seat Seal?
The product page explains the seat sealing principle for two situations, depending on the side from which the medium enters.
When the disc is closed and the medium enters from the upstream side of the seat, the force of the medium presses the sealing ring against the sealing face of the disc. The elasticity and deformation of the sealing ring then guarantee the sealing performance.
When the disc is closed and the medium enters from the downstream side, a press board ring extrudes the seal. The sealing ring then overcomes the force of the medium and stays against the sealing face of the disc, which again guarantees the sealing performance.
This is why the valve is described as having bi-directional sealing performance.
What Is the Valve Made Of?
The product page gives a full material list for the high performance fire-safe butterfly valve. Each part has a standard material, and many parts have an optional one.
The body is cast steel as standard, with stainless steel or Monel as options. The disc is also cast steel, with stainless steel as an option. The spacer is stainless steel, with stainless steel or Monel listed as options.
For sealing, the seal ring is made of PTFE and stainless steel layers as standard, with stainless steel and graphite as an option. The seat is carbon steel with 1Cr, with stainless steel or Monel as options, and a metal seat tongue is made of stainless steel. Gaskets are graphite.
The bushings are PTFE with bronze, and lubricated bronze is the option. The retainer is NBR, with FPM as the option, and the retainer flange is carbon steel, with stainless steel or Monel as options. Screws are stainless steel, with 316 or Monel as options.
Around the shaft, the packing seat is stainless steel, with stainless steel or Monel as options. The packing is graphite, with PTFE as the option, and the packing bushing is stainless steel. The yoke and the lever are carbon steel, and the limit disc is carbon steel with stainless steel as the option. A second retainer is also carbon steel, with stainless steel as the option.
What Are the Key Features?
The product page lists six key features of the valve:
Double offset disc. It keeps seat wear to a minimum.
Bi-directional sealing. The seal holds from both sides.
Low torque and a long cycle life. These come from the double offset design.
Compact, lightweight construction. The valve is easy on space and weight.
On/off and throttling service. The valve can be used for either.
Four types. It is available in wafer, flanged, welded and expansion types.
Which Types Are Available?
The product range has five valves, and they cover the wafer, flanged, welded and expansion types.
Double Eccentric Wafer Butterfly Valve
The wafer valve has a compact, wafer-style design. It gives reliable sealing in both directions and wears the seat less. Because the double eccentric design limits contact between the disc and the seat, the torque needed is lower and the service life is longer. Choose it for industrial systems that are short on space but still need high performance.
Double Eccentric Welding Butterfly Valve
The welding type is made for permanent connections of high integrity. Because its ends are welded, the leak points that come with flanges are removed. The double offset geometry lowers friction when the valve opens and closes, so the operation is smoother and the seat lasts longer. Oil and gas, petrochemical and steam lines running at high pressure are where it fits.
Dual Eccentric Flange Type Cast Structure Butterfly Valve
This cast valve with flanged ends is built heavy-duty. Its structure is strong, and it resists deformation when pressure is applied. The dual eccentric disc touches the seat less, so wear drops and the sealing improves. It is meant for harsh settings like chemical processing and power plants.
Expansion Butterfly Valve
The expansion type absorbs pipeline expansion, vibration and misalignment. It keeps the system stable and leak-free, and it combines flexible movement with reliable shut-off. It is widely used in systems for HVAC, water supply and infrastructure that need dynamic adjustment.
Double Eccentric Flange Butterfly Valve
This is the standard flanged version, built with double offset construction. It offers excellent throttling and shut-off. The offset disc lowers the stress on the seat and improves longevity. Power stations, process industries and water treatment plants that need accurate control of flow, along with easy access for maintenance, will find it ideal.
Where Are These Valves Used?
The product page lists six areas of use. The valves are used on oil and gas pipelines and in chemical processing. Power plants and utilities use them, and so do water distribution and desalination, HVAC systems and industrial flow systems.
What Choices Do You Have When You Order?
The range gives you a clear set of choices. You can pick the type: wafer, flanged, welded or expansion. You can choose the standard material for each part or one of the optional materials from the list above, and you can pick stainless steel or Monel for the body where these options are listed. You can also choose the service, since the valve works for on/off and for throttling.
A Quick Recap
To sum up, the double eccentric design has two offset axes that cut friction between the seal and the seat. This gives smoother opening and closing, lower pressure drops, better durability, minimal torque, reduced seat wear and a long cycle life. The valve seals from both directions, has a compact and lightweight construction, and works in on/off and throttling service. It is available in wafer, flanged, welded and expansion types.
Where Can You Find the Full Specifications?
For the complete specifications, you can download the butterfly valve catalogue from our product page. The page also covers the material list, the sealing structure, the principle of seat sealing, the key features and the product types.
If you need other valves along with butterfly valves, YDB Valves LLP also offers double block and bleed valves, ball valves, instrumentation valves, high pressure needle valves, high pressure DBB needle valves, injection quill valves, gate, globe and check valves in cast steel and forged steel, and tube fittings. The company website also has pages on About us, Infrastructure, Quality, Certifications, Contacts and Enquiry.
Frequently Asked Questions
1. What does double eccentric mean in a butterfly valve?
It means the valve has two offset axes in its construction. These offsets cut the friction between the seal and the seat while the valve operates, which gives smoother opening and closing and reduced seat wear.
2. Can the valve seal from both sides?
Yes. The valve has bi-directional sealing performance. The sealing ring guarantees the seal whether the medium enters from the upstream side or from the downstream side of the seat. This is why bi-directional sealing is listed among the key features.
3. Which types are available?
The valve is available in wafer, flanged, welded and expansion types. The product range lists five valves that cover these types.
4. Can the valve be used for throttling?
Yes. It works for on/off service and for throttling, and it needs little torque to operate while offering a long cycle life. Compact, lightweight construction is listed among its key features as well.
5. Where is the valve used?
It is used on oil and gas pipelines, in chemical processing, in power plants and utilities, in water distribution and desalination, in HVAC systems and in industrial flow systems.
Looking for Butterfly Valves? Talk to YDB Valves
YDB Valves LLP is a pioneer manufacturer and supplier based in Vasai East, Palghar, with good experience in the designing and manufacturing of new concept instrumentation valves. If you need a double eccentric butterfly valve for your application, you can request a quote or download the catalogue from our website.
Our head office is at Y-21, Khan Real Industrial Estate, N. H. 08, Pelhar, Vasai Phata, Vasai East, Palghar – 401208, India.
- Request a Quote, or write to info@ydbvalves.com or call +91-80 8701 0270
- Download the catalogue to see the full product range
