A butterfly valve is a common type of industrial valve. It uses a butterfly-like round disc to control the flow. A butterfly valve is able to control liquid flow through a pipe without any significant impact on the other side.
A butterfly valve is designed to be a highly efficient option when controlling flow through a pipeline, which saves both time and money. Its benefits make it a highly preferred choice in many applications.
There are different types of butterfly valves available in the market. The two most common types are double offset and triple offset butterfly valves. The main difference between a double-offset and a triple-offset butterfly valve is their structure. In double-offset models, the stem and disc deviate from their center. This results in less scraping and over-compression, which increases the valve’s lifetime.
If you want to know more about the difference between double offset and triple offset butterfly valves, continue reading this article.
What is Double Offset Butterfly Valve?
A double offset butterfly valve is characterized by two counterbalance contrasts. The first offset is near the center of the valve body, where the stem attaches. This offset allows the valve to seal without any friction, while the second offset allows the valve to open with minimal friction. This means that it can be used for a variety of applications.
A double offset butterfly valve differs from a symmetric butterfly valve in two major ways. The first is the disc itself. The disc is shaped like an oval, while the second is parallel to the flow. The disc is also deformed in a unique way. Its asymmetric shape enables it to reduce pressure loss while reducing seat wear. In addition, it is able to accommodate multiple operating modes.
Pros and Cons of a Double Offset Butterfly Valve
Pros of Double Offset Butterfly Valve
Reduced Wear and Tear
The design of the double offset butterfly valve significantly reduces wear and tear on the valve seat and disc.
The offset shaft and cone-shaped sealing mechanism allow for a tight seal with minimal friction during operation, contributing to increased durability.
Lower Operating Torque
Compared to the traditional butterfly valve, the double offset design requires lower operating torque.
This means that the valve can be easily and efficiently actuated, making it suitable for applications where lower torque requirements are advantageous.
Extended Service Life
The reduced friction and wear, combined with lower operating torque, contribute to an extended service life for double-offset butterfly valves.
This makes them a cost-effective choice in the long run, as they require less frequent maintenance and replacement.
Enhanced Sealing Performance
The double offset configuration improves the sealing performance of the valve.
The offset shaft allows the disc to move away from the seat rapidly during the initial opening, minimizing contact and reducing wear.
This results in improved sealing integrity over time.
Versatility in Applications
Double offset butterfly valves are versatile and find applications in various industries, including oil and gas, petrochemical, water treatment, and more.
Their ability to handle high pressures and temperatures makes them suitable for diverse operating conditions.
Cons of Double Offset Butterfly Valve
Cost
Double-offset butterfly valves can be more expensive upfront compared to traditional butterfly valves.
The advanced design and materials used in manufacturing contribute to a higher initial cost.
However, this cost may be justified by the long-term benefits.
Complex Design
The double-offset butterfly valve has a more complex design than the standard butterfly valve.
The additional features, such as the offset shaft and cone-shaped sealing mechanism, may require more intricate manufacturing processes, potentially increasing maintenance complexities.
Limited to Certain Sizes
While suitable for various applications, double-offset butterfly valves are more commonly available in larger sizes.
This limitation may affect their use in smaller pipelines or applications where space is a constraint.
Sensitive to Contaminants
The precision required for the sealing mechanism makes double-offset butterfly valves sensitive to contaminants in the fluid.
Particles or debris in the flow may impact the sealing performance, requiring proper filtration and maintenance.
Potential for Cavitation
In certain conditions, double-offset butterfly valves may be susceptible to cavitation, especially during rapid changes in flow.
Cavitation can lead to erosion and damage to valve components, necessitating careful consideration of operating conditions.
What is Triple Offset Butterfly Valve?
The triple name offset indicates that the disc is not vertically centered and slopes up and down. As a result, it appears to be off-balance. The stem connects the disc to the valve body and, in turn, creates a third offset, which is the stem’s thickness from the flat side to a rounded tip. Because of this, the triple offset butterfly valve has a lower maximum capacity than a flat disc valve.
The triple offset butterfly valve is an effective, high-pressure valve that has many benefits. Its design features a metal-to-metal sealing arrangement that virtually eliminates disc-to-seat rubbing, which causes wear and a shorter life span. A triple offset butterfly valve is a high-performance valve that closes with zero leakage. The offset angle eliminates rubbing between the seat ring and the seal, which results in a repeatable, zero leak shutoff.
Pros and Cons of Triple Offset Butterfly Valve
Pros of Triple Offset Butterfly Valve
Bubble-Tight Sealing
The triple offset design provides bubble-tight sealing, ensuring a complete and tight closure of the valve.
This is particularly advantageous in applications where leakage prevention is critical, such as in high-pressure or hazardous fluid environments.
Minimal Wear and Tear
The continuous contact-less rotation and seating characteristic of the triple offset design result in minimal wear and tear.
This leads to an extended service life and reduced maintenance requirements, making it a cost-effective choice in the long run.
High-Temperature Resistance
Triple offset butterfly valves are suitable for high-temperature applications due to the use of materials that can withstand elevated temperatures.
This makes them ideal for industries such as petrochemical, refining, and power generation.
Bi-Directional Sealing
The triple offset design allows for bidirectional sealing, meaning the valve can provide effective closure regardless of the flow direction.
This feature enhances the versatility of the valve and ensures reliable performance in varied operating conditions.
Reduced Torque Requirement
Compared to traditional butterfly valves, triple offset designs generally require lower torque for operation.
This contributes to efficient actuation and ease of use, especially in large-sized valves.
Cons of Triple Offset Butterfly Valves
Higher Initial Cost
Triple offset butterfly valves tend to have a higher upfront cost compared to traditional butterfly valves.
The advanced design, precision manufacturing, and high-quality materials contribute to this increased cost.
However, the long-term benefits may justify the initial investment.
Complex Design and Manufacturing
The intricate design of triple offset butterfly valves, including the conical seating, requires precision manufacturing.
This complexity can lead to higher production costs and potentially longer lead times for procurement.
Sensitivity to Contaminants
The precision required for the triple offset design makes these valves sensitive to contaminants in the fluid.
Foreign particles in the flow can affect the sealing mechanism, emphasizing the need for proper filtration and maintenance.
Limited to Certain Sizes
While available in various sizes, triple-offset butterfly valves are more commonly used in larger applications.
This limitation may impact their use in smaller pipelines or systems where space constraints are a consideration.
Specialized Applications
Triple offset butterfly valves are often chosen for applications where bubble-tight sealing, high temperatures, and bidirectional capabilities are critical.
However, for less demanding applications, the additional features may not be necessary, making them potentially over-engineered.
Difference between Double Offset and Triple Offset Butterfly Valve
The main difference between double offset and triple offset butterfly valves is in the seat material. While double offset valves have soft seating material, triple offset comes with a metal seat. Another difference is pressure sensitivity and temperature fluctuations. Double offset valves are sensitive to pressure and temperature, but triple offset valves are not sensitive.
The Double Offset Butterfly Valve is better suited for bubble-tight sealing, while the triple offset butterfly valve is better suited for high temperatures, high pressure, and abrasive media. In addition, this valve has a high sealing surface and requires less maintenance. It also offers longer life than the double offset butterfly valve, which makes it ideal for applications involving high temperatures or corrosive media.
The differences between the double offset butterfly and the triple offset butterfly valve are significant. In addition, the metal seats of triple-offset valves can accommodate higher pressures than double-offset versions and require less torque. While the double-flanged butterfly valves are less expensive than triple-offset varieties, they are not ideal for high-pressure applications and unusual materials.
Double offset valves have low seat friction, whereas triple offset valves have very low friction. The seat is triple offset valves last longer than the double offset seat. Triple offset valves are often used in severe and critical applications, while double offset valves are used for on, off, and throttling functions.
About Xintai: Your Reliable Valve Manufacturer
XINTAI Valve Group Co., Ltd., established in 1998, stands as a prominent force in the valve manufacturing industry, seamlessly integrating research and development, casting, production, and sales.
Situated in the Longwan Konggang New District of Wenzhou, the group boasts cutting-edge technologies and operates from four manufacturing bases, equipped with eight advanced casting production lines.
Their expansive 32,000 square meters workshop houses modern facilities, including R & D centers and operational hubs.
With an impressive annual production exceeding 270,000 valves since the inception of their casting factory in 1998, XINTAI has established itself as one of the largest manufacturers of casting valves in Wenzhou.
The company’s commitment to quality is evident through its ISO9001 certification, domestic TS security certification, CE, OHSAS18001, and API certifications, ensuring accredited quality and adherence to industry standards.
XINTAI Valve Group takes pride in its leading forging process, crafting valves with exceptional strength suitable for systems with high-pressure and high-temperature requirements.
The company provides custom valve solutions, offering a comprehensive range of valve products, including the following:
- Control valves
- Cryogenic valves
- Gate valves
- Globe valves
- Ball valves
- Check valves
- Butterfly valves
- Power station valves
- Oxygen valves
- Hydraulic control valves
- Thread valves
- Antibiotic valves
With three strategically positioned offices, two marketing centers, and an inspection center, XINTAI Valve Group continues to be a trusted name in the industrial valve manufacturing sector, delivering reliable and innovative solutions to industries globally.
