A lug-type double eccentric butterfly valve is a very common and important type of industrial valve. It combines the advantages of a lug-type structure and a double eccentric design, making it suitable for various demanding applications. It connects to the pipe flange through bolt holes on the lugs, ensuring easy installation without the need for additional flanges or welding.
Advantages of Lug-Type Double Eccentric Butterfly Valves
Extended Service Life: The double eccentric design significantly reduces friction and mechanical wear between the valve disc and seat, with some products achieving up to 1 million operating cycles.
Reliable Sealing: High-performance seat materials (such as PTFE, TFM) and an automatic compensation structure ensure zero leakage under both pressure directions, maintaining a stable seal even under low pressure or vacuum conditions.
Low Torque Operation: The double eccentric structure reduces the torque required to open and close the valve, resulting in easier operation and lower actuator power requirements.
Easy Maintenance: The lug-type structure allows for single-sided pipe disassembly, and seat replacement does not require removal of the valve stem or disc, resulting in low maintenance costs.
Disadvantages of Lug-Type Double Eccentric Butterfly Valves
Limited Control Precision: In applications requiring precise flow or pressure control, it may not offer the same level of control as a dedicated regulating valve.
Limited Pressure Range: While it can withstand certain pressures, its pressure range is relatively narrow compared to some specialized high-pressure valves, limiting its use in ultra-high pressure applications.
Sealing Performance Depends on Conditions: While the double eccentric design aids in sealing, extreme conditions, such as media containing large particles or significant temperature fluctuations, may affect sealing performance and increase the risk of leakage.
Wear and Tear with Long-Term Use: Even with the reduced friction of the double eccentric design, long-term, frequent use will still cause some wear to the sealing surfaces, affecting lifespan and sealing performance.
Applications of Lug-Type Double Eccentric Butterfly Valves
Petrochemical Industry
Used in pipelines for transporting various oils, chemical raw materials, solvents, catalysts, and other media. Its metal-to-metal sealing provides resistance to high temperatures, high pressures, and corrosive media. These valves are commonly used in refinery and chemical plant applications, such as reactor feed/discharge lines, storage tank inlets/outlets, and flare systems.
Power Industry
In thermal power plants, they are used in boiler feedwater systems, cooling water circulation systems, and flue gas desulfurization (FGD) systems. They can withstand high-temperature water and steam. Examples include condenser circulating water inlet/outlet, fan outlet, dust collection system, and slurry pipelines in desulfurization towers.
Water and Wastewater Treatment
Used in municipal water supply and drainage networks, aeration tanks, sedimentation tanks, and sludge treatment systems in wastewater treatment plants. Their rubber or epoxy-coated butterfly discs effectively resist corrosion and abrasion from wastewater and sludge.
How to Select the Best Lug-Type Eccentric Butterfly Valve?
Pressure and Temperature Rating: Ensure the valve’s pressure rating (e.g., PN16, PN25, Class 150) and temperature range meet the application requirements.
Media Characteristics: The corrosiveness, presence of solid particles (abrasiveness), and viscosity of the medium determine the selection of valve body and sealing material (e.g., CF8M stainless steel body + STL hard alloy seal for harsh conditions).
Connection Standard: The lug dimensions must match the pipe flange standard (e.g., ANSI, DIN, JIS, GB).
Actuator Type: Select manual (handwheel, worm gear), electric, pneumatic, or hydraulic actuator based on automation requirements.
Sealing Requirements: Zero leakage (soft seal preferred) or high temperature/high pressure (metal seal preferred).
Summary
The lug-type eccentric butterfly valve is a versatile valve with excellent performance. It perfectly balances ease of installation and maintenance (lug type) with high performance and long service life (eccentric design), making it a preferred valve type for pipeline systems in heavy industries such as oil, chemical, power, and water treatment.
TEJI‘s lug-type eccentric butterfly valves feature bidirectional flow control, six-level leakage standard, and an excellent sealing performance due to its eccentric disc design. Contact us for more information.
