What Is The Difference Between A Butterfly Valve And A Lug Valve?

Butterfly valve and camshaft valve (commonly known as camshaft butterfly valve) in structure, performance, installation methods, scope of application and so on are very different. Specific differences are as follows:
1.Structural features
Butterfly Valve
Basic structure: composed valve body, disc (circular closing member), valve stem and sealing device. Disc rotates 90° around the shaft to open and close.
Classification:
Structurally, it is divided into: center line butterfly valve (where the center of the disc overlaps with the stem axis), and single/double/triple eccentric butterfly valves (eccentric design reduces friction on the sealing surfaces).
By Sealing Material: soft seal (rubber, fluoride rubber, etc.) and hard seal (metal).
Features: Simple structure, light weight, fast opening and closing speed, but sealing performance is influenced by temperature and pressure.
Lug Valve (Lug-Type Butterfly Valve)
Special structures:
Lug Design: Convex is located on both sides of the valve body and has perforation or internal threaded holes for bolts. Insulation Structure: Some models feature insulated inner and outer shells to prevent erosion or thermal deformation of cryogenic fluids.
Disc Construction: Three layers (heat-resistant alloy steel + insulation material + stainless steel) are usually used to accommodate extreme temperature environments.
Features: lug design, flexible installation, insulation structure improves heat resistance, but relatively complex structure.
ii. Performance Differences
Sealing Performance
Butterfly valve: Sealing performance depends on the sealing material and structure. Soft seal butterfly valves has excellent sealing, but poor heat resistance; hard seal butterfly valves can withstand high temperature, but slightly inferior sealing.
Cam valves: usually have a triple seal structure (two soft seals + one metal seal) to provide more reliable sealing performance in high temperature, high pressure and corrosive media.
Flow and Pressure Drop
Butterfly valve: When the valve is fully open, fluid resistance is low, but the flow coefficient is limited by the valve body structure.
Lug Valves: The higher flow coefficient, the smaller pressure drop under the same flow rate, suitable for largeflow.
Warmth tolerance
Butterfly valves: Traditional butterfly valves have a limited temperature range (typically -40°C to 120°C). Lug Valve: Due to its insulating structure and special materials, it has a temperature resistance between -40°C and 700°C.
III. Installation and use
Installation Methods
Butterfly Valve:
Wafer Type: Bolted between two pipe flanges. Easy to install, but the bolts are long and leak easily due to creep.
Flange Type: Connect to pipe through flange, better stability, but higher price.
Lug Valve:
Lug Connection: Bolts are secured through lug holes without going through the entire valve body, reducing the risk of leakage.
Mounting Position: can be installed horizontally or vertically, or even at the end of a pipe (as an end valve), whereas traditional butterfly valves are usually limited to horizontal installation.
Maintenance and repair
Butterfly Valve: Simple in structure and easy to maintain, but multi-layered disc design (e.g. lug valve) may make maintenance more difficult.
Cam valves: Seals are replaceable, but multilayered structures require more careful maintenance.
IV. INTRODUCTION Scope of application
Butterfly Valve
General operating conditions: widely used in municipal water supply and drainage, chemical industry, electricity and other low-voltage, large-caliber pipelines, suitable for regulating or closing media. Limitations: Not suitable for extreme temperature or high-precision flow control applications.
Lug Valve
Special applications:
High/Low Temperature Environments: such as cooling water system and cryogenic storage tank pipelines thermal power plants.
Corrosive Media: acids and alkalis in chemical and sulfonate production systems, and transport of petroleum products.
High Flow Requirements: such as long-distance oil and gas pipelines.
Advantages: butterfly valve opens and closes quickly, lug structure is stable, suitable for sealing, temperature resistance, high flow control requirements.