What is The Difference Between Flanged and Lugged Butterfly Valves

When it comes to butterfly valves, one of the first decisions buyers face is choosing between a flanged butterfly valve and a lugged butterfly valve. At first glance, they look similar. Both are designed for flow regulation in pipelines, both are compact, and both are widely used in marine, HVAC, oil and gas, and water treatment systems. But the way they connect to pipelines—and how they’re used—sets them apart.

Flanged Butterfly Valves Full Connection and Easy Maintenance

A flanged butterfly valve has flanges on both sides of the body. These flanges bolt directly between two pipe flanges, creating a secure, full-face connection. Because of this design, they provide:

• Strong sealing performance: Perfect for high-pressure applications.

• Easy installation: The valve fits neatly between two matching flanges.

• Safe maintenance: You can remove the valve without disturbing the entire pipeline.

Flanged butterfly valves are often used in larger pipelines and systems that handle high pressure or require frequent maintenance. In marine systems, for example, they are common in engine cooling water lines or ballast systems where safety and reliability come first.

Lugged Butterfly Valves: Flexible and Space-Saving

A lugged butterfly valve has threaded inserts (or “lugs”) around the body. These lugs allow the valve to be bolted directly to pipe flanges on both sides. The key advantage? You can remove one side of the piping while the other side remains in service.

• Versatility: They can be used in both dead-end service and bi-directional flow.

• Compact design: Ideal for pipelines where space is limited.

• Cost efficiency: Typically lighter and more economical than fully flanged valves.

Lugged valves are often chosen for smaller pipelines or systems where compactness and flexibility matter more than maximum strength. In shipboard piping, they’re handy in auxiliary systems or secondary water lines where space is tight.

Key Differences at a Glance

• Connection: Flanged valves bolt between two pipe flanges, while lugged valves use threaded inserts for direct attachment.

• Strength: Flanged valves handle higher pressure and are safer for critical applications.

• Flexibility: Lugged valves allow one side of the pipeline to be disconnected without shutting down the whole system.

• Applications: Flanged for heavy-duty, high-pressure, critical systems. Lugged for compact, flexible, or secondary systems.

Which One Should You Choose

• Go for a flanged butterfly valve if you need durability, strong sealing, and high-pressure capability.

• Choose a lugged butterfly valve if space, weight, and easy isolation are more important.

Both designs play an essential role in marine and industrial systems. Partnering with a trusted marine valve manufacturer ensures you get valves made with the right materials, tested for reliability, and certified for global standards.