Butterfly Valve Parts: The Ultimate Guide

When dealing with complex piping systems, it’s no surprise that you’re looking for a reliable solution.

That’s why butterfly valves are so popular.

They offer reliability you can depend on while improving system efficiency and cost-effectiveness.

To understand all the parts of a butterfly valve and how they work together for optimal performance, you need an expert guide — The Ultimate Guide to Butterfly Valve Parts!

Here you will learn everything from crucial technical information about different valve components to how butterfly valves can help maximize efficiency and suggest product applications in various industries.

Video – What are the Components of a Butterfly Valve?

How Does a Butterfly Valve Work?

Butterfly valves regulate flow by starting, slowing, or stopping media in a pipe with low torque rotation.

This process is achieved by positioning the disc to open or close off the material flow at 90 degrees.

The basic construction of a butterfly valve consists of a body, seat, disc, and stem.

When the handle is turned in one direction or another, it pushes or pulls the disc away from its seated position, allowing fluid to pass through unimpeded.

When turned 180 degrees, this same handle sets the disc down on its seat and closes off any further material flow.

Main Parts Of Butterfly Valve

The butterfly valve is made up of 6 main parts that are essential to its functionality.

  • Butterfly valve body
  • The wafer-style body and Lug Style Butterfly valves
  • Disk
  • Stem: Wetted or Non-Wetted
  • Seat
  • Hand lever
  • Gear


Butterfly valve bodies provide secure installation and operate mainly without maintaining pressure within the system.

These valve bodies come in two main designs, wafer-style and lug-style.

The Wafer-Style Body

Wafer-type butterfly valves are a cost-effective way of controlling the flow of fluids in pipes and pipelines.

They are installed between two pipe flanges and gently restrict the flow in either direction without being opened or closed.

The alloy discs have ports that separate them from the flanges, preventing the backing up of pressure in systems designed for unidirectional flow.

These butterfly valves offer excellent performance and reliability across various industries.

They are designed with two lug bolts passed through holes on both sides of the valve and tightened securely with nuts.

A flexible seal is used between the edges of the valve body and the pipe flanges to prevent any leakage.

When choosing such a valve, it’s essential to consider factors such as the media type, maximum/minimum temperature range, and required pressure rating.

Lug Style Butterfly Valves

Featuring threads on their outer sides, they are uniquely designed to allow their valve and pipe flanges to be joined with just two bolts on either side.

This makes them both cost-effective and easy to install in any piping system.

As if that wasn’t enough, the valves are also renowned for offering excellent flow regulation capabilities, making them a favorite option for many industries.

Lug-style butterfly valves are an excellent choice for systems that require dead-end service.

These valves have a reliable setup that allows one side of the system to be disconnected without affecting the other side.

While lug valves tend to be used at lower pressures when installed for dead-end service, they can still keep up when placed between two pipe flanges at higher pressure levels – up to 150 psi.

They’re an excellent all-around option for any system with varying or moderate pressure requirements.


If you take a look at a butterfly valve, you’ll notice that there’s a disk inside the body of the valve. This disk is responsible for controlling the flow of fluid.

It works in a similar way to the gates or balls that are placed inside ball valves.

The disk can open and close, allowing fluid to either pass through or be blocked off.

Butterfly valves are the best when you’re looking for a snug fit, such as in plumbing or piping.

The disk features two types: Eccentric and Concentric.

The eccentric disc has a much more complex design than concentric.

The concentric disk’s stem passes through their common point of bliss to bring these two together as one.

Concentric disk valves are a great choice for applications requiring lower pressure, making them the go-to valve in many scenarios.

In contrast to a concentric disk, which features a stem running directly in line with the center of the valve.

An eccentric disk contains a stem that runs behind the centerline, meaning its flow direction is opposite. A good example of ‘opposites attract’!

The eccentric disk works its magic to make sure the seal and disk don’t get too chummy before the valve is completely closed.

This helps extend the life of the valve. The concentric disk is generally used for lower-pressure applications.


The stem is an essential component in butterfly valves; it connects the disc to the handwheel or actuator.

As the components that move during the valve operation, stems are built for either resilient protection or high-performance features.

The former design usually lies within the disc, while high-performance stems are exposed and typically come in contact with the fluid.

Both designs aim to ensure accurate and quick valve movements necessary for efficient valve operation.

The stem features two types of stems, both dedicated to different uses.


As an essential component of butterfly valves, the wetted stem is responsible for several important functions related to fluid flow.

It is used to support and guide the disc, as well as provide inlet pressure-balancing and back seat protection for the valve’s internals.


Unfortunately, wetted stems are very vulnerable to corrosion and erosion due to their exposed position in pipes.

So, it’s critical to use a material that can stand up to the challenges of being exposed to whatever flows through the pipeline regularly.


The seat of a butterfly valve is an integral part of functioning, so it’s imperative to understand the role of the seat.

Seats are designed like a round flat fence that runs along the inside diameter of the valve, and they are typically created with polymers to increase their leak-proof quality.

Depending on the design, the seat can be pressed or locked down or bonded onto the valve’s body, which helps create a seal when combined with the disk.

This prevents any fluid or gas from flowing through.

The seat of the butterfly valve is directly connected to the actuation method used.

Manually operated valves are equipped with handles and gears that allow the operator to manually open or close the valve.

Conversely, automatic butterfly valves come with actuators powered pneumatically, electrically, or hydraulically from an external source.

Such actuators feature mounting points for attachment to piping structures.

Hand Lever

Hand levers are an essential part of butterfly valves, allowing users to quickly and easily open or close the valve.

They are usually made of steel with a chemical treatment, and powder coat finishes to ensure they meet stringent inspection requirements.

Many hand levers have a handle and locking lever, allowing you to select between fully open, fully closed, or partially open, depending on your needs.

Hand levers can be used on small to medium-sized butterfly valves, making them incredibly versatile and easy to use.


For their exceptional performance, butterfly valves are embraced in a range of industries and applications.

From pharmaceuticals to food and beverage processing, they can be relied upon to provide efficient flow control.

If more torque is needed, a gearbox can be added to increase the torque but at a trade-off of decreased opening and closing speed.

These butterfly valves are also self-locking, so they cannot be back-driven by pressure or flow, which can provide a measure of safety and security to process operations.

For further convenience, some models will also include position indicators so that users know what the valve is doing without inspecting it in person.

Manual Actuation vs. Automatic Actuation

Manual Actuation

Manual actuation requires the operator to use a handwheel/crank to set the valve either open or closed.

This approach gives the user complete flexibility as there is no need for electrical power, meaning you can choose how you want your hydraulic flow regulated.

Manual actuation of butterfly valves is a popular solution for systems that don’t have access to power.

As they provide an efficient way to secure fast operation when a more energy-intensive model isn’t practical.

People opt for these valves over others because of their cost-effectiveness and long service life, which make them ideal for simple applications.

Furthermore, the handle or stem attached to the handwheel makes it easy to open and close the valve with minimal effort.

This eliminates the need to manually turn the wheel each time you want to adjust the water flow.

Manual actuation is a popular way of controlling butterfly valves, and there are two main kinds.

Lever-Operated Valves:

Lever-operated valves are often used in smaller designs since they allow you to set the valve into three perfect positions: open, closed, or partially open.

Gear-Operated Valves:

Gear-operated valves offer increased torque and the possibility to lock at a particular position. They also allow you to install position indicators, making controlling the valve much more effortless.

Both types of manual actuation provide solutions that make adjusted settings easier while offering precise control over flow rates.

Automated Actuation

Automated actuation is becoming increasingly popular in controlling valves, as its remote capabilities provide reliability and accuracy not achievable with manual controls.

Its safety features make it a top pick for large valve applications, so you can rest assured knowing your process is handled with the utmost care.

Thanks to fail-open or fail-close designs, you can be sure that your valves will stay in their intended positions even if the actuator fails.

This makes automated actuation the go-to choice for many industrial applications.

Electric Actuated Butterfly Valve:

Electric actuated butterfly valves are an excellent choice for anyone who needs to regularly control massive amounts of work or large valves. 

This type of valve uses an electric motor to turn the stem and gives you complete automatic control with the added convenience of electricity as its power source.

No hard labor is needed here, adjust the dial, and the machinery takes care of everything else.

Pneumatic Actuated Butterfly Valve:

Pneumatic actuated butterfly valves are handy for managing the flow of fluids.

These valves use compressed air to create movement in the diaphragm or piston, allowing the valve to open and close quickly.

They are used in various applications ranging from controlling the massive flow of water in dams to regulating the pressure in gas pipes.

This kind of valve is prevalent because it is versatile, lightweight, flexible, and easy to install and maintain.

Hydraulic Operated Butterfly Valve:

Those looking for a valve that requires a significant amount of strength to open will find hydraulic-operated butterfly valves to be the perfect solution.

Whether you’re dealing with high-pressure systems or need an extra layer of security, these valves will surely provide the power and performance you need.

A hydraulic actuator does all the hard work for you, easily moving your valve into an open or closed position.

This can be achieved when pressure is added to one side of the chamber and then released on the other.

A powerful spring also ensures that it remains in place once the valve is closed.

Applications for Butterfly Valves

Butterfly valves are used in a huge range of industries and applications, such as:

  • Water flow control for the food industry,
  • Pharmaceuticals
  • Chemical production.
  • Provide higher throttling capabilities due to their unique design
  • Quickly turn off or open rapidly to adjust the water pressure
  • Applicable across both indoor and outdoor settings in all types of industries.

Benefits of Butterfly Valves

Here are plenty of benefits you can expect when using Butterfly valves:

  • Quick, easy installation
  • Automatically control and regulate flow rates
  • Compact design requires minimal space
  • Low maintenance and long-lasting durability
  • Cost-effective to buy and operate
  • Highly resistant to corrosion and wear
  • Adjustable valve seat for maximum efficiency
  • Wide range of sizes, materials and actuators available
  • Improved safety due to fail-open or fail-close designs.
  • Ideal for controlling large valves in industrial applications.
  • Provide higher throttling capabilities than other control valves.
  • Can handle liquids and gasses with extreme temperatures and pressures.
  • Can quickly turn off or open rapidly to adjust water pressure with minimal cost characteristics.
  • Robust construction provides superior resistance to corrosion.
  • Suitable for indoor and outdoor settings in multiple industries.

With these benefits, butterfly valves are clearly the preferred choice for many industrial applications seeking cost-effective solutions with maximum efficiency.

Whether you need to control liquid or gas pressure, a butterfly valve is ideal for your project.

Make sure you understand their parts and applications, and you will be on the right track to finding the perfect solution for your needs.

Types of Butterfly Valve

Butterfly Valves are versatile tools that can come in various types depending on the application they will be used for.

Rubber-Lined Butterfly Valve

One type is the rubber-lined butterfly valve, which is a less expensive option with good sealing capabilities.

It is ideal for lower-temperature applications and can be found in 150-300# PN10-25 flanges.

GAR-SEAL Butterfly Valve

Plastic-lined valves are better suited for harsher conditions, such as corrosive chemicals.

The GAR-SEAL valve is a well-known example of a plastic-lined butterfly valve and is typically used with PN10 or 16 flanges.

Metal Butterfly Valve

Metal butterfly valves are designed for withstanding higher temperatures and pressures, ranging from PN10 to 160; plus, they have the added benefit of being fire resistant.

Lastly, metal valves come in single-offset, double-offset, and triple-offset configurations. There’s certainly a wide array of selections available regarding butterfly valves.


Butterfly valves are an excellent choice for water systems that require frequent adjustments as they open and close quickly to adjust water pressure with minimal cost.

Butterfly valves come in different types, such as rubber-lined, plastic-lined, or metal, allowing for versatile applications and the correct valve choice according to pressure requirements.

INOXCN offers a wide range of butterfly valves that are reliable, durable, and cost-effective, making them suitable for various industrial applications.

We aim to focus on the quality and performance of our valves, which is the sole reason why we have been doing wonders for 25 years.

With Inoxcnvalve.com, you can find the right product that fits your needs quickly and deliver to your doorstep!

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