Double Flanged Butterfly Valve

What is a double-flanged butterfly valve?

This is a butterfly valve designed with two flanged ends on the inlet and outlet ports of the valve. This type of valve is installed in a pipeline that has flanges. The flanges on the pipeline must have the same size as those on the valve. Double flanged butterfly valve manufacturers produce these valves with holes on the flanges. The holes serve to hold the bolts that are used to connect the valve and the pipe together. The bolts are tightened using nuts to enhance a bubble-tight seal. These valves are more common in large dimensions since they are used in high-pressure applications. This design of valves makes installation, cleaning, repair, and maintenance easy as they can be dismantled easily for such operations. Double flanged butterfly valves are operated either manually or through actuators. The working principle of both the actuated and the manual valve is the same. These valves are used for on and off applications as well as in throttling fluid flow. 

Figure: Double flanged butterfly valves.

Components of a double flanged butterfly valves 

Body 

This is an external part of a double-flanged butterfly valve that serves to hold and house internal parts of the valve. The body is made very strong to ensure the valve can withstand fluid pressure as well as load arising from the weight of each valve component. Double flanged butterfly valve manufacturers make the valve body using strong metallic materials such as cast iron, ductile iron, carbon steel, stainless steel, and nickel alloys among others. Such materials are very strong and thus they help to enhance the high strength of the valves. 

Handwheel/actuator 

This is the component that provides the force needed to rotate the disc to open and close the valve. The handwheel/hand lever is used in manual valves and it is the component where the valve operator applies force to open/close the valve. The actuator is used in automatic and semi-automatic valves. 

Stem 

This is a component of double-flanged butterfly valves that are used to connect the handwheel and the valve disc. The stem gets the power to rotate the disc from the handwheel or actuator. 

Gearbox

This is component used in gear operated manual valves and it contains gear system used to multiply the torque applied by the valve operator. The gear system is connected to the valve handwheel where it obtains the torque. It transmits torque from handwheel to the valve stem.

Disc 

The disc is the part that is tasked to open and close the valve. The disc is connected to the valve actuator or handwheel through the stem. 

Seat 

This is a component that forms a surface for the disc to rest on when the valve is closed. Double flanged butterfly valve manufacturer design these valves with two seats. This two help to prevent fluid leakage once the valve is closed. 

Gasket 

This is a component used to prevent fluid leakage between the valve and pipe mating surfaces. The material used to make the gasket determines the operating temperature of the valve. 

Figure: Components of a double flanged butterfly valves.

How does a double-flanged butterfly valve work? 

A double-flanged butterfly valve operates by rotating the disc for an angle of 90^o degrees to open and close. The ability of the valve to turn the disc is enhanced by the power applied on the handwheel by the valve operator or by the actuator on automatic vales. To open a double-flanged butterfly valve, the handwheel is turned in an anticlockwise direction for a quarter that is 90^o degrees. This makes the valve stem connected to the disc turn the disc such that it becomes parallel to the fluid flow direction. This makes the valve create a free path that allows fluid to flow through the valve. To close the double flanged butterfly valve, the handwheel is again turned but in the opposite direction that is in the clockwise direction. This forces the disc to turn and become perpendicular to the pipe. As such, the fluid is blocked from flowing through the valve. Double flanged butterfly valve manufacturers design this valve such that turning the handwheel for an angle less than 90^o degrees opens the valve slightly allowing the valve for use in throttling applications. 

Figure: Working of a double flanged butterfly valve.

Types of double-flanged butterfly valves 

Manual double-flanged butterfly valves

This is a double-flanged butterfly valve that is operated manually. This means that a valve operator is needed to help in turning the handwheel to open, throttle, or close fluid flow. Double flanged butterfly valve manufacturers design these valves to operate using a handwheel or hand lever. The handwheel is preferred where there is high torque needed to open or close the valve. Handwheel operated valves are also designed with a gearbox. The gearbox contains a system of gears that help in torque multiplication making it easy to open and close the valve in high-pressure applications. The gearbox input shaft is connected to the handwheel. This makes the small torque applied on the handwheel to be amplified through the gearbox. Manual double-flanged butterfly valves are cheaper relative to the actuated ones. Also, double-flanged butterfly valve manufacturers design these valves so that they can be automated in the future if it becomes necessary. The main challenge associated with these valves is that they are tedious especially where valve operation is frequent or where a lot of torque is needed to open and close the fluid flow. 

Figure: Manual double flanged butterfly valve (with handwheel and gear box on the left and with hand lever on the right).

Actuated double-flanged butterfly valve 

This is a double-flanged butterfly valve that is operated using an actuator. This makes the valve fully automatic or semi-automatic. These valves are suitable for use in applications that need a lot of torque to open/close. Actuated double-flanged butterfly valves are more expensive compared to manual types. The high cost is due to the valve actuator due to its components and automation system. The automation system helps to determine when to close and open the valve. Double flanged butterfly valve manufacturers also design these valves for remote control required in most industrial applications. There are three types of actuated double-flanged butterfly valves which are: 

1. Pneumatic double flanged butterfly valve. This is a valve that uses a pneumatic actuator to open and close the fluid flow. These valves are suitable for use in all applications including food applications that need high levels of hygiene. This is because these valves use compressed air to operate and the air can be cleaned to ensure it does not contaminate the food product.
2. Electric double flanged butterfly valve. This is a double-flanged butterfly valve that uses an electric actuator. These valves are very common because of the availability of electricity. The actuator converts electrical energy into mechanical energy used to turn the valve disc to open and close the valve. 
3. Hydraulic double flanged butterfly valve. This is a valve that uses hydraulic fluid to operate. These valves are known for producing very high torque since the fluid used is incompressible. However, these valves are affected by temperature changes, and thus their use is limited to low-temperature applications. 

Figure: Actuated double flanged butterfly valve.

Factors to consider when selecting a double-flanged butterfly valve 

Type of media 

Double flanged butterfly valve manufacturers produce these valves for use in various fluids ranging from non-corrosive to corrosive. Corrosive fluids such as acids can damage a valve within a few days of use if the materials used to make that valve are not resistant to corrosion. As such, it is important to know the specific fluid that the valve will be used on to help the double-flanged butterfly valve manufacturer to advise or select the best valve for that application. 

Operating temperature 

Double flanged butterfly valve manufacturers make these valves using different materials. Some materials can withstand very high temperatures involved in applications such as steam plants and other materials like plastic and rubber are suited to low temperatures below 60^oC. Using the valve on the wrong temperature is dangerous as it may damage the valve or cause injuries to the valve operator. 

Working pressure 

Valves serve well if they are used at the pressure level recommended by the double-flanged butterfly valve manufacturer. Excess fluid pressure may cause fluid leakage through pipe-valve connections. If the fluid leaking is hazardous it may cause damage to the environment or valve operator. Also, such leakages lead to wastage of fluid being transported. 

Applications of double-flanged butterfly valves 

• Suitable for use in high-pressure and high-temperature applications. 
• Oil and gas transportation services. 
• Petroleum refinery industries. 
• Paper and pulp industries as they hardly get clogged. 
• Mining applications to help transport slurries and sludge. 
• They are used in firefighting applications. 
• Water supply and water treatment applications. 
• Steam power plants. 
• Food and beverage processing.

Advantages of double-flanged butterfly valves 

• Very strong compared to other butterfly valves. 
• These valves need only a quarter turn to open and close and thus they are fast operating. 
• Free from fluid leakage. 
• High-temperature applications. 
• Simple and compact in design. 
• These valves occupy smaller space when installed compared to other valves, such as globe valve. 
• They are easy to install, repair, and clean.

Disadvantages of double-flanged butterfly valves 

• These valves are heavy compared to other butterfly valves. 
• When the valve is open the disc remains in the fluid flow path which reduces flow pressure. 
• These valves are suitable for throttling use where pressure drop is low. 

Troubleshooting double-flanged butterfly valves 

The valve is hard to open/close 

• Foreign materials have been clogged in the valve. Open the valve and remove foreign materials. 

External fluid leakage 

• Worn out gasket. Replace the gasket. 
• Loose bolts and nuts. Tighten the bolts and nuts to attain the torque required by the double-flanged butterfly valve manufacturer. 
• Worn out O-rings. Replace the O-rings. 
• Excess fluid pressure. Ensure fluid pressure is up to the level recommended by the double-flanged butterfly valve manufacturer. 

Internal fluid leakage 

• Worn out O-rings. Replace the O-rings. 
• Damaged seat. Replace the seat. 
• Damaged or worn-out disc. Replace the disc. 
• Foreign materials in the valve. Clean off the materials. 

Summary 

The double flanged butterfly valve is a type of valve designed with two flanged ends one on the inlet and the other on the outlet end. The flanged ends have holes. This type of valve is connected to a pipe ends that have flanges and holes of the same size as the valve.

Double flanged butterfly valve manufacturers design these valves for use in high-pressure applications since they are very strong. These valves are more expensive compared to other butterfly valves. These valves are operated manually or by use of actuators like electric, pneumatic or hydraulic actuators. Double flanged butterfly valves are operated by turning the valve disc for a quarter turn in the anticlockwise direction to allow fluid flow. The valve is closed by turning the disc in the clockwise direction.