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Butterfly Valve

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What is a Butterfly Valve?

 

A butterfly valve is a shut-off valve with a relatively simple construction. In closed position, the disc blocks the valve bore while in open position, the disc is turned to allow flow. A quarter turn takes the valve from fully open to fully closed position, or opposite, and thus the butterfly valve allows for quick opening and closure.

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Benefits of Butterfly Valve
 
01/

Compact design
One of the primary benefits of butterfly valves is their compact and lightweight design. Compared to other types of valves, such as gate valves or ball valves, butterfly valves take up less space and are easier to install. Their lightweight construction means that they require less structural support, making them ideal for applications where weight is a concern.

02/

Ease of operation
Another advantage of butterfly valves is their ease of operation. These valves have a simple mechanism that allows for quick opening and closing. With just a quarter-turn of the handle or a lever, the valve can fully open or close, resulting in efficient flow control. This simplicity in operation makes butterfly valves suitable for both manual and automated systems.

03/

Excellent flow control capabilities
Butterfly valves also offer excellent flow control capabilities. Their spherical disc or plate design enables a streamlined flow path, reducing turbulence and pressure drop. The full-bore design of butterfly valves allows for unrestricted flow, resulting in minimal resistance and improved efficiency. Additionally, butterfly valves can be used for throttling applications, allowing precise control of the flow rate.

04/

Durable
Furthermore, butterfly valves are highly reliable and provide tight shut-off. The construction of these valves ensures a tight seal, preventing any leakage. This characteristic is particularly important in applications where the fluid needs to be completely blocked off to avoid contamination or for safety purposes. The durable materials used in butterfly valves make them resistant to wear and corrosion, guaranteeing a long service life.

05/

Easy to maintain
Maintenance of butterfly valves is relatively easy and cost-effective. Their simple design allows for easy access to the internal components, making inspection and repair work convenient. Additionally, the few parts present in butterfly valves result in reduced maintenance costs and downtime.

06/

Versatility
The versatility of butterfly valves is another advantage worth mentioning. These valves can be used in a wide range of industries, including petroleum, chemical, water treatment, HVAC, and food processing. They are suitable for both high and low-pressure applications, making them a preferred choice for many industries.

Types of Butterfly Valve
Wafer Full Lug Type Concentric Butterfly Valve
Casting Flanged P.S.B Globe Valve
Worm Wheel Flange Type Concentric Butterfly Valve
Wafer Type Concentric Butterfly Valve

Wafer Butterfly Valve: The wafer butterfly valve is the most common type of butterfly valve. It is designed to fit between two flanges in a pipe system. This type of valve is lightweight, compact, and less expensive compared to other types. It is ideal for low-pressure applications, and its simple design allows for easy installation and maintenance.

 

Lug Butterfly Valve: The lug butterfly valve has threaded inserts on both sides of the valve's body. These inserts allow the valve to be installed using bolts without needing nuts. This design makes it easier to install and remove the valve without having to disconnect the entire system. The lug butterfly valve is often used in applications that require frequent maintenance or where space is limited.

 

Double Offset Butterfly Valve: The double offset butterfly valve is designed to provide better sealing with reduced friction. It has an offset shaft, which means the axis of rotation is located behind the seal. This design reduces wear and tear on the seal, resulting in a longer lifespan and improved performance. Double offset butterfly valves are commonly used in high-pressure applications and industries such as oil and gas.

 

Triple Offset Butterfly Valve: The triple offset butterfly valve is a more advanced type of butterfly valve that offers excellent sealing performance and durability. It has three offsets: the first offset is the axis of rotation, the second offset is the position of the shaft relative to the seal, and the third offset is the cone shape of the sealing surface. This design allows for a bubble-tight seal, even under high-pressure conditions. Triple offset butterfly valves are commonly used in industries that require tight shut-off and reliable performance, such as power plants and chemical processing.

 

High-Performance Butterfly Valve: High-performance butterfly valves are designed to handle extreme conditions, including high pressures and temperatures. They are usually made of high-grade materials such as stainless steel or alloy, allowing them to withstand corrosive media and harsh environments. These valves are often used in applications where a tight shut-off is required, such as power plants, refineries, and petrochemical industries.

Application of Butterfly Valve

 

 

Regulating Fluid Flow: Butterfly valves are widely used for regulating fluids. As a regulating valve, this is done through the action of the actuator that communicates with the stem and disc assembly of the valve. The degree of angular opening translates to an exact amount of fluid that goes through the valve. Thus, the flow rate of the system is controlled through the actuators.Actuators can be manual or automatic. To control a regulating valve remotely, it must have a flow controller. This controller will automatically translate information to the valve mechanism to open or close based on the flow rate of the system.

 

Flow Isolation: Butterfly valves can be used for flow isolation because of their lightweight feature, easy manipulation and quarter-turn action.
However, when you use a butterfly valve as an isolation valve, you need to make sure that it would not negatively affect your system performance.That is why care should be taken when using this type of valve as an isolation valve. System losses should be accounted for in calculations to maintain a good system performance.

 

Backflow Prevention: Some food manufacturing processes require aggressive wash down procedures in which butterfly valves can be used for backflow prevention during this process. Backflow prevention is necessary as food processing plants should be clean and operate in extremely sanitary conditions.

 

As Throttling Valves: Butterfly valves are commonly used for regulating large fluid flows, including viscous slurries, but it should be noted that they are not a good choice for precision throttling.

 

For Constant Load Applications: Butterfly valves can handle large volumes of fluids but are sensitive to load changes in the system. This type of valve has a limited capacity in handling small load changes. Allowing a few millimeters opening can be equivalent to a large volume difference.

 

For Space-Restrictive Applications: One of the best features of butterfly valves is it is economical and space-saving. Systems with space restrictions can benefit from butterfly valves as compared with ball valves.

 

For Liquids and Gases: Butterfly valves can generally handle liquids and gases and even slurries, but not bulk solids. This is because dry bulk solids are abrasive and can erode the material (and seal) of the butterfly valve. Plus, butterfly valves are inefficient for delivering solids as its disc can create a restriction for the flow of solids.

How to Use the Butterfly Valve
 

 

oint 1:

Butterfly valves are widely used in various industries and play a crucial role in controlling the flow of fluids.The first step in the process of butterfly valve is the selection of the appropriate valve for a specific application. There are different types of butterfly valves available, such as wafer style, lug style, and double-flanged style. The selection depends on factors like the pressure and temperature of the fluid, the size of the valve, and the requirements of the system.

Point 2:

Once the suitable valve is selected, the installation process begins. It involves mounting the valve between two flanges using bolts and nuts. The valve is positioned in such a way that the disc is in the center of the pipe, allowing for smooth flow control.

Point 3:

After the installation, the butterfly valve is ready for operation. The valve can be manually operated or automated depending on the requirements. In manual operation, the operator uses a handle or a lever to control the position of the disc. This, in turn, regulates the flow of the fluid. In automated operation, the valve is equipped with an actuator, which can be pneumatic, electric, or hydraulic. The actuator controls the movement of the disc based on signals received from the control system.

Point 4:

During the operation of the butterfly valve, the disc rotates inside the valve body. When the valve is fully open, the disc is positioned parallel to the flow direction, allowing maximum flow. When the valve is closed, the disc is rotated perpendicular to the flow direction, blocking the flow completely.

Point 5:

Maintenance is an essential part of the process of butterfly valve. Regular inspection and lubrication are necessary to ensure the proper functioning of the valve. If any damage or wear is detected, it should be repaired or replaced promptly to avoid any potential leakage or performance issues.

Components of Butterfly Valve
 
Valve Body

Made from a tough and rigid material, the valve body houses and protects the disc and other internal components of the butterfly valve. It links the valve to the piping system and to the external operating mechanism that controls the disc.
Disc. The disc permits, regulates, and stops the flow of the fluid in the pipeline. Flow is controlled by the rotary motion of the disc. The discharge flow rate depends on the degree of disc opening.
When the disc is perpendicular to the flow’s cross-sectional area, the fluid is fully obstructed from flowing out of the valve. Otherwise, the fluid is permitted to flow through the space between the seat and the disc. It takes a 90° rotation from the closed position of the disc to allow full opening or closing of the valve. Flow is throttled when the disc is rotated less than 90°.

Stem

The stem is a shaft that connects the disc to the external operating mechanism. It is sealed by O-rings and bushings to prevent fluid leakage. The stem can be made from a one-piece shaft or two-piece (split-stem) shaft. The placement of the stem axis and its connection to the disc depends on the type of butterfly valve.
Seat or Sealing Ring: The valve seat for basic concentric butterfly valves is a ring that provides sealing between the disc edge and the valve body when it is in a closed position. Its sealing action is necessary to avoid leakage of any fluid to the discharge of the butterfly valve. Since the disc slides on the surface of the seat during valve opening, it must be made from a material with a low coefficient of friction.

Operating Mechanism

The external operating mechanism of a butterfly valve controls the fluid flow across the valve. It may be operated by manual rotation of the stem or by automatic actuation.
Manual operation of butterfly valves involves the application of torque to the lever or handwheel attached to the stem. Levers can set the valve into a closed, fully-opened, or partially-opened position. Larger butterfly valves are equipped with handwheels and gearboxes to increase torque and to aid in the opening and closing of the valve.

Triple Offset

Tripled offset has three eccentrics each of which is located differently in the valve. The eccentrics are placed in an offset position to form an offset conical profile creating a right angle cone.
Triple Offset Eccentrics

Bushing or Bearing

The quality and type of bushing determines the longevity of a butterfly valve. The best bushings are resistant to corrosion and wear and used for precision control, current limiting, and switching of chemicals, petrochemicals, chlorine, paper production, and electroplating. Bushings are made from a variety of materials with many types being self lubricating for enhanced performance of the butterfly valve.

Material of Butterfly Valve

 

 

Casting Flanged P.S.B Globe Valve

Stainless Steel

Stainless steel is a steel alloy that contains higher chromium content (10.5-30%), and trace amounts of nickel and molybdenum. Stainless steel is known for its high strength and toughness and corrosion and weather resistance. The corrosion resistance is attributed to its chromium content: a thin, inert chromium oxide layer is formed to prevent oxygen diffusion into the bulk of the material. When the surface is damaged or scratched, the chromium oxide layer reforms with the help of oxygen. This self-healing property disables rust formation. Resistance to pitting corrosion is attributed to molybdenum.

Carbon Steel

Carbon steel is a steel alloy that has a higher carbon content of up to 2.5%. It has good mechanical properties and can be used for applications in which there are no special requirements. The common carbon steel grades available for butterfly valves are ASTM A216 WCB (Welded Cast B-grade) and LCC (Low Carbon Content). WCB grade is used for high-temperature applications while the LCC is used at low temperatures. The valve body and disc of the butterfly valves are produced by a sand-casting process.

Hastelloy

Hastelloy is an alloy composed of nickel, chromium, and molybdenum; it was the first alloy formulated by Haynes International, Inc. It also has high strength, which is maintained at high temperatures, and it has excellent resistance to corrosion, cracking, and oxidizing and reducing agents. They are used to handle nitric, hydrochloric, and sulfuric acids at moderate temperatures.

Brass

Brass is an alloy of copper and zinc. It is a tough and durable material and can also withstand high temperatures. It is valued for its corrosion and biofouling properties, as well as for its anti-microbial properties that inhibit the growth of microbes and biofilms on its surface.
Brass butterfly valves are typically used in water purification, wastewater treatment, food, and pharmaceutical manufacturing. However, they are not applicable in the handling of water with high amounts of chlorine (e.g., seawater and swimming pool waters) because of the dezincification of brass by chlorine.

Nickel Alloys

Nickel alloys are also known for their resistance to corrosion, harsh environments, and high temperatures. They have better performance than stainless steel in highly corrosive environments. However, nickel butterfly valves have high density and are more expensive.

Titanium Alloys

Titanium alloys have a high strength-to-weight ratio. They are also known for corrosion and biofouling resistance and can be used in seawater environments and water treatment since they are non-toxic. However, titanium butterfly valves are also expensive.

Nickel Aluminum Bronze

Nickel Aluminum Bronze is a copper-based alloy that contains 10% aluminum, 5% nickel, and 5% iron. It is also known for its corrosion, antimicrobial, and biofouling properties. Nickel Aluminum Bronze butterfly valves are also used in seawater environments (e.g., offshore piping), water purification, and wastewater treatment.
Maintenance Tips for Butterfly Valve

 

 

 
 

Regular Inspection

Periodic inspection is crucial to identify any signs of wear, corrosion, or leakage. Inspect the valve body, disc, stem, and sealing components for any visible damage. Look for signs of buildup or clogging in the valve assembly as well.

 
 

Lubrication

Proper lubrication is essential to reduce friction and ensure smooth operation of the valve. Apply a suitable lubricant to the stem, disc, and sealing surfaces as recommended by the manufacturer. Regularly lubricate the valve to prevent excessive wear and tear.

 
 

Cleaning

Debris, sediments, or foreign particles can cause sticking or sealing issues in the valve. Clean the valve regularly to remove any buildup that can hinder the valve's performance. Use a mild solvent or cleaning agent to remove deposits from the valve components.

 
 

Sealing Inspection

Inspect the sealing components of the butterfly valve, including the seat and gasket, for any signs of deterioration. Replace any damaged or worn-out sealing elements to maintain a proper seal. A faulty seal can result in leakage or inefficient operation of the valve.

 
 

Valve Operation

Operate the valve periodically to prevent it from becoming stiff or seizing. Open and close the valve fully to ensure smooth movement and proper functioning. Avoid forcing or jamming the valve, as it can damage the internal components.

 
 

Bolts and Fasteners

Check the bolts and fasteners securing the valve to the pipeline or equipment. Ensure that they are tight and properly torqued. Loose or damaged bolts can cause misalignment or leakage, compromising the valve's efficiency.

 
 

Pressure Testing

Conduct regular pressure tests on the butterfly valve to assess its integrity. This will help identify any potential leaks or weaknesses in the valve assembly. Follow the manufacturer's guidelines when performing pressure tests.

 
 

Professional Maintenance

For complex or critical applications, it is advisable to seek professional maintenance services. Certified technicians can perform in-depth inspections, repairs, and necessary adjustments to ensure the valve's optimal performance and safety.

Our Factory
 

EO flange co.,Ltd. established in 1991 and in charge of commercial area with more than 20 years' experience in manufacturing, stocking, processing and exporting flanges. Our company annually produces 5,000 tons of finished flanges and pipe fittings made from stainless steel, carbon steel, alloy steel, dual-phase steel and many other materials. The products have been exported to 28 countries and areas, such as Japan, America, France, Germany, Italy, etc. With self-run import & export right, the company is capable of directly taking foreign customers' orders, producing standard flanges in accordance with ANSI, DIN, ASME and GOST domestic and international standards, and producing ring-type forgings, non-standard flanges and pipe fittings according to customers' drawings or samples.  

 

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Certifications
 

201708161657113859671

 

Frequently Asked Questions Butterfly Valve

Q: In what conditions a butterfly valve is recommended?

A: Butterfly valves are suitable for different applications because of their lightweight design and quick operation. Soft-seated butterfly valves are ideal for low-temperature, low-pressure applications, while metal-seated butterfly valves offer good sealing capabilities when dealing with severe fluid service.

Q: What is the most common use of butterfly valve?

A: Butterfly valves are used where space is limited. Unlike gate valves, butterfly valves can be used for throttling or regulating flow as well as in the full open and fully closed position. The pressure loss through a butterfly valve is small in comparison with the gate valve.

Q: What causes a butterfly valve to fail?

A: The most common causes of butterfly valve leakage include improper installation, damaged or worn-out components, inadequate sealing, corrosion and erosion, incorrect valve sizing, and manufacturing defects.

Q: Does it matter which way a butterfly valve is installed?

A: Valves can be installed in any orientation however it is best if it can be installed upright especially in bigger sizes to reduce load on the shaft caused by the actuator or gearbox trying to pull away. It is common for smaller butterfly valves to be mounted in various orientations eg water trucks.

Q: How do you tell if a butterfly valve is open or closed?

A: When the handle is parallel to the valve, it is closed, and when it is perpendicular to the valve, it is open. Butterfly valves are suited for use in garden irrigation, and they are also commonly used in space-restrictive applications. They have a slender design that makes them ideal for tight-fitting spaces.

Q: How much pressure can a butterfly valve handle?

A: High-performance valves tolerate pressure up to 1440 PSI and temps up to 1200°F. A cam-action occurs from the stem being behind the disc as it rubs against the during rotation at 90° for the first 10 degrees of opening, but also for the 10 degrees of closing.

Q: What is the pressure limit for a butterfly valve?

A: This standard covers rubber-seated butterfly valves suitable for a maximum steady-state fluid working pressure of 250 psig (1,723 kPa), a maximum steady-state differential pressure of 250 psi (1,723 kPa), and a maximum full open fluid velocity of 16 ft/sec (4.9 m/sec) based on nominal valve size.

Q: Can you repair a butterfly valve?

A: The answer is yes; both replacement and repair options are available depending on the extent of the damage, budget constraints, and long-term maintenance costs. Replacing a butterfly valve disc involves selecting a suitable replacement disc, removing the old disc, installing the new one, and testing its functionality.

Q: How many turns does it take to open a butterfly valve?

A: The handwheel or nut must be rotated through 7-50 turns (depending on model) to open or close the butterfly valve.

Q: Is there a flow on a butterfly valve?

A: The butterfly valves are bi-directional but do have a preferred flow direction. It's however strongly recommended to install the valves in the preferred flow direction, as it will extend the valve's life span and will also lower the operating torque.

Q: Can you lock a butterfly valve?

A: Butterfly valve lockout devices prevent the valve handle from being turned to open the valve and restore energy through the pipe. A padlock is required to ensure the lockout isn't removed by unauthorized personnel.

Q: Do butterfly valves restrict flow?

A: Butterfly valves work as throttling devices by controlling the flow of fluids through a circular disc or plate positioned in the path of the flow. The disc is mounted on a shaft that is rotated by a handle or actuator, allowing the disc to be positioned at different angles to the flow path.

Q: What is the flow direction of a butterfly valve?

A: When speaking of flow direction through a butterfly valve, the flow is commonly described as either toward the "seat side" or "non-seat side" of the valve, or toward the "flat side" or "dome side" of the disc

Q: How do you pressure test a butterfly valve?

A: To test a butterfly valve's sealing performance, the test medium should be introduced from the medium inflow end. Make sure the butterfly plate is opened, the other end closed, and inject the test medium at the pressure specified by your testing requirements.

Q: Can you throttle a butterfly valve?

A: Unlike gate valves, butterfly valves can be used for throttling or regulating flow as well as in the full open and fully closed position. The pressure loss through a butterfly valve is small in comparison with the gate valve.

Q: What is a seal ring on a butterfly valve?

A: The butterfly valve seal is an essential component for blocking all three potential leakage paths: the sealing of pipes, flanges and operating shafts, in shut-off valves, flap valves and disk valves.

Q: What is butterfly valve basics?

A: Butterfly valves are a family of quarter-turn rotational motion valves that are used in pipelines to shut-off flow. It is often said that butterfly valves can be used to regulate the flow. However, we do not recommend doing this, as it can damage the valve disk and have a negative effect on the sealing properties.

Q: Can you hot tap a butterfly valve?

A: The valve on a hot tap connection can be either a block valve or a control valve for the new connection, and must allow the coupon (section of pipeline wall cut out by the drilling machine) to be removed after the cutting operation. Suitable valves include a ball or gate valve, but not a plug or butterfly valve.

Q: Should a butterfly valve be vertical or horizontal?

A: The butterfly valve can be installed at any position (vertical, horizontal or tilt). Butterfly valve with big size operator may need bracket. Collide when transporting or storing the butterfly valve may cause butterfly valve reduce its sealing ability.

Q: Does butterfly valve prevent backflow?

A: The primary purpose of butterfly check valves, like all check valves, is to ensure unidirectional flow of fluids in a system. They prevent the backward flow or backflow of fluids, which is critical in many fluid systems to maintain efficiency, protect equipment, and avoid potential disasters.
If you're looking for quality butterfly valve with cheap price, welcome to place orders for with our professional manufacturers and suppliers in China. Customized service is also supported by our factory.