Figure 1: Ball valve sectional view
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A ball valve is a shut-off device that regulates the flow of a liquid or gas using a rotating ball with a hole. By turning the ball a quarter turn (90 degrees) around its axis, the valve either opens or closes, allowing the medium to pass through or blocking it. Ball valves are known for their long lifespan and provide dependable sealing throughout their use, even when left unused for extended periods. They are more resistant to contaminated media than most other valve types.
Certain types of ball valves are also employed as control valves. This use is less frequent due to the relatively limited precision in controlling flow rates compared to other control valve types. However, ball valves have some advantages in this regard. For instance, they maintain reliable sealing even when the media is dirty. Figure 1 illustrates a cross-section of a ball valve.
Learn about other types of valves in our valve fundamentals article.
Figure 2: Ball valve diagram: stem (A), o-rings (B), housing (C), ball (D), and seat (E).
It is important to know the five main ball valve parts to understand the working principle of a ball valve. The diagram of the ball valve in Figure 2 shows these five main components.
When the valve stem is turned a quarter-turn the bore is either open to the flow allowing media to flow through or closed to prevent media flow. A ball valve's circuit function, housing assembly, ball design, and operation types all impact its operation and are discussed below.
Ball valves are more popular as a shut-off valve than, for example, the gate valve. For a complete comparison, read our gate valve vs. ball valve article.
The valve may have two, three or even four ports (2-way, 3-way, or 4-way). The vast majority of ball valves are 2-way and manually operated with a lever. The lever is in line with the pipe when the valve is opened. In the closed position, the handle is perpendicular to the pipe. The ball valve flow direction is simply from the input to the output for a 2-way valve. Manually operated ball valves can be quickly closed and therefore there is a risk of water hammer with fast-flowing media. Some ball valves are fitted with a transmission. The 3-way valves have an L-shaped or T-shaped bore, which affects the circuit function (flow direction). This can be seen in Figure 3. As a result, various circuit functions can be achieved such as distributing or mixing flows. A 90-degree ball valve has two ports that are positioned at a 90-degree angle.
Figure 3: Example of a 3-way ball valve and the circuit functions for a T-bore and L-bore.
The assembly of the valve housing can be divided into three commonly used designs: one-piece, two-piece, and three-piece housings. The difference is how the valve is assembled and this affects the possibilities for maintenance or repair. The operation of the valves is the same in each embodiment.
Read our 1,2,3-piece ball valve article for more details on the construction and design of each type.
Forged ball valves are created by shaping the alloys and metals while they are still in their solid form. The metals and alloys are bent by heating or with industrial-sized tools that deliver compressive forces to bend the materials. Forged ball valves are better suited for industrial applications that require high temperatures, pressures, and other severe conditions. Materials like brass and stainless steel can be used to construct forged ball valves. During the manufacturing process, the metal (or alloy) is heated, compressed, bent, and shaped according to the ball valve design using a die forging machine.
The die helps mold the metal into a specific shape, while the machine applies sufficient pressure that forces the metal to get into the apt shape. For ball valves that are sized bigger, it is necessary to weld different components together. The valves can also be coated with specialized coatings based on specific needs.
The most common design is the "floating ball design." The ball is suspended in the media and held in place by two sealing rings. Some high-quality valves have a trunnion ball design. The ball is supported at the top and bottom to reduce the load on the valve seats.
The hole through the ball may have different profiles such as a full bore, reduced bore or V-shaped.
To learn more about making the right selection for your application, read our ball valve selection technical article.
The handle is connected to the valve stem (Figure 2 number 1) and is capable of turning the valve from the open or closed position (90 degrees). If installed correctly, the valve will be open when the handle is parallel to the pipe and closed when the handle is perpendicular to the pipe. Taking note of the handle direction is important to visually know if the ball valve is open or closed. There are additional ball valve handle types, like lockable handles or ball valve handwheels. These operate as their names suggest. If you have a bigger ball valve or need additional torque to open or close the valve, a ball valve handle extension may be required. If your handle breaks, is miss-placed or you are converting an automatic ball valve to a manual one, you can buy ball valve replacement handles.
Vented ball valves look almost the same as the standard 2-way ball valves when it comes to their design. The main difference is that the outlet port vents to the environment in the closed position. This is achieved by a small hole that is drilled in the ball and in the valve body. When the valve closes, the holes line up with the outlet port and release the pressure. This is especially useful in compressed air systems where depressurization provides a safer working environment. Intuitively these valves look like 2-way ball valves while in fact, they are 3/2-way due to the small borehole for venting.
Instead of a manual handle operation to turn the valve on or off, some valves can be fitted with an electric or pneumatic actuator as seen in Figure 4. They connect directly to the valve stem (Figure 2 number 1) and are capable of turning it a quarter turn. The most common flange connection between the valve and actuator is the ISO standard. Figure 4 shows an example of an ISO top ready to be connected to an actuator. By using an actuator, you can control your ball valve remotely or through a controller so that it can be used as an automatic shut-off. A spring-actuated ball valve, also called a spring-loaded valve or a spring return ball valve, uses a spring to open/close the valve in a power-off scenario and an actuator to then hold the ball valve in the on/off position. These are used for energy conservation applications or for fail-safe reasons.
Figure 4: Pneumatic ball valve (left), electric ball valve (middle), ISO-top ball valve (right).
There are several different ways to control an electric actuator:
Certain electric actuators can also provide modulation control, which will position the ball valve between 0-100% open/closed. For more information regarding automatic operation, read our article on installing electrically operated ball valves.
The most common housing materials are brass, stainless steel and PVC (PolyVinyl Chloride). The ball is usually made of chrome plated steel, chrome plated brass, stainless steel or PVC. The seats are often made of Teflon, but could also be made of other synthetic materials or metals. Read our chemical resistance of materials for more information.
Brass has the largest market share (Figure 5). Brass is an alloy of copper and zinc and has good mechanical properties. Brass valves are used for (drinking) water, gas, oil, air and many other media. Chloride solutions (e.g. seawater) or demineralized water may cause dezincification. Dezincification is a form of corrosion in which zinc is removed from the alloy. This creates a porous structure with a greatly decreased mechanical strength. A brass housing is ideal for an air ball valve or a ball valve for plumbing. View our manual 2-way brass ball valves or 3-way brass ball valves.
Figure 5: Brass ball valve.
Stainless steel is used for corrosive media and aggressive environments (Figure 6). They are therefore often used in seawater, swimming pools, osmosis installations, with high temperatures, and many chemicals. Most stainless steel is austenitic. Type 304 and 316 are the most common, 316 has the best corrosion resistance. 304 is sometimes referred to as 18/8 because of 18% chromium and 8% nickel. 316 has 18% chromium and 10% nickel (18/10). Stainless steel valves usually require a higher operating torque than for example brass or PVC valves. This must be taken into account when a stainless steel valve is operated by an electric or pneumatic actuator. View our manual 2-way stainless steel ball valves or 3-way stainless steel ball valves.
Figure 6: Stainless steel ball valve.
PVC often has a lower price (except for ISO-top valves) and is widely used in irrigation, water supply and drainage or corrosive media (Figure 7). PVC stands for polyvinyl chloride. PVC is resistant to most salt solutions, acids, bases, and organic solvents. PVC is not suitable for temperatures higher than 60 °C, and is also not resistant to aromatic and chlorinated hydrocarbons. PVC is not as strong as brass or stainless steel, therefore PVC ball valves have lower pressure rating. Read our article about PVC ball valves for more information about this type of valve.
Figure 7: PVC ball valve.
For a comparison between the uses of a ball valve and a butterfly valve, read our butterfly and ball valve comparison article.
Most valve seats are made of PTFE (Teflon). PTFE stands for PolyTetraFluorEthylene. This material has a very good chemical resistance and a high melting point (~327 °C). Besides that, the friction coefficient is extremely low. A small disadvantage of PTFE is that the material shows creep, which can cause a deterioration of the sealing over time. Besides that, PTFE has a rather high thermal expansion coefficient. A solution for this problem is to use a spring in order to apply constant pressure on the Teflon seal, like for example a cup spring. Other popular sealing materials are PTFE and Polyamide (Nylon). The harder the material of the valve seat is, the more difficult it is to maintain proper sealing. For some applications in which soft materials are not possible to use, for example with very high temperatures, metal or ceramic valve seats are used.
Figure 8: High-pressure ball valve.
As the name suggests, a high-pressure ball valve works under high fluid pressure, approximately 500-700 bars. When the valve size gets bigger, it reduces the pressure it can handle, and vice versa. These valves are highly durable and used in piping systems with connections at the same pressure load. Manual-type high-pressure ball valves can be operated by turning the lever 90 degrees. Motorized high-pressure ball valves are simulated through an electric signal for their operation. Materials like carbon steel and stainless steel 316 are used for the valve's construction. Duplex or other highly resilient materials should be used to construct valve parts like stem, ball, and seat rings. This helps withstand the valve's high-pressure ratings and the actuator's maximum allowable stem torque.
High-pressure ball valves are available in the following connection types:
High-pressure ball valves are used in those sectors where the fluid is stored in large quantities and used according to their requirements, like water parks, water distribution plants, and chemical industries.
Hydraulic ball valves are specially designed for hydraulic and heating systems due to their high operating pressure rating and hydraulic and heating oil resistance. These valves are made of either steel or stainless steel. Besides these materials, the seats also make hydraulic valves suitable for high operating pressure. The seats of these valves are made of polyoxymethylene (POM), which is suitable for high-pressure and low-temperature applications. The maximum operating pressure of hydraulic ball valves goes above 500 bar while the maximum temperature goes up to 80 °C.
Ball valves can be connected to pipes in several ways, making them versatile for various applications. These are their common connection types:
For certain applications, approvals are desired or required. Drinking water and gas are the most common. Choosing a certified ball valve, assures that the product meets important safety requirements.
These ball valves are suitable for drinking water applications and have a WRAS, KIWA or DVGW approval. If being used with a water holding tank, they often work in connection with a float switch to monitor water level. Additionally, the water ball valve shut off feature ensures a quick and secure means to stop water flow when necessary.
Figure 9: Common drinking water ball valve approvals (DVGW, KIWA, WRAS).
These ball valves are approved for gas appliances.
Figure 10: Common gas ball valve approvals (DVGW, GASTEC, EN-331).
A ball valve is open when the handle is in line with the pipe and closed when the valve is perpendicular to the pipe. It only needs to be rotated 90 degrees.
A ball valve is a shutoff valve that controls the flow of a liquid or gas by means of a rotary ball having a bore. They can be operated by a handle or automated with an electric or pneumatic actuator.
Screw the input and output of the ball valve into your threaded assembly. Ensure the handle is installed correctly (parallel is open) before installation.
Yes, a ball valve can fail. Common failure types are a damaged seal (valve won't seal 100%) or debris entering the valve (valve won't move).
A ball valve can be used both as a shut-off valve and as a control valve for both liquids and gasses. In the case of a control valve, the bore is usually made in a v-shape.
Forged ball valves are created by shaping the alloys and metals in their solid form. The metals and alloys are bent by heating or with industrial-sized tools that deliver compressive forces to bend the materials.
A ball valve is a type of shut-off valve used to manage the flow of liquids, gases, and vapors within a piping system. It operates by rotating a ball with a central bore that either permits or blocks flow. The ball is positioned between two seats and connected to an operating mechanism via a shaft. When the bore's cross-section is aligned perpendicularly to the flow direction, the valve blocks the fluid. Conversely, when the bore is aligned with the flow, the fluid passes through, with the flow rate determined by the exposed area of the bore.
Ball valves are a type of quarter-turn valve along with plug valves and butterfly valves. They can be operated manually or by using an actuator. The simplest operation of a ball valve is through the use of a wrench or a lever manually turned by an operator. Torque is applied to rotate the lever arm by 900 by either clockwise or counterclockwise to open or close the valve. If the lever arm is parallel to the pipe, it indicates that the valve is open. If the lever arm is perpendicular to the pipe, it indicates that the valve is closed.
Ball valves are available in a range of designs and features to meet diverse industrial requirements. The standards and specifications for these valves can differ based on the specific industry in which they are used.
The essential components of a ball valve are as follows:
The valve housing, or body, encloses all internal components of the ball valve. It provides a secure, sealed environment for the ball, ensuring accurate control of fluid flow through the valve. Typically, the housing includes inlet and outlet ports for pipe connections. It is constructed from durable materials like metal, thermoplastic, or thermoplastic-lined metal to safeguard the internal parts, guaranteeing the valve's longevity and reliability in various industrial settings.
The ball within a ball valve is a sphere with a central hole known as the bore. The bore serves as the passage for fluid flow when it aligns with the valve's flow path. If the bore is perpendicular to the flow direction, it restricts the flow. Ball valves may feature either solid or hollow balls. A solid ball maintains a consistent opening diameter, promoting smooth and constant fluid flow. Conversely, a hollow ball, with its internal cavity, allows for higher flow rates but can create turbulence and increased velocities. Hollow balls are typically lighter and more cost-effective than solid ones.
The shaft connects the ball to the control mechanism, enabling rotation of the ball. This rotation aligns the ball with the flow path to allow fluid passage or positions it perpendicular to block the flow. The shaft includes seals like O-rings and packing rings to prevent fluid leakage around the shaft. It must be robust enough to handle the system's pressure and temperature conditions. The shaft can be manually operated via a lever or handwheel, or it may be actuated electrically, pneumatically, or hydraulically.
The bonnet extends from the valve housing and encases the shaft and its packing, especially in high-pressure and high-temperature applications. It may be welded or bolted to the body and is typically constructed from sturdy metal. The bonnet provides a cover for the shaft connection to the external control mechanism and can be either removable or integral to the valve body, depending on the design.
Ball valves have two seats, usually made from soft materials such as PTFE (Teflon) or elastomers. These seats create a tight seal around the ball when the valve is closed, preventing leaks by forming a barrier between the ball and the valve body. The upstream seat seals against pressure, while the downstream seat prevents leakage to the atmosphere.
Electric actuators, or motorized actuators, enable remote control of ball valves and are ideal for situations where manual operation isn't feasible. These actuators can be designed as either quarter-turn or multi-turn units. Quarter-turn actuators are suited for valves that can be fully opened or closed, while multi-turn actuators provide multiple rotations for more nuanced control.
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At the core of an electric actuator is its electric motor, which drives a gear system available in various torque ranges. This gear drive connects to an output drive that operates the valve. All components are housed in a sealed, waterproof enclosure. Electric actuators are remotely controlled and can include features such as adjustable cycle times, duty cycles, and even network or databus connectivity for enhanced functionality.
In addition to electric actuators, pneumatic actuators are available and perform similar functions. These rely on an air supply, which can limit their applicability compared to electric actuators. While electric actuators tend to be more expensive, they offer greater versatility and can be adapted to a wider range of applications.
Motorized ball valves provide automated control by using an electric motor to open or close the valve. These valves feature an electric actuator mounted to the valve body, which rotates 90° to control the valve's position. The actuator responds to electrical signals that dictate whether the valve should be opened or closed.
For applications requiring precise valve positioning based on flow conditions, a digital position sensor may be employed. This sensor, coupled with a microprocessor, compares the actual valve position with the desired position using feedback from an output system. The actuator adjusts accordingly to align with the input signals.
Motorized ball valves are commonly used in remote locations to control the flow of materials. They are designed to accommodate various applications and can be located at significant distances from the control point. These valves offer a practical and efficient solution for valve control, significantly reducing labor and enhancing material handling processes.
Pneumatic actuators function similarly to electric actuators but use compressed air to control ball valves. These actuators feature a housing with horizontal pistons connected to a rack and pinion mechanism, which converts the pistons' linear motion into rotary motion. The pistons are driven by compressed air, making the system straightforward, reliable, and more cost-effective compared to electric actuators.
Like electric actuator systems, pneumatic actuators have specialized mounts for easy valve installation. They operate by receiving controlled bursts of air. A solenoid, mounted on the actuator and connected via an air line, is energized by an electric current. This current moves a plunger that opens ports on the actuator, allowing air to actuate the valve.
Air actuated ball valves come with features similar to those found in electric actuated valves, including positioners, limit switches, gear operations, and speed control. While pneumatic actuators are robust and dependable, they require proximity to an air supply, making them suitable for environments where access to compressed air is readily available.
Ball valves can be categorized based on their housing assembly, ball design, and bore profile.
A one-piece ball valve features a single, cast body that encases all internal components, minimizing the risk of fluid leakage. These valves are the most cost-effective and typically have a reduced bore. Welded one-piece ball valves are common but are not designed for disassembly, making them unsuitable for applications where cleaning or repair might be necessary. They are best used in environments where particle accumulation is minimal and sanitation is not a primary concern. In contrast, screwed one-piece ball valves can be cleaned, serviced, and repaired, though disassembly requires specialized tools.
Split body ball valves are designed with their bodies assembled around the ball. These valves can be categorized as either two-piece or three-piece configurations:
A two-piece ball valve features a housing divided into two sections that are assembled together. One section houses the ball and provides a connection at one end, while the other section contains the internal components and connects at the opposite end. This design is the most prevalent among ball valves. Although the two sections can be separated for cleaning, maintenance, and inspection, this process requires removing the valve from the pipe.
A three-piece ball valve comprises a housing that encloses the internal components, with the housing sections connected and secured by bolts at each end. These ends are typically threaded or welded to the main pipe.
Three-piece ball valves are ideal for applications requiring easy cleaning and maintenance. The design allows for the replacement of seats and seals without removing the entire valve from the pipeline, which is particularly beneficial in industries such as food and beverage and pharmaceuticals, where cleanliness and product safety are critical.
A top entry ball valve provides access to its internal components by removing the bonnet from the top of the valve. This design facilitates in-line maintenance activities'such as disassembly, cleaning, inspection, and repair'without the need to remove the valve from the pipeline.
The floating ball is a prevalent design used in ball valves. In this design, the ball is suspended within the valve and can move laterally when the valve is closed. It is positioned between two seats that secure and support the ball. The ball is connected to the shaft at one end via a slot, while the other end remains free. When the valve is open, the shaft's connection at the top of the ball keeps it from moving laterally.
Sealing in a floating ball valve relies solely on fluid pressure. When the valve operates, the inlet fluid pressure pushes the ball against the outlet seat, preventing any leakage from the valve body. The fluid pressure exerted on the ball and seats is higher when the valve is closed.
Floating ball valves are known for their simple design and are typically used in smaller diameters for handling liquids and gases under low to moderate pressures. Their application is constrained by the pressure tolerance of the seats. At higher pressures, the seats may deform due to the force exerted by the ball, potentially compromising the valve's sealing ability at lower pressures. Additionally, the torque required to turn the shaft is influenced by the force needed to overcome the fluid pressure acting on the ball and seats.
In a trunnion ball valve, the ball is supported by an additional shaft at the bottom known as the trunnion. This design stabilizes the ball and restricts its movement to the axis of the valve. The ball's movement is controlled by the rotation of the valve shaft. Trunnion ball valves also include spring-loaded seats. The inlet fluid pressure compresses the springs towards the ball, creating a secure seal.
Trunnion ball valves come in a range of sizes from small to large but are generally more costly than floating ball valves. They are well-suited for high-pressure applications because they efficiently handle a wide range of pressures. The fluid pressure is distributed to both the trunnion and the seat springs, resulting in lower operating torque and enabling the use of smaller actuators.
A vented ball valve operates similarly to a standard ball valve, with the key difference being that the vented ball has small orifices drilled into its side. When the valve is closed, these orifices align with the outlet side of the valve. The purpose of these drilled holes is to release trapped gases that can accumulate and build up internal pressure. This feature helps prevent leaks, valve failure, and potential explosions.
Vented ball valves are commonly used in applications involving compressed air systems, cryogenic processing, and the handling of volatile liquids. They are sometimes referred to as "cryogenic valves" due to their effectiveness in cryogenic environments.
A full bore ball valve features a bore diameter that matches the pipe diameter, ensuring that the flow area remains consistent. This design results in minimal flow resistance and low frictional losses, which translates to a lower pressure drop. Such low pressure drop reduces the difficulty of pumping within the system. However, because the bore diameter must match the pipe size, full bore valves require larger ball sizes and housings, making them more expensive than reduced bore valves.
Full bore ball valves are also easier to maintain and clean. In pipeline systems, a process called pigging is used for maintenance and inspection. This involves using spherical or cylindrical devices known as pigs to travel through the pipes, detecting and removing build-ups without disrupting the fluid flow. This process is facilitated by the larger diameter of full bore ball valves.
Additionally, full bore ball valves are well-suited for handling liquids with mixed solids. They help prevent the accumulation of particles that could otherwise cause blockages or separation of the mixture as it flows through the system.
A reduced bore ball valve features a bore diameter that is smaller than the pipe diameter by one pipe size. The exact reduction is specified based on the agreement between the manufacturer and the customer. This design narrows the flow area at the outlet, which introduces frictional losses and results in a pressure drop. As the flow area decreases, the velocity of the fluid increases to maintain the same flow rate.
Reduced bore ball valves are more commonly used than full bore ball valves, particularly in applications where flow rate and turbulence are not critical concerns, and where particle build-up is unlikely. They are generally less expensive than full bore valves due to the smaller ball size and housing required. Additionally, reduced bore ball valves typically experience a smaller pressure drop compared to other types of valves.
A segmented ball valve features a V-shaped notch on the ball, which provides precise flow rate control based on the ball's rotation. This design also ensures effective shut-off capability. The flow characteristics of a segmented ball valve are designed to approximate an equal percentage flow curve, meaning that the flow rate increases exponentially as the ball nears the fully open position.
A cavity-filled ball valve features a seat design that fills the gap between the ball and the valve body, preventing the accumulation of trapped media or particles that could lead to contamination or blockages. This design makes cavity-filled ball valves easier to clean and maintain.
These valves are particularly valuable in industries where hygiene is critical, such as the food, pharmaceutical, and bioprocessing sectors. They are well-suited for handling solid-liquid mixtures, such as slurries, due to their effective design.
Multi-port ball valves are designed to manage multiple fluid streams, allowing for diversion, combination, splitting, or shutting off of flows. They achieve this through a ball with either an L-shaped or T-shaped bore. While these valves can direct flow from a single inlet to multiple outlets, they do not regulate the flow rates to each outlet stream. Multi-port ball valves are versatile in combining several streams into one or redirecting flow as needed. The schematic diagram below illustrates the various flow configurations for L-shaped and T-shaped multi-port ball valves.
Three-way ball valves feature three ports for capturing and directing fluid flow. The valve's core component is a metal ball with internal passages that regulate the flow of fluid or gas. As the fluid enters the valve, a mechanism rotates the ball to direct the flow through the desired port. Three-way ball valves are available in designs with either two outlet ports and one inlet port or two inlet ports and one outlet port.
These valves can be configured in L or T shapes and are capable of various functions such as switching flow direction, mixing flows, diverting streams, and stopping flow while allowing other flows to continue. When used for mixing, the valve allows fluid to enter from multiple directions and combine within the valve body.
Three-way ball valves are equipped with three ports for controlling fluid flow. They feature a central metal ball with internal passages designed to manage the direction of the fluid. As fluid or gas flows into the valve, a rotating mechanism adjusts the ball to direct the flow through the appropriate port. Three-way ball valves come in configurations with either two outlet ports and one inlet port or two inlet ports and one outlet port.
Similar to multi-port valves, three-way ball valves can be configured in either an L-shaped or T-shaped arrangement. They are versatile and can perform various functions such as switching the direction of flow, mixing different flows, diverting flow, and blocking flow from multiple directions. When mixing materials, the valve allows fluids to enter from multiple directions and blend within the valve body.
Sanitary ball valves are designed to adhere to stringent cleanliness and hygiene standards, making them suitable for applications in the food, beverage, medical, and pharmaceutical industries. These valves are engineered to meet health and safety regulations that require strict control over microbial contamination, ensuring the purity of substances during processing.
The body of sanitary ball valves is typically constructed from series 304 or series 316 stainless steel. Series 304 is commonly used in hospitals and food processing due to its smooth surface and durability, which allows for repeated cleaning without significant wear. Sanitary ball valves are designed for frequent assembly, disassembly, cleaning, and reassembly to prevent microbial growth and contamination.
These valves are engineered to mitigate risks associated with biological, chemical, or physical hazards. To ensure easy cleaning and avoid contamination, sanitary ball valves avoid threaded connections. Instead, they use seals, O-rings, and seats made from inert, abrasion-resistant materials such as polytetrafluoroethylene (PTFE or Teflon).
Sanitary ball valves address the typical issue of dead spots between the ball and the seat where bacteria can grow by employing cavity-filled ball seats. These seats fill the dead space with PTFE, reducing the risk of contamination. Additionally, the surfaces of sanitary ball valves are polished to a high finish with roughness average (Ra) values ranging from 8 to 32 to eliminate peaks and imperfections that could harbor contaminants.
Ball valves are typically made from a range of materials for both the ball and the housing, including:
Brass, an alloy primarily composed of copper and zinc, is easily recognized by its dull yellowish to reddish hue, which varies based on zinc content. It is a popular choice for ball valves due to its strength, durability, and ability to handle high temperatures and pressures. Brass also boasts antimicrobial properties thanks to its copper content, which helps prevent microbial growth on its surface. It offers good resistance to chemicals, corrosion, and biofouling. However, brass can be susceptible to dezincification when exposed to high chlorine levels, which can lead to the loss of zinc and weaken the alloy's structure.
Brass ball valves are not difficult to fabricate because of their malleability, and they are also easy to cast and weld. They are lighter and cheaper than steel ball valves. They are also easy to assemble in the piping system. Common applications of brass ball valves are in food, chemical, and oil and gas processing, and in conveying gaseous fluids. It is also safe to use in the delivery of potable drinking water.
Stainless steel is a high-strength alloy known for its excellent corrosion resistance, achieved through its high chromium content and, in many cases, nickel. It maintains its strength and durability even under high temperatures and pressures, making it a reliable material for demanding applications.
Common grades of stainless steel used in ball valves are 304 and 316. Type 304 stainless steel contains 18% chromium and 8% nickel, while 316 stainless steel includes 18% chromium, 10% nickel, and trace amounts of molybdenum. The addition of molybdenum in 316 stainless steel enhances its resistance to chlorides and other corrosive agents.
Stainless steel ball valves are particularly advantageous in several applications. They are commonly used in swimming pools to manage chlorinated water, in industrial settings such as desalination and petroleum refining where they handle corrosive chemicals at high temperatures and pressures, and in breweries for processing wort, a reactive liquid produced during mashing.
PVC (Polyvinyl Chloride) is a tough, rigid plastic material known for its durability and affordability compared to brass and stainless steel. While it generally has lower strength and a lower temperature and pressure rating (up to 150 psi and 140°F, respectively), PVC is resistant to corrosion and most acids, bases, and salt solutions. However, it is not resistant to aromatic compounds and hydrocarbons. PVC ball valves are commonly used in plumbing, irrigation, and water distribution systems.
Chlorinated PVC (CPVC) is a modified form of PVC that has been chlorinated through a free radical reaction initiated by UV light. This chlorination enhances CPVC's temperature resistance, allowing CPVC ball valves to handle temperatures up to 200°F. CPVC ball valves are suitable for applications requiring higher temperature tolerance than standard PVC.
Polypropylene (PP) is a versatile, resilient, and lightweight thermoplastic derived from propylene monomer. It is known for its high resistance to many acids and bases, although its compatibility with organic compounds and solvents is somewhat limited. The material's chemical resistance diminishes at elevated temperatures, with a maximum service temperature of 82°C. PP ball valves are effective for managing the flow of various fluids, including those with different viscosities. These valves are commonly utilized in industries such as sugar production, fertilizers, chemicals, and paper manufacturing.
Glass-fiber-reinforced polypropylene (GFPP) incorporates glass fibers into polypropylene to enhance its dimensional stability, rigidity, and chemical resistance, while also reducing its thermal expansion coefficient. With a 40% glass fiber composition, the heat deflection temperature can reach up to 150°C at 264 psi. The addition of glass fibers improves the material's cost-effectiveness and enables it to withstand more demanding and severe applications.
PVDF (Polyvinylidene Fluoride) is a high-purity, robust thermoplastic fluoropolymer with a high molecular weight. It is produced through the free-radical polymerization of vinylidene fluoride gas. Additionally, PVDF is known for its resistance to abrasion.
This polymer offers exceptional chemical resistance, making it ideal for handling aggressive liquids and gases such as sulfuric acid, hydrochloric acid, nitric acid, hydrocarbons, fuels, and both aromatic and aliphatic halogenated solvents. It is widely used in ball valves across various industries, including water purification, wastewater treatment, and food and pharmaceutical processing, due to its resistance to biofouling and microbial film growth. PVDF is also stable when exposed to sunlight and UV radiation. The maximum operational temperature for PVDF is approximately 115°C.
Polyethylene (PE) is a versatile, resilient, and lightweight thermoplastic that is the most widely used plastic. It exhibits compatibility with a range of substances, including strong acids and bases, as well as some organic compounds like oils and alcohols. As PE's crystallinity and density increase, its chemical resistance improves. PE ball valves are utilized in various manufacturing processes and are also effective in water purification and wastewater treatment. The maximum operational temperature for PE is about 60°C.
The seat in a valve is typically made from elastomeric materials, plastics, or metals to ensure a secure seal with the ball. An ideal seat material should also exhibit the following qualities:
Common materials used for ball valve seats include:
Metal-seated ball valves are capable of enduring higher temperatures and hydraulic pressures. They are also more resistant to abrasive and corrosive fluids.
Ball valves provide numerous advantages in a range of applications, thanks to their design and operational features. Key benefits of using ball valves include:
Users should be aware of certain limitations to maintain the optimal performance of ball valves:
Standard ball valves may be used in throttling low pressure gases. Segmented ball valves may be used in limited throttling applications.
However, advanced ball valves with modified designs or seats made from engineered materials that are suitable for throttling applications are commercially available.
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