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A ball valve is a globe valve that controls the flow of a liquid or gas by means of a rotating ball with an internal bore. By rotating the ball a quarter turn (90 degrees) about its axis, the medium can flow through or be blocked. They are characterized by their long service life, providing a reliable seal for the life of the valve, even if the valve is not used for a long time. For this reason, they are preferred as globe valves over gate valves.
In addition, they are more resistant to contaminated media than most other types of valves. In special versions, ball valves can also be used as control valves. This application is less common because of their relatively limited accuracy in controlling flow compared to other types of control valves. However, the valve has some advantages here as well. For example, it ensures a reliable seal even in dirty media.
Standard ball valves consist of a housing, a seat, a ball and a lever for ball rotation. They include valves with two, three, and four ports and can be either female or male threaded or a combination of both. Threaded valves are the most common and come in many varieties: certified for specific media or applications, mini-ball valves, angled ball valves, ISO-top ball valves, with integrated filters or bleed points, etc. They are available in a wide range of options and operate in a wide range of pressures and temperatures. (Ball Valves vs. Butterfly Valves) (Gate valve vs. ball valve)
Hydraulic ball valves are specially designed for hydraulic and heating systems because of their high working pressure rating and resistance to hydraulic and heating oil. These valves are made of steel or stainless steel. In addition to these materials, the seats also make the hydraulic valves suitable for high working pressures. The seats of these valves are made of polyformaldehyde (POM) and are suitable for high pressure and low temperature applications. The maximum working pressure of hydraulic ball valves exceeds 500 bar, while the maximum temperature can reach 80°C.
Flanged ball valves are characterized by the way they are connected. Their ports are connected to the piping system by means of flanges, which are usually designed according to certain standards. These valves provide high flow rates because they usually have a full bore design. When selecting a flanged ball valve, in addition to the pressure rating, you must also check the flange compression rating, which indicates the highest pressure this connection type can withstand. These ball valves are designed with two, three or four ports, and they can be approved for specific media, having an ISO-top and everything else a standard quarter-turn valve can have. They are usually made of stainless steel, steel or cast iron.
Vented ball valves are virtually identical in design to standard two-way ball valves. The main difference is that in the closed position, the outlet port vents to the environment. This is accomplished by drilling a small hole in the ball and valve body. When the valve is closed, the small hole aligns with the outlet port and releases pressure. This is particularly useful in compressed air systems because the reduced pressure provides a safer working environment. Intuitively, these valves look like two-way ball valves when in fact they are 3/2-way because of the small hole for bleeding.
To understand how the ball valve works, it is important to know the 5 main components and the 2 different types of operation of the ball valve. These 5 main components can be seen in the ball valve diagram in Figure 2. The stem is connected to the ball and can be operated manually or automatically (electric or pneumatic). The ball is supported and sealed by a ball seat with an O-ring around the stem. All of this is inside the valve housing. The ball has a hole through it. When the stem is turned a quarter turn, the hole either opens to the flow of water, allowing the media to flow through, or closes, preventing the media from flowing through. The valve's circuit function, housing assembly, ball design, and type of operation all affect the operation of the ball valve.
Valves may have two, three or even four ports (2-way, 3-way or 4-way). The vast majority of ball valves are two-way and are manually operated with a lever. When the valve is open, the lever is aligned with the pipe. In the closed position, the handle is perpendicular to the pipe. For 2-way valves, the flow direction of the ball valve is simply from input to output. Manually operated ball valves can be closed quickly, so there is a risk of water hammer in fast flowing media. Some ball valves are equipped with actuators. Three-way valves have an L-shaped or T-shaped orifice, which affects the circuit function (flow direction). This can be seen in Figure 3. Thus, various circuit functions can be realized, such as distribution or mixed flow.
The assembly of the valve body can be divided into three common designs: one-piece, two-piece and three-piece bodies. The difference lies in the way the valve is assembled, which affects the possibility of maintenance or repair. The operation of the valve is the same in each of these implementations.
One-piece type. This is the cheapest variant. The two parts that enclose the ball are pressed or welded. The valve cannot be opened for cleaning or maintenance. This type is generally used for low-demand applications.
Two-piece type. Two-piece valves can be disassembled for cleaning, maintenance and inspection. Typically, the parts are connected by threads. The valve must be completely removed from the piping to separate the two parts.
Three-piece. More expensive valves usually come in three pieces. These parts are typically clamped together by bolted connections. The advantage of this implementation is that the valve can be serviced without removing the entire valve from the pipeline.
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 use a trunnion ball design. The ball is supported at the top and bottom to reduce the load on the valve seat.
Floating. Most ball valves have a floating ball. The ball is supported by the seat.
Trunnion type. Valves with large diameters and high working pressures (e.g. DN > 100 mm and 30 bar) are usually trunnion type. The ball is supported on the bottom and top to reduce the load on the seat ring. The operating torque of trunnion type valves is generally lower.
The bore through the ball may have different shapes, such as full, reduced or V-shaped.
Reduced orifice. Most ball valves have a reduced orifice. As a result, the valve introduces frictional losses in the system. These losses are still relatively small compared to other types of valves. One-piece ball valves are almost always reduced bore.
Full bore. A full bore valve has the same bore diameter as the pipe. The advantage is that there are no additional frictional losses and the system is mechanically easier to clean (pigging). The disadvantage is that the ball and housing are larger than a standard small bore quarter turn valve. As a result, the cost is slightly higher, and for many applications this is not necessary. They are also referred to as full port ball valves.
V-shape. The hole in the ball or seat has a "V" shaped profile. As a result, the desired flow rate can be more precisely controlled by rotating the ball. By optimizing the profile, the linear flow characteristics can be approached.
The handle is attached to the stem and is capable of turning the valve from the open or closed position (90 degrees). If installed correctly, the valve will be opened when the handle is parallel to the pipe and closed when the handle is perpendicular to the pipe. It is important to note the direction of the handle to visually know if the valve is open or closed. There are other ball valve handle types, such as lockable handles or ball valve handwheels. These operate as their name implies. If you have a larger 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 misaligned, or you are converting an automatic ball valve to a manual ball valve, you can purchase a replacement ball valve handle.
Some valves can be fitted with an electric or pneumatic actuator that is used to open or close the valve, rather than being operated by a manual handle. They are attached directly to the valve stem and are capable of turning it a quarter turn. The most common flange connection between the valve and the actuator is the ISO 5211 standard. An example of an ISO 5211 top ready connection to an actuator is shown. By using an actuator, you can control your ball valve remotely, or through a controller so that it can act as an automatic shutoff. Spring-actuated ball valves, also called spring-loaded, use a spring to open/close the valve in the event of a power failure and then use an actuator to hold it in the open/closed position. This type of valve is used for energy saving applications or for fail-safe reasons.
The 2-point control (also called an on-off or on-off circuit) uses a control wire in addition to the power wire. Once the control wire is energized, the valve is energized to open. If the control wire is not energized, the valve closes (by electricity or a spring).
The three-point control uses two control wires: one for rotating the ball counterclockwise and one for rotating the ball clockwise. Depending on the application, the most suitable control can be selected.
Some electric actuators can also provide modulating control to position the ball valve between 0 and 100% open/closed.
The most common housing materials are brass, stainless steel and PVC (polyvinyl chloride). The ball body is usually made of chrome-plated steel, chrome-plated brass, stainless steel, or PVC. Seats are usually made of Teflon, but can also be made of other synthetic materials or metals.
Brass has the largest market share. Brass is an alloy of copper and zinc with good mechanical properties. Brass valves are used for (potable water), natural gas, oil, air and many other media. Dezincification may result from chloride solutions (e.g. seawater) or demineralized water. Dezincification is a form of corrosion in which zinc is removed from the alloy. This creates a porous structure that greatly reduces mechanical strength. Brass housings are ideal for air ball valves.
Stainless steel can be used in corrosive media and aggressive environments. Therefore, they are often used in seawater, swimming pools, osmosis installations where there are high temperatures and many chemicals. Most stainless steels are austenitic. 304 and 316 types are the most common, with 316 having the best corrosion resistance. 304 is sometimes called 18/8 because there is 18% chromium and 8% nickel. 316 has 18% chromium and 10% nickel (18/10). Stainless steel valves typically require a higher operating torque than brass or PVC valves. This must be taken into account when stainless steel valves are operated by electric or pneumatic actuators.
PVC is usually less expensive (except for ISO-top valves) and is widely used for irrigation, water supply and drainage or corrosive media. pvc stands for polyvinyl chloride. pvc is resistant to most salt solutions, acids, bases and organic solvents. pvc is not suitable for temperatures above 60°C and is not resistant to aromatic and chlorinated hydrocarbons.
| Material | Advantages | Disadvantages |
| Brass | Durable, suitable for most applications | Sensitive to dezincification |
| Stainless steel | Very abrasive resistant, inert, corrosion resistant | Higher price, often more torque needed to rotate the ball |
| PVC | Cost-effective, not prone to corrosion | Shorter lifetime, limited pressure and temperature ranges |
Most valve seats are made of PTFE (Teflon). PTFE stands for polytetrafluoroethylene. This material has very good chemical resistance and a high melting point (~327°C). In addition to this, its coefficient of friction is extremely low. A small disadvantage of PTFE is that this material is subject to creep, which can lead to loss of sealing properties over time. In addition, the coefficient of thermal expansion of PTFE is quite high. A solution to this problem is to use a spring in order to apply a constant pressure to the PTFE seal, such as a cup spring. Other popular sealing materials are the mandatory PTFE and polyamide (nylon). The harder the material of the valve seat, the more difficult it is to maintain a proper seal. For applications where soft materials are not possible, for example at very high temperatures, metal or ceramic seats can be used.
For certain applications, approvals are required or requested. Potable water and gases are the most common. Choosing an approved ball valve will ensure that the product meets important safety requirements.
These ball valves are suitable for potable water applications and have WRAS, KIWA or DVGW approvals. If used with a water storage tank they usually work in conjunction with a float switch to monitor the water level.
These ball valves are approved for use in gas appliances.
When does the ball valve open?
Ball valves are open when the handle is in line with the pipe, and closed when the valve is perpendicular to the pipe. They only need to be rotated 90 degrees.
What is a ball valve?
A ball valve is a globe valve that controls the flow of a liquid or gas by means of a rotating ball with an internal bore. They can be operated by a handle, or automatically by an electric or pneumatic actuator.
How do I install a ball valve?
Screw the input and output sides of the ball valve onto your threaded assembly. Make sure the handles are installed correctly (open in parallel) before installation.
Can a ball valve fail?
Yes, ball valves can fail. Common types of failures are damaged seals (valve does not seal 100%) or debris entering the valve (valve does not move).
What can ball valves be used for?
Ball valves can be used as both globe valves and control valves for liquids and gases. In the case of control valves, the orifice diameter is usually around 1.5 m.
What is a ball valve used for?
Ball valves are the most commonly used fluid shut-off valves in onshore and offshore upstream oil and gas production facilities. They are also used to fuel gas systems to furnaces. Plug valves have the following advantages: High pressure resistance.
What are the advantages of ball valves?
The biggest advantage of the ball valve is that the throttling characteristic is poor, which can easily lead to corrosion of the ball valve seat. They offer leak proofing services. They open and close quickly. Ball valves have multi-way design flexibility.
What is a ball valve in a pipeline?
Ball valves use a rotating ball with a hole and stem. When the handle attached to the valve stem is turned, it rotates the ball to open or close the valve. ...the valve opens when the handle is parallel to the pipe and closes when the handle is perpendicular to the pipe.
Why do ball valves fail?
A variety of factors can cause ball valve failure, including poor design (chemical compatibility, pressure/flow ratings, etc.), incorrect installation, and/or improper operation.
Which industries use ball valves?
If you are an oil or gas engineer, you know that ball valves are a very important component in a piping system. They are used for a variety of purposes throughout the oil and gas industry. For upstream applications, they control the flow of oil. For midstream, they protect equipment by controlling the flow of natural gas and oil.
What are the disadvantages of ball valves?
Wear: When used to regulate the wrong type of fluid, such as mud, the ball valve can become stuck in place and become stuck due to entrapment of suspended particles. This could cause the valve to wear, damage or seize.
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