Figure 1: Ball valve sectional view
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A ball valve is a shut-off valve that controls the flow of a liquid or gas by means of a rotary ball having a bore. By rotating the ball a quarter turn (90 degrees) around its axis, the valve is opened or closed and the medium can flow through or is blocked, respectively. Ball valves are characterized by a long service life and provide reliable sealing over the life span, even when the valve is not in use for a long time. They are more resistant to contaminated media than most other types of valves.
Certain versions of ball valves are also used as control valves. This application is less common due to the relatively limited accuracy of controlling the flow rate compared with other types of control valves. However, ball valves offer some advantages here. For example, they ensure reliable sealing, even if the media is dirty. Figure 1 shows a sectional view of a ball valve.
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.
For more high pressure on-off ball valveinformation, please contact us. We will provide professional answers.
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.
Valves are available with a wide variety of valve bodies in various styles, materials, connections and sizes. The most common types are ball valves, which can be of high and low pressure, depending on the application. Utilizing Oliver's unique design's we are able to produce these in either full or reduced bore, threaded or flanged, in a range of materials suitable for a wide range of demanding isolation applications and media.
As opposed to the Oliver low-pressure ball valves, the high-pressure ball valves are typically used to withstand high operating pressures and they keep streams of fluid under control whilst safely isolating or allowing the system fluid to pass through.
At Oliver Valves, we are one of the worlds leading manufacturers of instrumentation valves; we can implement solutions thanks to our history of cutting-edge control technology in the industry. Before looking at the difference between High-Pressure and Low-Pressure Ball Valves, we must ask ourselves, what is a Ball Valve?
The Oliver Ball valves operate in a quarter turn to action, which provides a quick opening & closing giving whilst providing a zero leakage bubble-tight shutoff; when fully closed. When open a ball valve creates little turbulence or resistance to flow, due to its smooth through bore. The valve stem rotates a ball that contains an opening; the ball opening can be positioned in the fully open or fully closed position. It must not be used to throttle flow as any abrasive wear to the ball will cause leakage when the valve is closed. Ball valves are considered high recovery valves, having a low-pressure drop and relatively high flow capacity. At Oliver Valves, valves are our specialty; here are the advantages of ball valves.
Oliver's ball valve is known for its quality, durability, simplicity, and excellent sealing properties and they provide excellent shutoff even after years of service. This makes the Oliver ball valve an excellent choice as a shut-off valve; due to its design, they also provide better resistance to contaminated materials than other valves.
High-pressure ball valves are designed to operate in a fully open and fully closed position. High-Pressure Ball Valves are suitable for installing piping systems with connections at the same pressure load and corresponding connections or between flanges of the same pressure load and flange connection.
A high-pressure Ball Valve provides an unrestricted flow of fluids and a way to shut off that flow using the attached handle or actuator. High-pressure ball valves are used in systems that demand reliable shut-off power. Some fields of application are:
Ball valves take a leading role in the valve industry as the scope of application is enormous. Low-pressure ball valves are mainly used for critical applications with demanding requirements; they are highly used for the smooth working of water, oil and gas systems.
A low-pressure ball valve can be divided into a full bore ball valve and a reduced bore ball valve based on the flow of passage formed.
Low-Pressure ball valves are widely leveraged for water, general oil and gas applications.
If you would like more information about the ball valves we supply, please contact Oliver Valves today.
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