Ball valves are mechanical devices that are employed in piping systems to either restrict or permit the movement of a fluid (liquid or gas). They are referred to as quarter-turn valves because all it takes to switch the valve’s position from fully open to fully closed, or vice versa, is a 90° rotation of the handle. The many 360° revolutions required for other valve types, such as gate or globe valves, contrast with the rapid quarter-turn movement required for ball valves.
Ball valves have an internal mechanism that is a spherical ball with a hole drilled through it that changes the flow through the device. This hole serves as the valve’s flow control. Ball valves are frequently chosen as a solution for shut-off applications because of their reputation for overall toughness, extended service life, and reliable sealing. Compared to other valve types, they are particularly capable of tolerating contaminated media. They are typically not utilized for accurate flow regulation because alternative valve types, including needle valves, enable finer flow rate measurement. There are some unique designs that allow for some flow management.
This article will provide details on ball valves, including their construction, many varieties, uses, and important requirements. Consult our linked guide Understanding Valves for more information on valve types.
Construction of a Ball Valve
The following are the main parts that go into making a ball valve:
- Valve body
- Ball flow control
- Valve seats
- Valve stem
- Packing
- Bonnet
- Actuator
Valve Body
The main assembly that serves as the pressure vessel and into which the other ball valve parts are assembled is called the valve body. Several different types of materials, including steel, brass, bronze, cast iron, stainless steel, aluminum, PVC, and CPVC, are used to make valve bodies. The valve body can be created as a single component, two sections, or more that are bolted together. Single-piece designs cannot be fixed and must have the valve replaced in the case of a failure, whereas multi-piece designs can be dismantled for repair.
Ball Flow Control
The ball, which is the ball valve’s flow control mechanism, is a sphere through which a hole or tunnel has been drilled to permit fluid to pass through it when the ball is positioned with the hole parallel to the direction of fluid flow. The valve can be opened or closed by rotating the ball 90 degrees, which is made possible by its attachment to a stem. The ball may have a floating design, in which it would float in the medium while being held in place by the valve seats. Under the normal pressure of the fluid flow in the valve, the ball can float inside the chamber of the valve body. By pressing on the downstream valve seat as a result of the ball’s minor movement, a positive seal is produced. The load on the valve seats is lessened by another design, known as a trunnion ball or trunnion mount, which supports the ball on the top and bottom. Trunnion ball valves are employed in large-diameter valve applications or when high pressures are present during operation.
One of several varieties can be used to describe the tunnel or hole in a ball valve:
- Full bore
- Reduced bore
- V-port or slotted port
The diameter of the bore in full-bore designs is the same as the pipe’s diameter. Through the use of pigging, this design makes cleanup simpler and decreases friction losses. These types are more expensive than reduced-bore designs because they do have larger housings.
The majority of ball valves have reduced bore designs and typically have one-piece bodies. There are some friction losses because the diameter of the bore in the ball is smaller than the pipe ID, but they are typically less severe than with other types of valves.
In V-port ball valves, the ball’s typical bore has a cross-section in the shape of a “V,” in place of the traditional circular cross-section. These designs come in a range of internal angles, from 15° to 90°, and some allow for the retrofitting of ball valves from round bore to V-port designs. When a small pressure drop or tight shutdown is required in high-flow rate applications, the V-port ball is employed in place of a circular bore ball. In contrast to circular bore designs, which are very non-linear, they can provide a better level of flow control or rangeability and can approach a linear flow profile as a function of actuator position.
A shutdown valve can be retrofitted to become a flow control valve, changing its purpose.
Valve Covers
The valve seats prevent leaks by sealing against the ball and enabling leak-free valve operation. The choice of an appropriate valve seat material is influenced by the operating conditions, and seat material alternatives include metals and fluoropolymers (i.e. temperature, pressure, and the nature of the fluid being passed through the ball valve, and desired operating torque, for example.) Typical choices for valve seat materials include:
- PTFE (polytetrafluoroethylene)
- Carbon-fibre-filled PTFE
- Carbon
- Metals
- Ceramic
- PEEK (Polyether ether ketone)
- Acetal (Polyoxymethylene – POM)
- UHMW (Ultra-high molecular weight polyethene)
As opposed to metal seated valves, ball valves with flexible seat materials are referred to as soft seat valves. Additionally, graphite-seated ball valves are readily available.
Stem, Packing, and Bonnet of the Valve
The valve stem is a shaft that attaches to the ball and protrudes through the valve body to connect to the valve’s actuation system. Packing material surrounds the valve stem, sealing it and preventing fluid or media from leaking through the valve body’s aperture. Additionally, O-rings are utilized to seal the valve and stop leakage. Some designs employ a system of lubricating seals. Sometimes referred to as the valve bonnet, the area of the valve body that houses the stem and packing material.
Actuator
The device that regulates the valve’s placement from open to closed is known as the valve actuator. Ball valves can be turned on or off manually with a hand lever, mechanically, or electrically. Pneumatics or hydraulics may be used in mechanical actuation. In order to reduce the actuator’s rotational speed and avoid water hammer, electrical actuation often uses a motor and decreasing gear system.
Various Ball Valve Types
The characteristics of ball valves can be categorized in a number of ways. These can be determined by the material used in their construction (usually the material of the valve body), the construction of the valve body, the configuration of the valve, or by some other factor, such as the type of fluid handled or the characteristics of the internal design elements.
The types of ball valves characterized by the valve body material include:
- Brass ball valves
- Stainless steel ball valves
- Plastic ball valves (includes PVC and other polymers such as polypropylene and PVDF)
- Bronze ball valves
- Cast iron ball valves
- Steel ball valves
Looked at from the perspective of valve body construction, the types of ball valves include:
- Split-body ball valves
- Top-entry ball valves
- End-entry ball valves
- One-piece ball valves
- Two-piece ball valves
- Three-piece ball valves
Ball valves can also be distinguished by their valve configuration. The most popular type of valve is a 2-way ball valve, which features an inline configuration with the valve body immediately in the piping system’s flow channel. To provide cutoff service, these are used. Emphor IPS is known for leading Ball valve suppliers in UAE. Additionally, 3-way and 4-way ball valves are readily accessible. Three-way designs, which come in an “L” or “T” form, can be used to mix, blend, or redirect flows as well as distribute the fluid flow to two different ports. Some potential flow configurations for a 3-way ball valve are shown in Figure 1 below.
A 4-way ball valve is identical to a 3-way ball valve in functionality and would have 4 openings on the valve body. Some designs allow the reconfiguration of valve ports to serve as inlets or block flow ports and use bolted-on ends. Other techniques for characterizing ball valves include the fluid they are made to handle or a particular design element. Examples of these are hydraulic ball valves, which can be used in high-pressure applications like hydraulic circuits.
Ball valves with linings have a non-reactive lining or coating applied to the inside surfaces of the valve body. By adding this lining, the valve is shielded from corrosive or caustic chemicals, has a better flow coefficient due to reduced friction, and is protected from potential fluid contamination.
Details & Characteristics
The following list of essential elements and characteristics serves as a brief summary. This information should be considered general knowledge and will assist in preparing for interactions with suppliers because there may be some variations in these criteria among manufacturers or suppliers.
The material used to construct the valve body or housing, such as bronze, brass, brass alloy, PVC, PVDF, or stainless steel. The number of ports determines the valve’s porting configuration, which may be 2-way, 3-way, or 4-way.
Ball Mate
Rial refers to the substance used to make the flow control ball. Plastic, chrome-plated steel, brass, and stainless steel are typical material choices. As a single-piece or multi-piece design, the body style or type reflects the design aesthetic of the housing.
Valve shape – Depicts an inline, L, T, or Y-shaped Valve
The diameter of the pipe into which the valve is being installed is known as the pipe size. Pipe sizes and common ball valve sizes match up to make sizing and installation easier. The port design and ball bore, such as full bore, reduced bore, or V-port, are reflected in the port style. The desired port connection fitting style for the valve is represented by the connection type. Solder connect, threaded, flanged, and socket weld or socket connect union were typical possibilities. The connection type’s gender indicates whether it is male or female. The thread type, such as NPT, UNF, NPTF, BSPT, etc., on the valve port, is reflected in the thread type of threaded ball valves connections. The material used to construct the valve seat, such as metal, ceramic, or a soft seat made of fluoropolymer, is referred to as seat material. The components of the valve seal are known as the seal material.
The flow rate, also known as the flow coefficient, is a measurement of how well a valve can move fluid per unit of time. The number of US gallons of water at 60°F that may travel through the valve in one minute with a 1 psi pressure drop is known as the flow coefficient, or Cv.
The safe operating pressure range for the valve is determined by the maximum rated pressure or pressure range. This number could potentially represent the operational temperature. The type of liquid or gas to which the valve will be exposed, such as water, natural gas, fuel oil, air, hydraulic oil, food, solvents, etc. The appropriate materials for the valve body, seals, seats, balls, and other components will be determined by the type of media and its characteristics. The term “actuation type” refers to the method used to open or close a ball valve, such as manual (handle or lever), hydraulic, pneumatic, or electrical.
Operating torque, measured in N-m or lbs-F, is the force required to turn the valve between the open and closed states.
Applications, Benefits, and Restrictions of Ball Valves
Ball valves are utilized throughout a wide range of industries. Chemical, oil and gas, pharmaceutical, food processing, HVAC, sanitary applications, and other areas including cryogenics and corrosive media are a few of these. Ball valves are frequently employed in home settings as well as in many manufacturing operations. As long as the material choice for the valve components was made with the type of media in mind, they can efficiently operate with a wide range of media, including liquids, gases, chemicals, potable water, fuels, and food and beverages.
Ball valves, unlike certain other valve shapes like globe or gate valves, are very simple to operate, open and close quickly, and come in multi-port configurations. Additionally, they can be less expensive than other valve designs and are smaller and lighter. They have a long service life and are dependable equipment. They may also operate with less torque than other valves.
A further benefit is that the ball valve may operate without having to worry about side loads, a problem that frequently affects globe or butterfly valves. Some designs also make it possible to retrofit or repair the valve quickly if seats or seals start to fail, all without removing the valve body from its mounting.
One drawback of ball valves is the potential for suspended particles to become trapped in the valves’ body cavities when used in slurry applications. This can cause the valves to wear out too quickly, leak, or fail altogether, necessitating replacement. They are mostly best suited for shut-off service applications, as was indicated at the beginning of this page, while other designs, like the V-ported ball valve, have the capacity to regulate flow.
Summary
This article provided a summary of ball valves, including their construction, the different types, key specifications, and advantages and limitations. For information on other topics, consult our additional guides or visit our website where you can locate potential sources of supply for many different product and service categories, including Valve and Ball valve suppliers in UAE. Reach out to us now!
