All You Need to Know About Ball Valves
What are Ball Valves?
Ball valves are quarter-turn valves that use a hollow, perforated, and pivoting ball to control the flow of materials from one opening to the next. The valve can be open, closed, or partially open to allow gasses, liquids, and slurry materials pass through it. Ball valves are used in applications where tight shut-off is required.
Ball valves are extremely versatile as they can handle pressures up to 1000 bars and temperatures up to 400 degrees. Their sizes range from 0.5 cm to 121 cm and they are easy to operate and repair. Ball valves are designed to allow only a 90-degree rotation for opening and closing the valve. This means the valve locks fully when the handle is turned. Ball valves are popular in industrial use because of the air-tight seal they provide when fully closed.
What are the Different Components of a Ball Valve?
Ball valves can be made of metal, plastic, or metal fused with ceramic. The ball in the valve is usually chrome plated for durability. Just like other industrial valves, ball valves also feature certain moving parts. Here are the components of a ball valve:
Body or Shell
The body of a ball valve houses all other components of the valve. It also serves as the first pressure boundary of the valve. This is because it provides the first line of resistance against the flow of materials through pipes connected to the valve. The body of a ball valve provides the main framework of the valve. It protects the other components and also holds them together.
The bonnet of a ball valve covers the opening of the valve’s body. It is usually bolted or screwed to the body making sure it stays intact. Bonnets form the second pressure boundary of the valve as they reinforce the strength of the body in countering the pressure of materials flowing through the pipes connected to the valve. The bonnet of a ball valve is usually made of the same material as the body of the valve to make it stronger and durable.
The trim of a ball valve features all the moving parts of the valve. This includes the ball (disk), seat, stem, and sleeves. The ball in the valve acts as its disk. This hollow sphere is placed in the center of the valve and it turns to allow materials to pass through. The ball acts as the third pressure boundary of the valve as it comes in direct contact with the materials flowing inside the pipes connected to the valve. The stem of the ball valve connects the ball to the actuator. As the actuator is turned, the stem moves as well, in turn, rotating the ball. The stem connects the ball to the actuator through welded joints. The seat of the ball valve is where the ball is placed. The seat is also known as ‘seal ring’ as it nestles the ball inside and provides a snug fit when the valve is closed.
The actuator of the ball valve is what we use to open and close the valve. Handwheels, levers, motors, solenoids, pneumatic operators, and hydraulic arms are all examples of ball valve actuators. Most ball valve manufacturers produce ball valves where the actuator is mounted over the bonnet through a yoke.
As the name suggests, packing prevents any leaks through the stem. Ball valve packing can be found in the space between the stem and the bonnet. It is usually made of fibrous materials like flax or Teflon. Packing provides protection to the internal parts of the valve and it forms a seal over them to prevent any leakages.
How Does a Ball Valve Work?
Ball valves are shut-off valves that use a ball to start or stop the flow of materials through the valve. The ball in the valve performs the same function as the disc in other valves. The ball is hollow and features a hole that is also known as the bore. When the actuator is moved, the ball rotates to a point where part or the entire bore is in line with the valve body inlet and outlet. This allows the materials to flow through the valve.
To close the valve, the actuator is moved again. The ball rotates to a point where the bore is perpendicular to the flow path. This causes the flow to stop. Most ball valves require a 90-degree turn of the actuator to fully open or close. The valve can be partially opened but that causes damage to the ball valve. This is the reason why ball valves do not belong to valves recommended for throttle applications. They are most suitable for applications where tight shutoff is necessary for example to control the flow of gas.
Ball valves can be unidirectional, bidirectional, or multidirectional depending on the number of valve seats and ports. For example, a two-way ball valve with a single seat will be unidirectional with flow direction indicated on the valve. The same valve with two seats will be bidirectional. In this valve, one seat will be on the upstream side while the other will be on the downstream side of the ball. Three-way, four-way, and five-way multiport ball valves can be unidirectional if the flow is entering through a designated port. Ball valves with multiple ports allow flow in more than one direction eliminating the need for several valves.
What Types of Ball Valves are Used in Piping?
Ball valves don’t have a complicated mechanism. They are easy to install and simple to use. Their simple design makes them versatile, they can be used in many different industrial applications. There are many types of ball valves depending upon their body construction and function.
Types Based on Body Configuration
Ball valve manufacturers categorize these valves on the basis of their body configuration. There are four types of ball valves based on their construction.
Top Entry Ball Valve
As the name suggests, top entry ball valves allow access to the internal parts of the valve by removing the bonnet cover on the top. These valves can be easily assembled and disassembled. Easy access allows repair and maintenance without having to disengage the ball valve from the pipeline.
End Entry Ball Valve
These ball valves have a single-piece body. The connections on the valve are flanged or screwed. The ball is inserted from one end and is kept in place by a screwed insert. End entry ball valves are usually smaller in size and used for applications requiring less pressure.
Split Body Ball Valve
In split body ball valves, the body of the valve is divided into two or three pieces that are bolted together like flanges. One part of the body is always larger than the rest and that is what holds the ball. The stuffing box is constructed around the larger body part. Split body ball valves are usually larger in size, though you can find smaller ones as well. They are easy to inspect and maintain.
Welded Body Ball Valve
In welded body ball valves the bonnet is welded to the body of the valve. This makes the valve safe from any kind of leakages. The valve’s internal parts cannot be accessed or maintained. Welded body valves are suitable for underground applications, submarine pipelines, and for regulating the flow of hazardous materials.
Types Based on Ball Movement
Ball movement indicates how a ball valve functions. There are three types of ball valves based on ball movement.
Floating Ball Valve
In this type of valve, the ball is attached only to the stem of the valve. It is kept in place by the compression of two elastomeric seats against the ball. But the ball has some space to freely float between the seats. When upstream pressure is generated in the valve, the ball gets pressed against the downstream seat producing a tight seal. This type of valve can thus provide bi-directional shut-off.
Trunnion Ball Valve
Floating ball valves are difficult to operate in high pressure. That problem is remedied in trunnion mounted ball valves. In this type of ball valve, the ball is supported by a shaft or trunnion on its vertical rotation axis. The trunnion absorbs the pressure from the flow so the contact between the ball and seats is not overly stressed. This, in turn, reduces the operating torque. Trunnion ball valves are suitable for high pressure, large scale applications.
Rising Stem Ball Valve
Seal rubbing is one of the primary causes of valve failure. Rising stem ball valve eliminates that problem by incorporating tilt-and-turn operations. In this ball valve, a stem is inserted in the seal that prevents any direct contact between the seal and the seats. When the valve is closed, the stem wedges against the set, ensuring a tight shut-off. When the valve is open the stem tilts away from the seat so the flow can easily pass through.
Types Based on Bores
Bore is the internal diameter of the balls used in ball valves. There are three basic types of ball valves based on bores.
Full-Port Ball Valve
The full-port ball valve is named so because the diameter of the bore in this valve matches the diameter of the connected pipeline. This means there is no restriction to flow through the valve. Full-bore or full flow ball valves are ideal for situations where pigging may be required. They are used widely in chemical, petrochemical, and refining industries.
Reduced-Port Ball Valve
As the name suggests, a reduced port valve has an internal bore diameter that is one or two nominal sizes lower than the internal diameter of the connected pipeline. The flow path is restricted which results in higher energy losses. A reduced port valve is used mostly in the oil and gas industry.
V-Port Ball Valve
V-port ball valve features either a ‘v’ shaped ball or a similarly shaped seat. This ball valve is used in applications where the flow velocity needs to be maintained at a certain level. This is why v ball valve is also called a control valve.
Types Based on Number of Pieces
Ball valves can be housed in one, two, or three-piece structures.
One-Piece Ball Valve
This is the cheapest ball valve because it features a single piece of housing that is welded or forged to the body of the valve. One-piece ball valves cannot be opened so cleaning, maintenance, or replacement of parts is impossible. This ball valve is suitable for small scale industrial applications and materials like gases that do not require valve maintenance.
Two-Piece Ball Valve
This ball valve is made of two pieces of housing that are threaded together. Two-piece valves can be disassembled for cleaning and maintenance but that requires the valve to be disengaged from the pipeline.
Three-Piece Ball Valve
Three-piece ball valve features three different pieces of housing that are bolted together. The valve can be easily cleaned and maintained. The internal parts can also be replaced without disengaging the valve from the pipeline. Three-piece ball valves are more expensive than the other two types of valves in this category.
What are the Applications of Ball Valves?
Ball valves provide reliable leak protection which makes them perfect for a number of industrial applications. They have a low-pressure drop and can open and close quickly which makes them great for liquid and gas applications. Ball valves are extremely versatile so they can be used for subsea, underground, and cryogenic services.
Ball valves can be used for air, gas, and liquid applications that require bubble-tight service. They can also be used in low-point drains and high-point vents for liquid, gas, and other fluid applications. Cooling water and feed water systems can be regulated using ball valves and they can also be used for steam services.
Ball valves can be used at turbine skids, gas feed lines, compressor skids, crude oil plants, generator skids, polymer plants, separator skids, LNG plants, field gas plants, industrial gas processing plants, tank farms, oil refinery feedstock lines, hydrocarbon processing, and automated process applications. Stainless steel ball valves can be used in petroleum refining, desalination, and brewing.
What are the Pros and Cons of Using Industrial Ball Valves?
Ball valves can be used in many different industrial applications. However, they do have some limitations. Here are the pros and cons of using industrial ball valves.
- Ball valves provide bubble-tight service
- They can be opened and closed quickly
- They are smaller in size and lighter than gate valves
- Ball valves can have multiple ports which reduce the need for more valves
- They have a lot of variety in terms of construction and design
- They can be used to manage the flow of clean and slurry materials
- They provide reliable service in high-pressure and high-temperature applications
- It is easier to actuate the valve as compared to a gate or globe valve
- Ball valves can only be used for full shut-off operations. They are not suitable for sustained throttling applications
- Slurry or corrosive materials can damage the valve. Particles can settle in the body cavities of the valve causing wear, leakage, and valve failure
- Rapid opening and closing can surge pressure which could damage downstream equipment
How to Choose the Right Ball Valve for Your Needs?
There are many ball valve suppliers and manufacturers in the market who have a huge variety of these valves on display. But not all ball valves are the same. Here are some steps you should take to choose the right ball valve for your needs.
Step 1: Choose the Right Ball Valve Weight and Size
Ball valves are available in a number of sizes. You need to choose the one that is the right size for your pipeline and application. For example, you may need a full-bore hydraulic ball valve to regulate the flow of water in your hydro-power plant or a reduced-bore pneumatic ball valve to ensure proper flow of gas in your factory. In either case, the size of the bore and the ball valve will depend on the application and how you want to regulate the flow of material through the valve.
Step 2: Choose the Right Pressure Rating
Pressure rating is important because it tells you how much pressure the valve can handle. You may need a high-pressure ball valve if you want to regulate fluids or a low-pressure ball valve if you need to manage the flow of slurry materials. At SIO, we use the ASME rating to indicate the pressure rating of our ball valves. The pressure rating is represented in WOG (Water Oil Gas) so you can choose the right ball valve.
Step 3: Choose the Optimal Temperature Rating
Temperature rating tells you how much heat or cold a ball valve can handle before it hinders its operation. Stainless steel ball valves and titanium ball valves have higher temperature rating than plastic ball valves. Cryogenic ball valves can work in very low temperatures. At SIO, we mention the temperature rating of all our ball valves so you can find the one that suits your needs.
Step 4: Choose the Best Body Material
Ball valves can be made from a number of different materials. Brass ball valves, bronze ball valves, and cast iron ball valves can be used in many industries. Aluminum ball valves and forged steel ball valves are great for high-pressure applications. Our ball valves are made from high-quality materials that are sturdy and durable.
Step 5: Choose the Right Actuation
Ball valves can be actuated in a number of ways. Manual ball valves are more common in low-pressure applications. Electric ball valves and pneumatic actuated ball valves are more suited for high-pressure applications. Motorized ball valves are great for managing the flow of fluids and gasses.
Step 6: Choose Ball Valve Type Based on Media
Ball valves can be used to regulate the flow of liquids, gases, and slurries. But not all ball valves can handle all these materials. Steam ball valves are different from water ball valves. Ball valves suitable for slurry and corrosive materials will not work the same way as gas ball valves. The trim of the ball valves will change according to the media it has to regulate.
Step 7: Check the Ball Valve Standards
Ball valve design standards help you check the quality of the valve. There are certain universal standards that all good ball valves have to follow. ANSI, API, and ASME are American valve standards. They are considered to be the highest standards of quality in the market. All valves sold at SIO follow ANSI and ASME standards of quality.
Step 8: Check the Ball Valve Warranty
Just like any other machine, ball valves can also malfunction. There could be a defect in any of the many moving parts of the valve or it could be damaged. It is important to seek appropriate warranties for ball valves. SIO offers one-year warranty against all our ball valves.
How to Maintain Ball Valves?
Ball valves need regular maintenance to keep working properly. Some kinds of valves, like a single-piece ball valve, are difficult to maintain while others like 3-way hydraulic ball valve can be opened and cleaned/repaired easily. Here are some tips on how to maintain ball valves:
- Unrig the inlet and outlet pipelines of the valve before you open the ball valve for maintenance. Three-piece ball valves don’t have to be removed from the pipeline but you still need to unrig the pressure on all outlets before you start repairing or cleaning the valve
- Seal the spare parts of the ball valve when you’re cleaning or repairing the valve to make sure those parts are protected. If the ball is being used to regulate the flow of hazardous materials, sealing some parts may also help protect the maintenance workers
- Disassemble the valve by unscrewing the bolds uniformly and symmetrically. This will ensure the bolts remain undamaged and do not become loose. Screw them back in the same way
- Use appropriate cleaners for different parts of the valve. The parts made of metal should be cleaned cleaning sprays made of gas. You can use alcohol and other cleaning agents on the parts of the valve made of plastic
- Apply lubricants to the moving parts of the valve to make sure they work seamlessly. Applying lubricants to the outer parts of the valve also makes it look clean and shiny