A Guide to Ball Valves
This guide has been designed to provide a comprehensive overview of the Stainless Steel Ball Valves available, the associated spare parts as well as their uses. Its Purpose is to provide the necessary information required in order to select the correct ball valve for a particular application.
What is a Ball Valve?
A Ball valve is a type of shut-off valve that is used to control flow where a simple ‘on’ or ‘off’ flow is required. They are easy to operate and can "shut off" or "open" flow with a simple 90 degree turn of the handle. The name is derived from the spherical internal ball that has a hole bored-through it, which rotates to open and close the flow. They are versatile able to transfer liquids and gasses in a wide pressure and temperature range. They are reliable, capable of repeating the same function of sealing well after many cycles, even after extended periods of disuse. They are durable and have a long and predictable service life.
Types of Ball Valves
How Does a Ball Valve Work?
They Utilize a hollow ball that rotates allowing a flow through it when aligned and stops the flow when it is in a closed position. A quick 90 Degree turn of the handle is all that is needed to fully open or close the valve flow. When the handle is parallel and in-line with the pipe, then the valve is open. When the handle is perpendicular and at right angles to the pipe, then the valve is closed. It is this 90° turn either clock wise or anti-clockwise to open or shut the flow of the valve ,that led them to also be known as quarter-turn valves. The valve has an internal rotary ball with a hollow bore running through the center. This Inner ball is connected to the handle via a stem. So by turning the handle the ball rotates and when the hollow bore is aligned with the pipe and the in same direction as the flow, then the flow is open, and when the bore is perpendicular to the flow, then flow is shut off.
Ball Valve Components
Although there are numerous parts making up the valve the basic components are made up of the following:
● The Valve Body
Also referred to as the valve housing or shell, it contains all the inner components of the valve. Usually composed of a rigid metal, in this case Stainless Steel, it protects all the internal components and keeps them in the correct position and aligned for proper functioning. It also facilitated access for the external handle to connect with and rotate the internal ball, via the stem. The valve body comes in three assembly options: one-piece, two piece and three-piece designs.
● The Rotary Ball
This is the part that gave the valve its name. It is a ball that has "flow path" known as a bore, through the center that allows the medium to flow through it. The ball is rotated by the stem, which either opens the flow when the bore is in-line with the pipe or closes the flow when the bore is perpendicular to the flow. There are two types of bore design: Full port and Reduced port.
● The Stem
Also referred to as the shaft, it connects the external handle that rotates the inner ball. The Stem has washers and packing rings to ensure a tight seal and to prevent any leaks. The stem is rotated as the handle is turned, which in turn rotates the ball, opening and closing the flow.
● The Seat
The Seat sits between the ball and the valve body and ensures a water tight seal. There are two seats that sit on either side of the ball and are usually composed of Teflon (PTFE).
● The Handle
The handle is also often called the lever. it a standard ball valve it is the manual way used to turn the ball valve to the open or closed position.
Benefits of using a Ball Valve
- ● Ease of Use: They open and close quickly using minumal force with a simple 90 degree (quarter-turn) of the handle and require no tools for operation.
- ● Quick Installation: They are quick and easy to install using simple threaded ends as a method of connecting in-line to an application.
- ● Versatile: They are good for high pressure, high temperature and high flow making them suitable for a wide range of industrial applications.
- ● Durable: Their simple robust design provides resistance to general wear and tear ensuring a long service life of reliable use.
- ● Reliable: They are designed for repeatable use of leak free service, that is to repeat their function of opening and closing flow in the same way for the life of the valve.
- ● Cost Effective: They are the most cost effective of all the valves.
- ● Low Maintenance: Since they are low maintanance and require little to no service, this results to additional long term cost savings.
- ● No Lubrication required: The Teflon seats holding the ball function well in wet and dry situations.
- ● Low Pressure Drop: They have a high flow capacity and low pressure drop due to the size of the bore in the ball. when fully open there is little to no resistance to the flow of fluid.
- ● Compact: Smaller than other options like gate and butterfly valves.
- Since they are so durable and reliable this makes them suitable for almost all environments and very well suited to most applications where repeatable "on/off" flow is required. Also in situations where valves are left open or closed for years and then resume normal function without any impact on performance.
limitations of a Ball Valve
- ● Throttling: Ball valves can be used for throttling however they are not suitable for long term throttling, best if used in either the fully open or the fully closed positions. When used in the throttling position either half open or half closed, the seats are exposed to the flow and can be subjected to erosion if the fluid velocity and pressure is high enough.
- ● Temperature rating: is determined by the Teflon seats, for higher temperatures ceramic or metal seats are used.
- ● Particle build up: Slurries and suspension mixtures have suspended particles that could build up around the ball which could necessitate frequent maintenance.
Selecting the correct Ball Valve
- ● Bore Size: Determine the internal diameter needed for your required flowrate: Reduced Port or Full port. Full port is designed for maximum flow rate and is also good for mixtures.
- ● Type: 1-Piece, 2-Piece, 3-Piece and 3-way ball valves. 1-Piece are the most cost effective. 2-Piece are used when a full flow is required. 3-Piece is used when regular cleaning is needed. 3-way is used for mixing or when multiple inputs are needed.
- ● Materials of Construction: Chemical compatibility varies depending on the material of the valve body. Stainless Steel 316 is the most versatile and can be used on corrosive madia. Stainless Steel 304 is a better priced alternative good for most applications. Brass is traditionally used on water, oil and air applications, however more and more brass is being replaced with the ever better price of the 304 stainless steel. PVC valves are lighter and used with acids & bases as well as with organic solvents.
- ● Pressure: Operating pressure ratings vary for ball valves the standard we stock being 1000 psi which covers most application. we also stock 2000 psi and 3000 psi ball valves for more unique applications.
- ● Temperature: The temprature rating can vary dependign on size. Stainless steel and the Teflon seats generally withstand high tempratures, to be safe consider -13⁰F to 302⁰F.
- ● End Connection: Most ball valves have Female NPT threaded ends. They can also be manufactured with Male NPT threads and Female NPT thread. Other common alternate methods of connections are butt weld ends and flange ends.
- ● Port Count: The most common is the two-way ball valve which has two ports, an inlet and a outlet. This bi-directional valve can carry media in both directions. we also stock 3-way ball valves with have three ports.
- ● Actuation method: The most common is manual operation by turning the handle. Electronic or pneamatic actuators can be fitted to the valve for remote operation.
There are two main types of bore profiles: Full Port and Reduced Port. The bore refers to the size of the hole that is drilled or bored into the ball. This bore or hole through the ball is also referred to as a port. A full bore is also called a full port and a reduced bore is also called a reduced port.
● Full Port
A full bore has a internal diameter that is the same as the pipe it is connected to. This allows the flow rate to remain constant through the length of the line, this means a full port valve has a very low flow resistance. Since the flow resistance is so low, there is minimal friction loss during the flow of the fluid, and as a result the pressure drop is negligible. This low Pressure drop in the application makes pumping the process fluid much easier.
Since the internal diameter of the port is the same as the pipe size, a full port valve is made with a larger ball which necessitates a larger valve body. This results in a slightly larger and more expensive valve than that of a reduced port valve.
Full port vales are suitable for transporting fluids with mixed solids, where any restriction in flow could result in particle build up that could in the long term cause separation of the mixtures flowing through it.
Full port valves are also easier to clean as opposed to the reduced port. In a process called "pigging" pipes are inspected and cleaned. This process involves using projectile devices called "pigs", which are used to flow in the pipes and remove particle build up. This process can only be performed on full bore valves that have the same internal diameter as the process piping they are connected to, and is not suitable for reduced bore valves or butterfly valves.
● Reduced Port
A reduced bore has a internal diameter that is one pipe size smaller than the pipe size it is connected to. So a 1" Reduced port ball valve with have a 3/4" Internal Diameter. Since the piping internal diameter becomes smaller at the valve, this reduces the flow area and causes flow resistance, which in turn results in a pressure drop. Since the amount of flow stays the same, the flow rate increases as the flow area decreases due to the narrower pipe diameter of the reduced bore.
Since the ball is smaller in a reduced port valve it requires a smaller valve body. This results in a smaller and less expensive valve. They are ideal for applications where flow rate is not a concern and the build up of particles is not likley to occur.
The most common types of manual ball valves are the 1-Piece, 2-Piece and 3-Piece. Another relatively common type is the 3-way ball valve, these 4 types account for the vast majority of the most often used valves.
● One Piece
A One-Piece has valve body cast out of a single piece of material. This means that there no joints in the body which eliminates the risk of leaks. The one-piece has a smaller body than the other valves making it the most cost effective. This also results in a smaller ball which means one-piece valves always have a reduced port. This means the internal diameter of the pipe decreases by one size at the point where the valve is installed. they are generally used where cleaning is not a concern and where the possibility of particle build up is low.
● Two Piece
A Two-Piece has a valve body cast out of two pieces that thread together. The two-piece has a larger body which allows for a larger ball which means a full port is possible. This means the internal diameter of pipe the remains constant throughout the pipe, once the valve is installed. They are the most commonly used among all the ball valve types and are good for mixtures and applications where an optimal flow rate is preferred. The Valve body can be dismantled for cleaning and to service the seals, however the valve will have to be removed from the pipe, unlike the three piece.
● Three Piece
A Three-Piece has valve body cast out of three pieces that are held together by bolt connections fitted to each of the two ends. The three-piece also has a larger body which allows for a larger ball with a full port. They are ideal for applications where regular maintenance and cleaning is required. By loosening the bolt connections the valve separates into three parts and the internal ball and seats can be accessed without removing the two ends connected to the pipe. This makes them ideal for food & beverage applications and in pharmaceutical industries where sanitation and regular cleaning is required.
● Three Way
These mulit-port valves are used in mixing or splitting flow (T-Port) and also for diverting (L-Port) multiple streams of fluid. This is achieved by means of a L-shaped or T-shaped bore in the ball. On top of this they also open and close the flow to multiple fluid streams. There are two types of 3-way ball valves L-Port and T-Port:
- ● Used as diverter valves directing flow from a single inlet to one of two outlets.
- ● Also used as selector valves selecting one of two inlets to flow to a single outlet.
- ● Used as mixing valves combining flow from two inlets into a single outlet.
- ● Also used for splitting flow from a single inlet to two outlets simultaneously.
Materials of Construction
For general industrial purposed ball valves are most commonly manufactured out of Brass, Stainless Steel and Polypropylene.
Brass is a metal alloy composed of copper and zinc that ranges in color from yellow to red, depending on the concentration of zinc. Traditionally brass was the most common material used for manufacturing ball valves. This trend appears to be changing due to the increasingly better price of stainless steel. Brass is resistant to most Acids and Alkalis with the exception of solutions with high chlorine levels which can cause dezincification. They are particularly resistant to salt water. Brass valves are often used in oil and gas processing and are also used for water applications.
● Stainless Steel
Stainless steel is a metal alloy composed characteristically of higher levels of iron, chromium and sometimes, nickel. It is the Chromium content in particular that allows this steel alloy to acquire its exceptional corrosion resistance. Strong, corrosion-resistant and able to handle extreme temperatures, they are the most diverse of the commonly used valves. They are well suited to handle chlorinated water which is why they are often used in applications connected to swimming pools. they are also suited to extreme industrial conditions like petroleum refineries and desalination plants since they offer good corrosive resistance to chemicals even under high pressure and high temperature conditions. Widely used in wineries and breweries, stainless steel is well suited to handle hot wort, made during the mashing process to produce beer.
- Stainless steel is commonly manufacturer in two grades: 304 and 316.
- Stainless Steel 304: Chromium 18% and Nickel 8%.
- Stainless Steel 316: Chromium 18%, Nickel 8% and Molybdenum 2%.
Iron is an abundant low cost metal that is prone to rust. They can withstand a large range of temperature and pressure. Iron is generally made into Cast Iron and Ductile Iron ball valves. Ductile iron is more robust and offers better resistance to fatigue and to impact. Iron valves are most often used in water, oil, steam, and gas pipeline applications.
Polypropylene is a thermoplastic polymer made by combining propylene monomers. It has good resistance to many acids and bases but when it comes to organic solvents it offers only selective compatibility. As temperature increases its pressure rating and chemical resistance decreases. Widely used in the manufacturing industry for fertilizers, chemicals, paper and suger etc.
PVC is an acronym for polyvinyl chloride. PVC is resistant to most acids, bases, salt solutions, and organic solvents. It is not suitable for chlorinated and aromatic hydrocarbons, and it is also not suitable for temperatures above 140 °F. PVC ball valves have a lower pressure rating since they are not as strong as metal ball valves. They are widely used in water supply & drainage, irrigation and also for corrosive media.
Material Comparison Table
Inert, Abrasive & Corrosion Resistant
Higher Price (Constantly Decreasing Relative to Brass)
Prone to Dezincification
Cost-Effective, Corrosion Resistant
Shorter Service Time, Limited Pressure & Temperature
There are numersous parts of contruction that make aup a ball valve. however are far as replace ments part go it is usually only the seats that may require servicing over time and occasionally the handles. For a full like of parts that make up a 2-Piece Ball valve see the diagram below.
● Ball Valve Handles
The handle is used to turn the valve from the open to the closed position. It does this by turning 90 degrees. It is connected to the stem which in turn connects to the ball. The valve is in the open position when the handle is in-line or parallel to the pipe and it is in the closed position when the handle is at right angles to the pipe. In this way the handle position let the user know if the valve is open or if it is closed. Handles can be replaced and handle covers can be specially branded.
● Seats and Seals
Generally Valve Seats are made out of Teflon (PTFE). PTFE Is an abbreviation of Polytetrafluorethylene. PTFE is chemical and corrosion resistant and is very good at handling temperature extremes. On top of that the coefficient of friction is small which means the handles is relatively easy to turn.
Where are Ball Valves Used?
They can be used with a full range of media, which include liquids, gases, water, chemicals, fuels and food & beverage, as long as the material selection for the valve is compatible with the media being transferred. Due to their relative low cost, ease of use and versatility ball valves are used in almost any industry that uses liquid or gas. These include fuel, oil & gas, chemical, pharmaceutical, food & beverage processing, HVAC and sanitary applications. They are also widely used in many manufacturing processes and in residential applications. Their versatility also enables them to be used corrosive applications and cryogenics.
- ● Original Equipment manufacturers (OEM’s): Many manufactures routinely use ball valve in their production processes.
- ● Breweries: Often installed on Kettles to control flow during transfers. During the process of “mashing” the valves facilitate the flow of hot “wort” which is corrosive.
- ● Tanks: Ball valves are often place on tanks to control flow and prevent unwanted drainage.
- ● Piping systems: Corrosion resistant Poly Camlocks are well suited to agricultural applications.
- ● Agriculture: Although Poly ball valves are predominantly used stainless steel valves are well suited to deal with chemicals, fertilizers, humidity and extreme temperature fluctuations.
- ● Sanitation & Waste Water: Stainless Steel valves are widely used in water treatment and purification plants.
- ● Oil & Gas: Upstream they are used to control oil flow, midstream they protect equipment by regulation oil and gas flow and downstream they are used in the process of refining of crude oil.
- ● Oil Refining: Crude oil is corrosive as it may contain water, sulphur, carbon dioxide and micro-organisms. This make makes corrosion resistant stainless steel ball valves the perfect choice in an oil refinery.
- ● Marine Applications: Sea water is corrosive to most materials especially metals due to the sodium and chloride content. Stainless steel is ideal being able to handle extreme temperatures as well as being high pressure and corrosion resistant.
- ● Residential and Commercial Plumbing: Brass ball valves have traditionally been used however Stainless steel ball valves are more suitable now. They are better priced and cleaner, since Stainless steel is lead free.
- ● Water Well: Typically brass valves were used and it appears the lead free stainless will become more and more popular for water and water well applications.
- ● HVAC: widely used in HVAC and refrigeration systems they are suitable to be used in sub-critical systems.
- ● Fuel and Oil: The presence of numerous connecting hoses which are so prevalent in the petrochemical industry means that there is flow that need to be controlled. Historically brass valves were mostly used and this is slowly moving to stainless valves as the relative price of stainless steel continues to improve.