As the most common valve type in the piping industry, floating ball valves play an important role in regulating flow through pipelines and other piping systems in the gas, oil, water and other industries. They create a bi-directional seal, and can even be customized for high pressure operations, though normally they are only used in pipelines with low to medium pressure. Available in different configurations and sizes, they feature a ball-shaped disk that’s hollow and perforated, so that liquids can pass through it when open. If you’ve found yourself wondering “What is a floating ball valve?” simply keep reading – the team at Arthur Harris has broken it down for you below.
What is a Floating Ball Valve & How Does it Work?
Though floating ball valves have numerous applications, their purpose is essentially just to control how liquids flow through pipelines, though these aren’t the only type of ball valve used for this purpose. The other major type – a trunnion ball valve – is also used for such purposes, and a bit later we’ll compare it to the floating variety.
A floating ball valve gets its name from the hollow, ball-like sphere that “floats” freely inside the valve’s body, which is compressed between two flexible seats while suspended in liquid. What a floating ball valve normally does during operation is float slightly downstream, which causes the seating mechanism to compress under the ball. Should the seating disintegrate, the ball floats to the metal stem to seal it. This provides a failsafe within the design.
The system also involves a stem in the valve’s body that connects it to a slot at the top of the ball and allows the ball to rotate 90 degrees. This stem allows the ball to move laterally when upstream pressure acts on it, while the other downstream seat improves the tightness of the valve’s seal. This allows the valve to close when liquid flows in either direction.
The ball itself has a hole through which liquids pass freely when it’s correctly aligned with both ends of the valve. This hole, when perpendicular, seals the valve. When this hole is in any other position, liquid will continue to flow through it. The floating ball valve can stop, distribute and alter the direction liquids flow within a pipeline, with its main features being the sealing design of the seats, which automatically relieve pressure, reliably sealing when flows reverse and acting as a locking device.
Pressure acts on the closed valve on the backside of the upstream seat as well as the ball, which forces the ball in the direction of the downstream seat. This force both deforms and limits the valve seats. This temporary deformation is engineered into the seats’ design, using stored energy to temporarily change its shape in order to keep the seal when temperatures or pressure changes.
What is a Floating Ball Valve Used For?
Floating ball valves provide an air-tight seal when completely closed, so offer a variety of industries a key method for regulating flow of liquids such as oil, natural gas, steam and water. They have from one to three pieces welded, forged or otherwise joined together, with differing uses for each type:
- One-piece floating ball valves have a single forged or cast steel body, which houses all the moving valve parts. These single-piece floating ball valves are the most compact and the least expensive, so are used in smaller applications. As they can’t be opened for cleaning or repair, they’re used mainly in pipes carrying gasses, which normally require very little maintenance.
- Two-piece floating ball valves have two housing pieces cast together or forged, with one piece always larger than the other. The larger piece houses the moving parts, and unlike the single variety it can be opened to repair, maintain or clean it, though it must be disconnected from the pipeline in order to do so.
- Three-piece floating ball valves have three pieces of housing, and are the most expensive subtype. Though they tend to be larger, there are smaller sized three-piece floating ball valves designed for use in compact situations. These sections are forged to each other, with one half of the body being larger and housing all the moving valve parts. It’s the easiest to maintain, repair or clean, as it need not be removed from the pipeline.
All three types of floating ball valves allow bidirectional flow cut-off. With a very compact design compared to other isolating valves, it’s ideal to use when space is an issue. There are a wide range of industries and environments in which floating ball valves are used, including the gas processing, petrochemical, chemical and natural gas industries as well as offshore and onshore oil and gas wells, transmission lines, storage facilities and in a multitude of other industries where gas or liquids are transported via piping systems.
Advantages & Disadvantages
Floating ball valves are most often used in applications that require medium to low-pressure valves, and are well-suited for both liquids and gases. Lightweight and economical, the seating cannot operate as safely and efficiently with heavier balls.
Floating ball valves advantages include:
- Compact design
- Little flow resistance
- Reliable sealing functions
- Uncomplicated construction
Floating ball valves have disadvantages as well, which include:
- Complete reliance on downstream seating when carrying a medium load.
- Difficult to operate when upstream pressure is high.
- Seating directly absorbs ball’s gravity, so is unable to reliably withstand higher pressures or larger balls.
Floating ball valves are just one type of valve commonly used for regulating flow through pipelines, which also use trunnion mounted ball valves. Typically, the trunnion valves are used for higher pressure applications, and in larger pipelines. Trunnions can more easily handle slurry mediums as well as the liquid and gaseous composition handled by floating ball valves.
Contact the Experts at Arthur Harris
Arthur Harris & Company manufactures floats for just about any application. The company’s wealth of knowledge and experience makes it an ideal partner for any industry that requires stainless steel floats, offering them in various shapes, sizes, metals, connections and gauges. The technical staff at Arthur Harris can assist customers in choosing the right floats to meet your needs.