What is a Plug Valve?
A plug valve is a type of control valve that features a conical tapering or cylindrical disc. It controls fluid movement via one or more passages that run sideways through the plug. Its 90-degree turn seals the valve and prevents fluid passage. This distinguishes it from an eccentric plug valve. This quarter-turn valve uses an offset valve to regulate wastewater flow.
Plug valves are small and simple. And mainly used for cutting, distributing, or channeling media flow. Its principal applications are in low-pressure, low-temperature environments. Although some specific types of plug valves work in high-temperature environments too.
What is a Ball Valve?
Ball valves are a type of plug valve. It features a spherical disc and a circular bored passageway. The spherical disc has a hole. It is called a port. Which corresponds to both ends of the valve. The valve has the ability to be opened and closed.
The ball valve’s principal function is to cut off, distribute, and change the flow direction of the medium. It has characteristic features make it ideal for water, solvent, acid, etc. The valve can also be used in the presence of hostile media such as methane, oxygen, hydrogen peroxide, and ethylene.
What exactly is the distinction between a Plug Valve and a Ball Valve?
Construction
Plug Valve: Valve ports are openings in the valve body that permit fluid flow in and out of the valve. Several plug valves, particularly rectangular port valves, feature a straight entire port bore. The plug valve full port allows complete fluid passage through the valve’s body.
Ball Valve: The ball valve’s full port or bore allows unrestricted medium flow. It signifies that the ball has a straight fluid flow path through the valve with no flow reduction. This is because the diameter of the hole and the size of the pipeline are the same, allowing for lesser friction loss.
Ball valve ports are available in either full or standard sizes. A full port ball valve has the same diameter as the pipe, while a standard port ball valve has a smaller diameter than the pipe. The ball valve standard port has smaller bodies overall, which corresponds to the narrowing of the valve body’s interior size.
Working Principle
Plug Valve: A plug valve’s working principle relies on a plug with a hollow passage in the valve body. The 90-degree rotation aligns the pipe with the hole, resulting in an open state. When the valve is spun to a 90-degree angle from the open position, it sits across the pipe, resulting in a closed state.
Ball Valve: A ball valve has a valve body in which a large sphere with a centrally placed hole, having the same diameter as the pipe’s internal diameter, is mounted. The valve generates the through conduit or full bore required for unrestricted fluid flow and scrapers when the ball spins at 90 degrees.
Application
When to Use Plug Valve?
In terms of performance, the plug valve outperforms the ball valve. Some of its advantages over ball valves are as follows:
- The sealing surface of the plug is much more extensive than that of ball valves and offers a better sealing effect, greater torque, and smaller diameter.
- Although several high-pressure and high-temperature plug valve designs exist, they are most commonly utilized in low-pressure-low-temperature services.
- Even in mild vacuum systems, plug valves offer a great capacity for directional flow control.
- It is also efficient in handling gas and liquid fuel.
When to Use Ball Valve?
Technological advancement makes the ball valve’s sealing effect much better today. It can only be replaced with a plug valve when the sealing requirements are stringent but with a smaller diameter. Other applications of ball valves include;
- It is better suited for applications that require faster opening and closing speed or during an emergency because of its quarter turn on/off operation.
- Ball valves are widely used in a variety of automated applications, including gas feed lines, crude oil, turbines, LNG, field gas or polymer factories, compressor or separator skids, and water tanks. Oil refinery feedstock lines, hydrocarbon processing, etc.
- Stainless steel ball valves are helpful in cooling water, petroleum refining, feed water, brewing, and desalination.
- High-pressure ball valves are ideal for use in underground, subsea, and cryogenic applications.
Cost
A ball valve is often more cost-effective than a plug valve. Ball valves are typically less expensive upfront, require lower maintenance costs due to their more straightforward design, and excel in quick on/off operations, making them versatile and efficient for various applications. However, the choice should be based on your needs, as plug valves may be preferred when precise flow control or operating conditions are essential. Ultimately, the decision hinges on your application requirements and the balance between initial costs, maintenance expenses, and operational efficiency.
Maintenance
Ball valves are generally easier to maintain than plug valves. Ball valves have a simple, robust design with fewer components, reducing the chances of wear and potential failures. Maintenance typically involves basic tasks such as lubrication and occasional seal replacement. In contrast, plug valves have a more intricate construction with a rotating plug, which can require more frequent and involved maintenance. This complexity can lead to higher maintenance costs and downtime. Therefore, ball valves often offer a more straightforward and cost-effective solution when it comes to ease of maintenance.
Life Span
Plug Valve: The plug valve handles more torque and has a larger surface area in contact with the flow medium. This means that the valves are subjected to additional wear and tear and are more prone to corrosion.
Control Capacity
Plug Valve: The significantly large amount of torque in the valve makes it difficult to open and close in high-pressure applications.
Ball Valve: Ball valves are operated by various actuators like pneumatic, manual, electric, hydraulic, etc. They work under high-pressure situations because they’re easy to close and open, requiring little force.
Customization Option
Plug Valve: Customization is only possible to a limited extent. This is due to their structure, leaving room for little advancement. The most common form is the Multi-port plug valve, which comes in sizes ranging from two to five ports.
Ball Valve: Ball valves allow considerable adjustment than plug valves. Because there are several types on the market, the personalized options vary. Unidirectional, bidirectional, and multidirectional ball valves are offered.
