While ball valves are the most commonly used valve compared to butterfly valves, choosing the correct valve can be confusing because ball valves come in all shapes and sizes. The structure of a ball valve consists of a stem, a valve body, a valve seat and, in some cases, a transmission.
The valve's actuator rotates the ball at different angles to prevent or allow fluid flow. Ball valves can be divided into two categories, full bore valves and reduced bore valves. Understanding the key differences between full and reduced bore valves is important in determining their application.
Full Bore Ball Valve
A full bore valve is a ball valve that opens fully when the actuator moves, creating a clear, unobstructed path for fluid to pass through the pipe that uses the valve.
Typically, in full port valves, the inside diameter of the ball is greater than 95% of the inside diameter of the ball valve port. The main difference between full bore ball valves and reduced bore ball valves is that the former has a smaller bore size compared to end connections.
In this type of ball valve, the size of the flow path from the inlet to the outlet remains consistent and does not change. Since the valve has a flow path of equal width, its diameter should not be too different from the nominal flow path diameter mentioned in the specification. For example, if the specified diameter of a full port valve is DN30, the flow path diameter should be close to 30.
Application
When comparing full bore ball valves and reduced bore ball valves, it is important to understand the application of both. Full port valves are available in pressure ratings from 150 to 600. Depending on their pressure rating, diameter and design, these ball valves are generally used in industries and pipelines where viscous media that are prone to slagging need to be conveyed.
Since full port valves provide unimpeded flow and have low fluid resistance, heavy fluids can flow more easily through pipes if these valves are used. A good example of the use of these valves is underground oil and gas pipelines.
Reduced Bore Ball Valve
The main difference between a reduced bore valve and a full bore valve is the size of the diameter. A reducing vlve is a ball valve with an opening smaller than the end connection. In this type of valve, the inside diameter of the ball is less than 85% of the inside diameter of the ball valve port.
Since the inlet is wider than the runner diameter, the actual diameter can be taken as one specification lower than the given parameter. For example, the flow path of a DN50 reducing valve will be around 38.
It is important to note that the opening of this ball valve is usually no larger than 9mm, although some manufacturers may create custom sizes depending on the application and expected load.
Application
When comparing a reduced bore ball valve with a full bore ball valve, the former has greater flow resistance. This makes it ideal for use with smaller pipelines that carry fluids to storage units such as tanks, especially in refining companies.
Considering the design and flow resistance of the reduced diameter ball valve, it is usually used in industrial pipelines that convey low viscosity media such as gas or water. Due to its slightly higher flow resistance compared to full port ball valves, it can significantly reduce the piping load as it can regulate the flow of lighter media. Hence, it promotes cost savings.
Comparison Between Ball Valve Full Port Vs Reduced Port
These two different ball valve types can be compared in terms of size, cost, and installation to determine their respective uses.
1. Installation
Reduced bore ball valves are smaller and therefore lighter in weight. Therefore, it is easier to install a reduced bore ball valve than a full bore valve. In fact, full-bore ball valves are nearly 30 percent heavier than reduced-bore ball valves, and therefore more bulky.
Due to easier installation and smaller size, reduced bore ball valves are ideal for situations where load reduction is necessary in pipelines, such as pipelines conveying gases or liquids like water.
2. Maintenance
Ease of maintenance is another important factor that can help determine the type of valve to use. In industries that do not have the resources to deal with regular cleaning of blocks and other maintenance issues, it is best to choose full bore ball valves versus reduced bore ball valves.
This is because the former allows fluid to flow unimpeded and last longer without regular maintenance. At the same time, if the pressure drop is large where the ball valve is required, it is best to use a full-bore valve.
In a reducing ball valve, extreme changes in pressure can seriously affect the way media is transferred from one end to the other. A constant pressure drop can bring the whole system down because the reducing ball valve cannot handle the pressure drop. However, full bore ball valves can easily handle two limbs without breaking.
3. Cost
Reduced bore ball valves are less expensive than full bore ball valves due to their smaller size and lighter weight. Cost also depends on the durability and performance of these two valves.
The full port ball valve is made of high quality material because it has to withstand higher pressure than similar products. It requires no regular maintenance and is not prone to collapse.
On the other hand, reducing bore ball valves are designed for steady pressure and require regular maintenance. They are easy to replace and cannot handle the same level of work that full port ball valves can.
4. Nature Of Work
The size of the piping network plays a key role in determining the type of ball valve used. Larger pipes are generally used to handle more viscous media. Because of their larger diameter and lower fluid resistance, full port valves can easily handle these viscous media, just like in a refinery.
On the other hand, if the pipeline network handles less viscous and lighter media, such as water, paraffin or gas, reducing bore ball valves are preferred. This applies to the fact that smaller pipes handle these media. Since they offer slightly more resistance than full port valves, they reduce overall operating costs.
Conclusion
To determine the type of ball valve that must be used, several factors must be considered, such as the nature of the job, pipe size, maintenance resources and budget. Both full and reduced bore valves have different applications. Therefore, neither one is better than the other.
Full bore valves are used for large diameter pipes that handle viscous media, while reduced bore valves are used for small diameter pipes that handle light, fast-flowing fluids.
