A one-piece ball valve means a single-piece ball valve. The end connections and the body are formed from a single piece of material. The clarity of this design component makes it lower cost than the other versions.
The single piece ball valve has a complex cast body which lowers the risk of leakage. This structure gives a reduced number of opportunities for leakage. The valve seals and trim are added through one of the end connections. Once the valve is placed, it can only run by removing the entire valve assembly from the piping system. One-piece ball valves are generally not repaired and are inexpensive.
In contrast, two-piece ball valves consist of two separate pieces. One piece has one end connection and the body. The second piece fits into the first, keeps, and includes the second-end connection. They have a second piece that fits into the first, giving the second-end reference.
The structure presents a different leak potential where the two parts are joined. In contrast with a one-piece, they also allow break up for internal replacement. These valves can show bidirectional flow shutoff and full port service.
This article will teach you about the one-piece or two-piece ball valve. So, let’s explore them.
What is a one-piece ball, and what is a two-piece ball?
A one-piece ball valve features only one body part. They have different port sizes than the line. One-piece ball valves are offered only in reduced or smaller port sizes than the pipe size. There are better choices for applications where the flow rate is a significant point.
But, this type of valve can not be replaced or is irreparable. Its flow diameter is smaller than the thread diameter.
Advantages of Using a One-Piece Ball Valve
- It gives less fluid resistance and zero friction on the switch.
- Its coefficient of resistance is similar to that of the same length of pipe.
- It is easy to work with and has a quick opening or closing due to rotation.
- It is lightweight and takes up tiny space in a piping system.
- The sealing surface material is used with good sealing performance.
- They are easy to maintain as their structure is simple. The sealing ring is movable and convenient to replace and dismantle.
Because it is a new type of ball valve, it offers some unique features and lowers the size of the actuator. The working principle of a one-piece ball valve is to block the valve or unblock it by rotating it.
The working principle of one piece & two piece ball valve
The working principle of the one-piece ball valve is the automatic pressure of the valve stem. But a two-piece ball valve allows the valve to be blocked or unblocked by rotating the valve.
The valve body of the ball valve is different
The design of the one-piece ball valve is a manual valve. The diameter of the ball valve is small. The ball is put in from one side of the valve body after the valve seat is screwed in, then presses the ball. The two-piece ball valve is clamped, but the maintenance is a little challenging.
The closing parts of the ball valve are different
In a one-piece ball valve, the closing piece is a sphere; the ball rotates around the centerline to open and close a valve. In contrast, a two-piece ball valve has no special requirements for moving.
Two-piece valve
A two-piece ball valve has two free elements connecting them through a bolt or thread. Since in this valve body, two separate sections are combined. It is used to distribute, cut off and change the flow direction of the medium in the pipeline.
As a result, more than a two-piece ball valve is needed for high-pressure systems. Unlike a one-piece valve, it is easy to disassemble it for internal component repair. Its sealing effect is better than a one-piece ball valve.
Structure Of Two-piece Ball Valve
According to the structure, a two-piece ball valve can be divided into the following types:
Floating ball valve
The ball valve is free floating. Floating the ball can press on the sealing surface to allow the sealing of the outlet end. The floating ball valve has good sealing performance with a simple structure. But the load of the ball bearing medium is transferred to the outlet sealing ring. This device is often used in low-pressure medium ball valves.
Fixed ball valve
Some two-piece ball valves have been fixed, and not moving the ball valves under pressure. They are designed with floating valve seats. Due to the pressure medium, the valve seat moves, and the sealing ring is pressed on the ball to allow sealing. Often, bearings are placed on the lower and upper shafts of the ball. And small operating torque is suitable for large diameters and high pressure. They are ideal for large-diameter and high-pressure ball valves.
Elastic ball valve
In the type of two-piece ball valve, the ball is elastic. The valve seat and ball seal ring are metal materials with significant pressure. This type of valve is helpful for high-pressure and high-temperature mediums.
Working Principle Of Two-piece Ball Valve
Let’s explore the working principle of a two-piece ball valve:
Opening process
- The ball is pressed on the valve seat by applying pressure on the valve stem in the closed position.
- The valve rod will move in reverse when the handwheel is rotated anti-clockwise. This movement at its bottom will make the ball break away from the valve seat.
- The valve stem continues to interact with the pin in the screw of the valve stem to allow the ball to rotate.
- The valve rod is lifted to the limit position until the ball reaches the fully open position.
Closing Process
For closing, rotate the hand wheel clockwise. The valve stem will start to drop, and the ball will leave the valve seat.
- Continue to rotate the hand wheel so that the valve rod and the ball rotate 90 degrees.
- Before closing, rotate the ball at 90 ° without contact with the valve seat.
- The bottom of the valve rod is wedged to press the ball against the valve seat to get complete sealing.
Tips for installing a two-piece ball valve
You should notice some points during the maintenance and installation of the two-piece ball valve.
- Leave a position for the valve handle to turn.
- It can’t be used for throttling.
- You must install a ball valve with a transmission mechanism perpendicularly.
- Advantages of two-piece ball valve
- The ball valve has a small volume, large diameter, better sealing, and simple structure.
- The medium doesn’t quickly erode the spherical surfaces in closed conditions.
- It gives small fluid resistance whose coefficient is equal to the same length of a pipe.
- Its design provides good sealing performance.
- Its structure is more accessible to repair than a one-piece ball valve.
- There is no corrosion because the sealing and valve seat are isolated from the medium.
It requires only a 90 degrees turn to open or close, so easy for the remote control.
The two-piece ball valve is used to cut off and change the flow direction in the pipeline.
A two-piece ball valve is often used in many applications. Ease of maintenance in a wide range of industries. Some industries using a two-piece ball valve include food, manufacturing, and automotive.
Why is there a pressure difference between a one piece ball and a two-piece ball?
The one-piece ball is mostly low-pressure PN16. And two-piece ball valve is from low pressure to high pressure, PN16-PN100, with a wide range of options.
This assembly type gives two-piece ball valves with a port size equal to the line pipes. Since the flow rate can be much higher on a complete port valve, the two-piece valves can hold pressures from both sides, making them practical for two-directional flow shutoff. Two-piece ball valves are often the most cost-efficient complete port valve on today’s market.
What is the flow capacity difference between one-piece and two-piece balls?
The one-piece ball valve is narrowed, such as DN25, and the actual diameter of the ball core flow channel is about 15mm. The two-piece type is a full through-flow channel size DN25. The ball core flow channel is also 25mm.
1- and 2-piece ball valves are popularly used in industries wherever on/off fluid control is needed. The most common use include chemical, pharmaceutical, food, and agricultural sectors.
While either type of ball valve is helpful for many applications, only 1- or 2-piece ball valves should be used in high-cycle or high-pressure systems that need maintenance. One-piece ball valves are not repaired. While 2-piece is possible, attempting to rebuild and reinstall is.
Summary
One- and two-piece ball valves are the most common types used where on/off fluid control is needed. The 1-piece Ball valve consists of a single, solid body and is impossible to repair. They have different port sizes. While in the case of a 2-piece ball valve, allow fixing. They have a complete port configuration. They contain two separate pieces, connecting through a bolt and flanged assembly. We hope you understand well the differences in 1or 2-piece ball valves. If you have any questions feel free to contact us.
