The difference between one piece, two piece and three piece ball valve

What is a one piece ball valve?

One piece ball valve is composed of ball, PTFE ring and lock nut. One plug can fix the ball. It is small in size, reliable in sealing, simple in structure and convenient in maintenance. One piece is of reduced diameter, and the actual flow diameter is smaller than the thread diameter.

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Advantages of one piece ball valve

  • 1. The fluid resistance is small, and its resistance coefficient is equal to that of the same length of pipe.
  • 2. Simple structure, small volume and light weight.
  • 3. It is compact and reliable. At present, the sealing surface material of ball valve is widely used with good sealing performance, and it has been widely used in vacuum system.
  • 4. It is easy to operate and fast to open and close. Only 90 ° rotation is needed from full opening to full closing, which is convenient for remote control.
  • 5. The maintenance is convenient, the ball valve structure is simple, the sealing ring is generally movable, and it is convenient to dismantle and replace.
  • 6. When the valve is fully open or closed, the sealing surfaces of the ball and valve seat are isolated from the medium, and the medium will not cause erosion of the valve sealing surface.
  • 7. Wide range of application, diameter from small to several millimeters, large to several meters, from high vacuum to high pressure. When the ball is rotated 90 degrees, the inlet and outlet should be spherical, so as to cut off the flow.

Application of one piece ball valve

One piece ball valve is a relatively new type of ball valve. It has some unique advantages of its own structure, such as no friction on the switch, no easy wear of seal and small opening and closing torque. This reduces the size of the actuator. Equipped with multi rotary electric actuator, the medium can be adjusted and cut off tightly. It is widely used in petrochemical city water supply and drainage, etc.

Working principle of one piece ball valve

The working principle of one piece ball valve is to make the valve unblocked or blocked by rotating the valve. The ball valve has the advantages of light switch, small volume, large diameter, reliable sealing, simple structure and convenient maintenance. The sealing surface and spherical surface are often in closed state and are not easy to be eroded by medium, so they are widely used in various industries.

Notes on one piece ball valve

One piece ball valve can be divided into straight through type, three-way type and right angle type according to its channel position. The latter two kinds of ball valves are used to distribute medium and change the flow direction of medium. The following points should be paid attention to in the installation and maintenance of type ball valve:

  • 1. Leave a position for the valve handle to rotate.
  • 2. It can not be used as throttling.
  • 3. The ball valve with transmission mechanism shall be installed vertically.

What is a two piece ball valve?

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Two piece ball valve is clamped by two pieces of valve body to fix the ball. The sealing effect is better than that of one piece ball valve. The maintenance is relatively complicated. The tightness of bolts in the middle is very important, which is related to whether there is leakage. Two piece ball valve is not suitable for high pressure.

Structure of two piece ball valve

The two piece ball valve can be divided into the following types according to the structure:

Floating ball valve

The ball of ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure the sealing of the outlet end. The floating ball valve has simple structure and good sealing performance, but the load of the ball bearing working medium is transferred to the outlet sealing ring, so whether the sealing ring material can withstand the working load of the ball medium should be considered. This structure is widely used in medium and low pressure ball valves.

Fixed ball valve

The ball of ball valve is fixed and does not move under pressure. Fixed ball valves are equipped with floating valve seat. Under the pressure of medium, the valve seat moves and the sealing ring is pressed tightly on the ball to ensure sealing. Usually, bearings are installed on the upper and lower shafts of the ball, and the operating torque is small, which is suitable for high pressure and large diameter valves. In order to reduce the operating torque of ball valves and increase the reliability of sealing, recently oil sealed ball valves have appeared. Special lubricating oil is injected between the sealing surfaces to form an oil film, which not only enhances the sealing performance, but also reduces the operating torque, which is more suitable for high pressure and large diameter ball valves.

Elastic ball valve

The ball of ball valve is elastic. Ball and valve seat seal ring are made of metal materials, the sealing specific pressure is very large, the pressure of medium itself can not meet the requirements of sealing, so external force must be applied. This valve is suitable for high temperature and high pressure medium. Elastic sphere is to obtain elasticity by opening an elastic groove at the lower end of the inner wall of the sphere. When the channel is closed, the wedge head of the valve stem is used to make the ball open and press the valve seat to achieve sealing. Before rotating the ball, loosen the wedge head first, and then the ball will return to its original shape, so that there is a small gap between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.

Advantages of two piece ball valve

Two piece ball valve is mainly used to cut off, distribute and change the flow direction of medium in the pipeline. Ball valve is a new type of valve which has been widely used in recent years.

  • 1. The fluid resistance is small, and its resistance coefficient is equal to that of the same length of pipe.
  • 2. Simple structure, small volume and light weight.
  • 3. It is compact and reliable. The sealing surface material of ball valve is widely used in plastic with good sealing performance, and it has been widely used in vacuum system.
  • 4. It is easy to operate and fast to open and close. Only 90 ° rotation is needed from full opening to full closing, which is convenient for remote control.
  • 5. The maintenance is convenient, the ball valve structure is simple, the sealing ring is generally movable, and it is convenient to dismantle and replace.
  • 6. When the valve is fully open or closed, the sealing surfaces of the ball and valve seat are isolated from the medium, and the medium will not cause erosion of the valve sealing surface.
  • 7. Wide range of application, diameter from small to several millimeters, large to several meters, from high vacuum to high pressure. When the ball is rotated 90 degrees, the inlet and outlet should be spherical, so as to cut off the flow.

The ball valve can be closed tightly with only 90 degree rotation and small rotation torque. The completely equal inner cavity of the valve body provides the medium with a small resistance and a straight flow path. It is generally considered that ball valve is most suitable for direct opening and closing, but in recent years, ball valve has been designed to throttle and control flow. The main characteristics of ball valve are its compact structure, easy operation and maintenance, suitable for water, solvent, acid, natural gas and other general working media, but also suitable for the working conditions of the media, such as oxygen, hydrogen peroxide, methane and ethylene. The valve body can be integral or combined.
Ball valve is a relatively new type of ball valve, which has some unique advantages of its own structure, such as switch without friction, seal is not easy to wear, opening and closing torque is small. This reduces the size of the actuator. Equipped with multi rotary electric actuator, the medium can be adjusted and cut off tightly. It is widely used in petroleum, chemical industry, urban water supply and drainage, etc.

Working principle of two piece ball valve

Its working principle is as follows:

Opening process

  • 1. In the closed position, the ball is pressed on the valve seat by the mechanical [wiki] pressure of the valve stem.
  • 2. When the handwheel is turned anticlockwise, the valve rod will move in reverse direction, and the angular plane at its bottom will make the ball break away from the valve seat.
  • 3. The valve stem continues to lift and interacts with the guide pin in the screw groove of the valve stem to make the ball rotate without friction.
  • 4. Until it reaches the full open position, the valve rod is lifted to the limit position, and the ball rotates to the full open position.

Closing process

  • 1. When closing, turn the hand wheel clockwise, the valve stem will start to drop and the ball will leave the valve seat and start to rotate.
  • 2. Continue to rotate the hand wheel, the valve rod is affected by the guide pin embedded in the screw groove on the hand wheel, so that the valve rod and the ball rotate 90 ° at the same time.
  • 3. Just before closing, the ball has rotated 90 ° without contact with the valve seat.
  • 4. In the last few turns of the hand wheel, the angular plane at the bottom of the valve rod is mechanically wedged to press the ball against the valve seat to achieve complete sealing.

Two piece ball valve can be divided into straight through type, three-way type and right angle type according to its channel position. The latter two kinds of ball valves are used to distribute medium and change the flow direction of medium. The following points should be paid attention to during the installation and maintenance of two-piece ball valve:

  • 1. Leave a position for the valve handle to rotate.
  • 2. It can not be used as throttling.
  • 3. The ball valve with transmission mechanism shall be installed vertically.

The working principle of two-piece ball valve is to make the valve unblocked or blocked by rotating the valve.

The ball valve has the advantages of light switch, small volume, large diameter, reliable sealing, simple structure and convenient maintenance. The sealing surface and spherical surface are often in closed state and are not easy to be eroded by medium, so they are widely used in various industries.
The two-piece ball valve is mainly used to cut off, distribute and change the flow direction of medium in the pipeline.

What is a three piece ball valve?

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The three piece ball valve is similar to the two piece ball valve, but there is an additional valve body in the middle of the ball, which is clamped by the welding neck flange on both sides. Different from two piece ball valve and one piece ball valve, three piece ball valve is easy to disassemble and maintain.

Advantages of three piece ball valve

The three piece ball valve has the following advantages:

  • 1. The fluid resistance is small, and its resistance coefficient is equal to that of the same length of pipe.
  • 2. Simple structure, small volume and light weight.
  • 3. It is compact and reliable. The sealing surface material of ball valve is widely used in plastic and has good sealing performance. It has also been widely used in vacuum system.
  • 4. It is easy to operate and fast to open and close. Only 90 ° rotation is needed from full opening to full closing, which is convenient for remote control.
  • 5. The maintenance is convenient, the ball valve structure is simple, the sealing ring is generally movable, and it is convenient to dismantle and replace.
  • 6. When the valve is fully open or closed, the sealing surfaces of the ball and valve seat are isolated from the medium, and the medium will not cause erosion of the valve sealing surface.
  • 7. Wide range of application, diameter from small to several millimeters, large to several meters, from high vacuum to high pressure. Flange ball valve, flange gate valve, knife gate valve.

Differences between one piece stainless steel ball valve and two piece three piece ball valve:

First of all, a piece of ball valve is a manual valve, and its structure design is integral. The ball is stabilized by a plug, so that it can be convenient for maintenance. Moreover, the diameter of the ball valve is small. When the ball is put in from one side of the valve body, the valve seat should be screwed in before pressing the ball. Some non-standard one-piece ball valve has short structure, so the best way to distinguish is the structure of the valve body.
The difference between one-piece ball valve and two-piece and three-piece ball valve lies in the flow rate. The internal design structure of one-piece ball valve belongs to necking design. The flow rate of one-piece ball valve with the same caliber is much smaller than that of other two kinds of ball valves.
One piece ball valve has the advantages of low cost and low price.
One piece ball valve is fixed by a plug. It is easy to maintain and practical. It is often used in small size valves.
Two piece ball valve is called stainless steel ball valve. It is composed of left and right valve body bolts. When fixing, two pieces of valve body are used to clamp the ball valve. However, maintenance is relatively difficult. The most important thing is to see the tightness of the screw in the middle, which is directly related to whether the sealing is tight. In addition, it is mainly used in atmospheric and high pressure environment, such as non-standard nominal diameter below DN50 also belongs to two-piece valve. The two-piece ball valve is fixed by two pieces of valve body, and the two-piece ball valve has excellent compression resistance and flow rate.
Two piece ball valve is fixed by two pieces of valve body, the maintenance is more complex, the middle screw tightness is very important, the relationship between whether air leakage, commonly used valve.
The three piece ball valve is similar to the two piece ball valve, but the three piece ball valve can be used in ultra-high pressure environment, and the structure design of the valve will have three pieces of valve body, which are clamped and fixed by the left and right flange with neck, and the normal nominal diameter is above DN50.
Three piece ball valve is similar to two pieces, but there are many valve bodies in the middle of the ball, which are clamped by two necked flanges. Large and important valves are commonly used.

The biggest feature of the three piece ball valve design structure is convenient installation. Since the three piece ball valve can be disassembled and installed by itself during installation, even some other connection methods in different pipelines are completely OK, such as flange, quick installation, thread, welding, etc., so the most complete connection mode on the market is three piece ball valve, especially when welding is required that the two-piece ball valve can not be disassembled and installed, if you want to weld on the pipe, it will be easy to burn out the PTFE (similar to plastic) internals. At this time, the best choice is three piece ball valve.

Source: China Valve Manufacturer – Yaang Pipe Industry Co., Limited (www.metallicsteel.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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the difference between one piece two piece and three piece ball valve - The difference between one piece, two piece and three piece ball valve
Article Name
The difference between one piece, two piece and three piece ball valve
Description
Three piece ball valve is similar to two pieces, but there are many valve bodies in the middle of the ball, which are clamped by two necked flanges. Large and important valves are commonly used.
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www.metallicsteel.com
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