The main classifications of cast steel ball valves
Addtime：2022-12-31 From： View：447
Introduction:
The cast steel ball valve was invented in the 1950s. With the rapid development of science and technology and continuous improvements in production processes and product structures, within just 40 years, it has rapidly become one of the main types of valves. In developed industrial countries in the West, the usage of ball valves is increasing year by year. In China, ball valves are widely used in industries such as petroleum refining, long-distance pipelines, chemical engineering, papermaking, pharmaceuticals, water conservancy, power, municipal services, and steel manufacturing. They hold a crucial position in the national economy.
Main Categories:
According to the structural form
1. Floating Ball Valve
The ball of the ball valve is floating. Under the pressure of the medium, the ball can produce a certain displacement and tightly press against the sealing surface at the outlet end, ensuring the sealing at the outlet.
The floating ball valve has a simple structure and good sealing performance. However, the load of the working medium is entirely transferred to the outlet sealing ring by the ball. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the ball. This structure is widely used in medium and low-pressure ball valves.
II. Fixed Ball Valve
The ball of a ball valve is fixed and does not move when under pressure. Fixed ball valves are all equipped with floating valve seats. When subjected to the pressure of the medium, the valve seat moves, causing the sealing ring to tightly press against the ball, ensuring a seal. Usually, bearings are installed on the upper and lower shafts of the ball, resulting in a small operating torque and making them suitable for high-pressure and large-diameter valves.
In order to reduce the operating torque of the ball valve and enhance the reliability of the seal, oil-sealed ball valves have emerged in recent years. They inject specially formulated lubricating oil between the sealing surfaces to form an oil film, which not only improves the sealing performance but also reduces the operating torque. They are particularly suitable for high-pressure and large-diameter ball valves.
III. Elastic Ball Valve
The ball of the ball valve is elastic. Both the ball and the valve seat sealing ring are made of metal materials. The sealing pressure is very high. The sealing requirement cannot be met by the pressure of the medium itself; an external force must be applied. This type of valve is suitable for high-temperature and high-pressure media.
The elastic sphere is made by opening an elastic groove at the lower end of the inner wall of the sphere to achieve elasticity. When the passage is closed, the wedge-shaped head of the valve stem is used to expand the sphere and press it against the valve seat to achieve sealing. Before rotating the sphere, the wedge-shaped head is loosened first, and then the sphere returns to its original shape, creating a very small gap between the sphere and the valve seat, which can reduce the friction on the sealing surface and the operating torque.
According to the position of the channel
Ball valves can be classified by their channel positions as straight-through type, three-way type and right-angle type. The latter two types of ball valves are used for distributing the medium and changing the direction of the medium flow.
Other Categories
Ball valves are classified into O-type ball valves and V-type ball valves. The O-type ball valve adopts a floating structure, with the ball core being a precision cast piece, and its surface is treated with hard chromium plating. The valve seat is made of reinforced polytetrafluoroethylene material. The flow passage is the same as the pipe diameter, resulting in extremely high flow capacity and very low resistance. It has no leakage when closed. It is generally used as a control valve and is particularly suitable for high-viscosity, fiber-containing, and granular media. The V-type ball valve adopts a fixed structure, with a V-shaped notch on the ball core, enabling proportional regulation. The flow characteristic is approximately equal percentage.
Depending on the type of process equipment, pneumatic or electric options can be chosen. They can be combined to form pneumatic ball valves and electric ball valves. For pneumatic ball valves, a valve positioner is required if proportional regulation is to be achieved. For electric ball valves, an electronic electric actuator or a servo amplifier, etc. must be selected if proportional regulation is to be realized.
In terms of material, they can be classified as: carbon steel ball valves, stainless steel 304 ball valves, 316 ball valves and copper ball valves.
In terms of application, they can be classified as: high-pressure ball valves and low-pressure ball valves.
High-pressure ball valve: Mainly applied in industries such as petroleum, natural gas, hydraulic oil, and construction machinery.
Low-pressure ball valve: Mainly used in pipelines where the medium is water or other non-corrosive substances.
The cast steel ball valve was invented in the 1950s. With the rapid development of science and technology and continuous improvements in production processes and product structures, within just 40 years, it has rapidly become one of the main types of valves. In developed industrial countries in the West, the usage of ball valves is increasing year by year. In China, ball valves are widely used in industries such as petroleum refining, long-distance pipelines, chemical engineering, papermaking, pharmaceuticals, water conservancy, power, municipal services, and steel manufacturing. They hold a crucial position in the national economy.
Main Categories:
According to the structural form
1. Floating Ball Valve
The ball of the ball valve is floating. Under the pressure of the medium, the ball can produce a certain displacement and tightly press against the sealing surface at the outlet end, ensuring the sealing at the outlet.
The floating ball valve has a simple structure and good sealing performance. However, the load of the working medium is entirely transferred to the outlet sealing ring by the ball. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the ball. This structure is widely used in medium and low-pressure ball valves.
II. Fixed Ball Valve
The ball of a ball valve is fixed and does not move when under pressure. Fixed ball valves are all equipped with floating valve seats. When subjected to the pressure of the medium, the valve seat moves, causing the sealing ring to tightly press against the ball, ensuring a seal. Usually, bearings are installed on the upper and lower shafts of the ball, resulting in a small operating torque and making them suitable for high-pressure and large-diameter valves.
In order to reduce the operating torque of the ball valve and enhance the reliability of the seal, oil-sealed ball valves have emerged in recent years. They inject specially formulated lubricating oil between the sealing surfaces to form an oil film, which not only improves the sealing performance but also reduces the operating torque. They are particularly suitable for high-pressure and large-diameter ball valves.
III. Elastic Ball Valve
The ball of the ball valve is elastic. Both the ball and the valve seat sealing ring are made of metal materials. The sealing pressure is very high. The sealing requirement cannot be met by the pressure of the medium itself; an external force must be applied. This type of valve is suitable for high-temperature and high-pressure media.
The elastic sphere is made by opening an elastic groove at the lower end of the inner wall of the sphere to achieve elasticity. When the passage is closed, the wedge-shaped head of the valve stem is used to expand the sphere and press it against the valve seat to achieve sealing. Before rotating the sphere, the wedge-shaped head is loosened first, and then the sphere returns to its original shape, creating a very small gap between the sphere and the valve seat, which can reduce the friction on the sealing surface and the operating torque.
According to the position of the channel
Ball valves can be classified by their channel positions as straight-through type, three-way type and right-angle type. The latter two types of ball valves are used for distributing the medium and changing the direction of the medium flow.
Other Categories
Ball valves are classified into O-type ball valves and V-type ball valves. The O-type ball valve adopts a floating structure, with the ball core being a precision cast piece, and its surface is treated with hard chromium plating. The valve seat is made of reinforced polytetrafluoroethylene material. The flow passage is the same as the pipe diameter, resulting in extremely high flow capacity and very low resistance. It has no leakage when closed. It is generally used as a control valve and is particularly suitable for high-viscosity, fiber-containing, and granular media. The V-type ball valve adopts a fixed structure, with a V-shaped notch on the ball core, enabling proportional regulation. The flow characteristic is approximately equal percentage.
Depending on the type of process equipment, pneumatic or electric options can be chosen. They can be combined to form pneumatic ball valves and electric ball valves. For pneumatic ball valves, a valve positioner is required if proportional regulation is to be achieved. For electric ball valves, an electronic electric actuator or a servo amplifier, etc. must be selected if proportional regulation is to be realized.
In terms of material, they can be classified as: carbon steel ball valves, stainless steel 304 ball valves, 316 ball valves and copper ball valves.
In terms of application, they can be classified as: high-pressure ball valves and low-pressure ball valves.
High-pressure ball valve: Mainly applied in industries such as petroleum, natural gas, hydraulic oil, and construction machinery.
Low-pressure ball valve: Mainly used in pipelines where the medium is water or other non-corrosive substances.