A valve is a control component in the fluid transportation system, which has the functions of cutting off, regulation, diversion, prevention of countercurrent, pressure stabilization, shunt and adjustment of medium flow balance.
A valve is also one of the most typical equipment in the heat system. The quality of the valve and whether to select a reasonable type according to the characteristics of valves will play a decisive role in the supply heat quality.
As the valves are laid in the ground well, it is not easy to detect the phenomenon of running, emitting, dripping and leaking. Generally, it can be found only when the user complains or the patrol inspector finds out the equipment is damaged. If there is a problem that cannot be found in time, it is not a small problem.
Today, we'd like to sort out the installation and maintenance of a ball valve which is a very common valve in the heat system.
By understanding the working principle and product characteristics of the valve, as well as the operation method and troubleshooting, we can make the relevant production operation system in the normal production of the company to ensure the safe operation of the valve equipment.
Working sealing principles of heated welding ball valves
The commonly used fully-welded ball valve and common flange ball valve are mainly composed of valve bodies, valve seats, balls, valve stems and transmission devices. The main function is to connect and cut off the fluid passage in the pipeline. Ball valves are driven by the transmission device to rotate the ball by 90 degrees to achieve the switch function. The main structure is divided into the floating ball structure and fixed ball structure.
Floating ball structure
The ball of floating ball valves in the valve body can be floated. Under the pressure of fluid medium, the ball is tightly pressed to the sealing valve seat of the outlet section, which will form a single seal, and the sealing of the front valve seat cannot be guaranteed. The ball valve with this structure is characterized by simple structure, simple manufacturing and good unilateral sealing performance, which is generally suitable for small diameter valves with diameters below DN300.
Fixed ball valve structure
The ball of the fixed structure has upper and lower rotating shafts. The lower part of the ball is inlaid with bearings, which is fixed by the lower valve stem. The upper part is connected with the upper valve stem. The ball can only rotate along the vertical axis of the valve channel, and can not move to one side like the floating ball valve.
Therefore, when the fixed ball valve works, the pressure of the fluid in front of the valve can only be transmitted to the valve stem and bearing. And there will be no pressure on the valve seat. Therefore, the valve seat will not deform due to the pressure change in the pipeline. It has good sealing performance and long service life.
Maintenance and management technology of heated ball valves
The correct use, installation and maintenance of ball valves are very important. Scientific management and maintenance of ball valves during the construction period can not only ensure safety, but also reduce the cost of construction and operation management periods.
The following aspects should be paid attention to:
1. The valve should be loaded and unloaded in a correct way to avoid mechanical damage to the valve. When lifting the valve, the lifting belt should not be tied to the valve stem or actuator for hoisting. If the valve is operated illegally, the valve stem will be bent; the valve stem seal will be invalid and the turbine box will be damaged.
2. Before the valve leaves the factory, blind plates or bonnets should be sealed at both ends of the valve to avoid water, sand, and other impurities in the process of transportation and construction sites from entering the valve chambers, causing damage and corrosion to the seal.
3. In the construction site, the valves should be placed in order. That's to say, it should not be placed randomly. If so, it will cause the drain valve or grease injection valve to break. The valve seat should be welded in the full face before welding, and the welding temperature should be controlled at 140℃ before welding.
4. Before the welding construction of fully-welded ball valves, it should be confirmed that the valve is welded in the full open position, so as to avoid the damage of the ball caused by welding spatter and scratch the sealing surface. The welding temperature of the valve seat should be controlled at 140 ℃.
5. After the hydraulic test, the water in the valve chamber should be drained to prevent corrosion and icing.
A valve is also one of the most typical equipment in the heat system. The quality of the valve and whether to select a reasonable type according to the characteristics of valves will play a decisive role in the supply heat quality.
As the valves are laid in the ground well, it is not easy to detect the phenomenon of running, emitting, dripping and leaking. Generally, it can be found only when the user complains or the patrol inspector finds out the equipment is damaged. If there is a problem that cannot be found in time, it is not a small problem.
Today, we'd like to sort out the installation and maintenance of a ball valve which is a very common valve in the heat system.
By understanding the working principle and product characteristics of the valve, as well as the operation method and troubleshooting, we can make the relevant production operation system in the normal production of the company to ensure the safe operation of the valve equipment.
Working sealing principles of heated welding ball valves
The commonly used fully-welded ball valve and common flange ball valve are mainly composed of valve bodies, valve seats, balls, valve stems and transmission devices. The main function is to connect and cut off the fluid passage in the pipeline. Ball valves are driven by the transmission device to rotate the ball by 90 degrees to achieve the switch function. The main structure is divided into the floating ball structure and fixed ball structure.
Floating ball structure
The ball of floating ball valves in the valve body can be floated. Under the pressure of fluid medium, the ball is tightly pressed to the sealing valve seat of the outlet section, which will form a single seal, and the sealing of the front valve seat cannot be guaranteed. The ball valve with this structure is characterized by simple structure, simple manufacturing and good unilateral sealing performance, which is generally suitable for small diameter valves with diameters below DN300.
Fixed ball valve structure
The ball of the fixed structure has upper and lower rotating shafts. The lower part of the ball is inlaid with bearings, which is fixed by the lower valve stem. The upper part is connected with the upper valve stem. The ball can only rotate along the vertical axis of the valve channel, and can not move to one side like the floating ball valve.
Therefore, when the fixed ball valve works, the pressure of the fluid in front of the valve can only be transmitted to the valve stem and bearing. And there will be no pressure on the valve seat. Therefore, the valve seat will not deform due to the pressure change in the pipeline. It has good sealing performance and long service life.
Maintenance and management technology of heated ball valves
The correct use, installation and maintenance of ball valves are very important. Scientific management and maintenance of ball valves during the construction period can not only ensure safety, but also reduce the cost of construction and operation management periods.
The following aspects should be paid attention to:
1. The valve should be loaded and unloaded in a correct way to avoid mechanical damage to the valve. When lifting the valve, the lifting belt should not be tied to the valve stem or actuator for hoisting. If the valve is operated illegally, the valve stem will be bent; the valve stem seal will be invalid and the turbine box will be damaged.
2. Before the valve leaves the factory, blind plates or bonnets should be sealed at both ends of the valve to avoid water, sand, and other impurities in the process of transportation and construction sites from entering the valve chambers, causing damage and corrosion to the seal.
3. In the construction site, the valves should be placed in order. That's to say, it should not be placed randomly. If so, it will cause the drain valve or grease injection valve to break. The valve seat should be welded in the full face before welding, and the welding temperature should be controlled at 140℃ before welding.
4. Before the welding construction of fully-welded ball valves, it should be confirmed that the valve is welded in the full open position, so as to avoid the damage of the ball caused by welding spatter and scratch the sealing surface. The welding temperature of the valve seat should be controlled at 140 ℃.
5. After the hydraulic test, the water in the valve chamber should be drained to prevent corrosion and icing.
Next: An Introduction to Stainless Steel Ball Valves
Previous: Notes for Quick Installation of Ball Valves
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