Causes for Internal Leakage of the Electric Forged Steel Ball Valve & Its Solutions
Dec 09, 2020
Electric forged steel ball valves have been more and more widely used in various industrial control systems due to its advantages of high control accuracy, convenient installation and adjustment. However, there are also some problems that bug the on-site installation and adjustment personnel in the process of use, that is, the problem of internal valve leakage. Causes for the common internal leakage of the electric forged steel ball valves and its solutions are discussed in this article, hoping to help the factory's on-site maintenance personnel.
1. The zero position setting of the electric forged steel ball valve actuator being not accurate, and the valve's full closed position being not reached
Adjustment methods are as the following:
1. The zero position setting of the electric forged steel ball valve actuator being not accurate, and the valve's full closed position being not reached
Adjustment methods are as the following:
- Manually close the valve well (You must confirm that it has been completely closed).
- Manually close the valve with a greater force again until it can't be turned.
- Turn back with half a turn (a valve opening direction).
- Then adjust the limit.
2. Selection of stroke modes of electric forged steel ball valves
The electric forged steel ball valve is opened and closed by rotating 90°. The torque of the actuator is not large enough. When there is no pressure, it is easy to reach the fully closed position. When there is rotational force, the thrust of the liquid cannot be overcome, so the closed position is not in place.
Solutions: Replace an actuator with larger thrust, or a balanced spool is replaced to the unbalanced force of the medium.
3. Internal leakage caused by manufacturing quality of the electric forged steel ball valve
The valve manufacturer does not strictly control the valve material, processing technology, assembly process, etc. during the production process, resulting in unqualified sealing surface grinding. Pitting, sand holes and other defective products are not completely eliminated, resulting in internal leakage of the electric forged steel ball valve.
Solutions: Reprocess the sealing surface.
4. The control part of the electric forged steel ball valve affecting the internal leakage of the valve
The traditional control method of electric forged steel ball valves is through mechanical control methods such as valve limit switches and over torque switches. Because these control elements are affected by environmental temperature, pressure and humidity, the valve positioning is inaccurate. Objective factors such as spring fatigue and uneven thermal expansion coefficient cause internal leakage of the electric forged steel ball valve.
Solutions: Readjust the limit.
5. Internal leakage caused by debugging of electric forged steel ball valves
The electric forged steel ball valve generally cannot be electrically opened after manual closing due to the influence of the processing and assembly process. If the stroke of the electric control valve is adjusted smaller by the upper and lower limit switches, the electric control valve will not be fully closed or opened. However, if the stroke of the electric forged steel ball valve is adjusted larger, the over torque switch protection action will be caused. If the action value of the over torque switch is adjusted larger, the deceleration transmission or valve will be damaged, or even burn the motor. In order to solve this problem, usually, when the electric control valve is debugged, the electric control valve is manually turned to the end, and then turn one circle in the open direction to set the lower limit switch position of the electric door. Open the electric forged steel ball valve to the fully opened position, the upper limit switch position, so that not being able to be opened electrically after manual closing won’t happen for the electric forged steel ball valve and the electric door can be opened and closed freely. However, the internal leakage of the electric forged steel ball valve is caused virtually. Even if the adjustment of the electric control valve is ideal, the operating position of the limit switch is relatively fixed, and the continuous scouring and wear of the valve control medium during operation will cause the internal leakage of the valve due to the loose closing of the valve.
Solutions: Readjust the limit.
6. Internal leakage of electric control valve due to cavitation corrosion caused by wrong selection of electric forged steel ball valves
Cavitation is related to the pressure difference. When the actual pressure difference of the valve △P is greater than the critical pressure difference △Pc for cavitation, cavitation occurs. During the cavitation process, the bubble bursts and releases great energy, which has a great destructive effect on throttling elements such as the valve seat and valve spool. The common valve can be used for three months or even less under cavitation conditions. The valve has suffered severe cavitation corrosion, resulting in valve seat leakage as high as 30 % of rated flows, which is irreparable. Therefore, electric forged steel ball valves for different purposes have different specific technical requirements. It is very important to reasonably choose the electric control valve according to the system process.
7. Internal leakage caused by flushing of media and the aging of the electric forged steel ball valve
After the electric forged steel ball valve is adjusted and operated for a certain period of time, wear occurs between the valve spool and valve seat and internal components age due to the cavitation of the valve and the flushing of the medium. The large stroke of the electric control valve will appear and the electric control valve can not be closed fully, resulting in increased leakage of the electric control valve. As time goes by, the internal leakage of the electric forged steel ball valve will become more and more serious.
Solutions: Readjust the actuator and perform regular maintenance and calibration.
The electric forged steel ball valve is opened and closed by rotating 90°. The torque of the actuator is not large enough. When there is no pressure, it is easy to reach the fully closed position. When there is rotational force, the thrust of the liquid cannot be overcome, so the closed position is not in place.
Solutions: Replace an actuator with larger thrust, or a balanced spool is replaced to the unbalanced force of the medium.
3. Internal leakage caused by manufacturing quality of the electric forged steel ball valve
The valve manufacturer does not strictly control the valve material, processing technology, assembly process, etc. during the production process, resulting in unqualified sealing surface grinding. Pitting, sand holes and other defective products are not completely eliminated, resulting in internal leakage of the electric forged steel ball valve.
Solutions: Reprocess the sealing surface.
4. The control part of the electric forged steel ball valve affecting the internal leakage of the valve
The traditional control method of electric forged steel ball valves is through mechanical control methods such as valve limit switches and over torque switches. Because these control elements are affected by environmental temperature, pressure and humidity, the valve positioning is inaccurate. Objective factors such as spring fatigue and uneven thermal expansion coefficient cause internal leakage of the electric forged steel ball valve.
Solutions: Readjust the limit.
5. Internal leakage caused by debugging of electric forged steel ball valves
The electric forged steel ball valve generally cannot be electrically opened after manual closing due to the influence of the processing and assembly process. If the stroke of the electric control valve is adjusted smaller by the upper and lower limit switches, the electric control valve will not be fully closed or opened. However, if the stroke of the electric forged steel ball valve is adjusted larger, the over torque switch protection action will be caused. If the action value of the over torque switch is adjusted larger, the deceleration transmission or valve will be damaged, or even burn the motor. In order to solve this problem, usually, when the electric control valve is debugged, the electric control valve is manually turned to the end, and then turn one circle in the open direction to set the lower limit switch position of the electric door. Open the electric forged steel ball valve to the fully opened position, the upper limit switch position, so that not being able to be opened electrically after manual closing won’t happen for the electric forged steel ball valve and the electric door can be opened and closed freely. However, the internal leakage of the electric forged steel ball valve is caused virtually. Even if the adjustment of the electric control valve is ideal, the operating position of the limit switch is relatively fixed, and the continuous scouring and wear of the valve control medium during operation will cause the internal leakage of the valve due to the loose closing of the valve.
Solutions: Readjust the limit.
6. Internal leakage of electric control valve due to cavitation corrosion caused by wrong selection of electric forged steel ball valves
Cavitation is related to the pressure difference. When the actual pressure difference of the valve △P is greater than the critical pressure difference △Pc for cavitation, cavitation occurs. During the cavitation process, the bubble bursts and releases great energy, which has a great destructive effect on throttling elements such as the valve seat and valve spool. The common valve can be used for three months or even less under cavitation conditions. The valve has suffered severe cavitation corrosion, resulting in valve seat leakage as high as 30 % of rated flows, which is irreparable. Therefore, electric forged steel ball valves for different purposes have different specific technical requirements. It is very important to reasonably choose the electric control valve according to the system process.
7. Internal leakage caused by flushing of media and the aging of the electric forged steel ball valve
After the electric forged steel ball valve is adjusted and operated for a certain period of time, wear occurs between the valve spool and valve seat and internal components age due to the cavitation of the valve and the flushing of the medium. The large stroke of the electric control valve will appear and the electric control valve can not be closed fully, resulting in increased leakage of the electric control valve. As time goes by, the internal leakage of the electric forged steel ball valve will become more and more serious.
Solutions: Readjust the actuator and perform regular maintenance and calibration.
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