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How to use valves correctly is a knowledge that users must master. Only by using them correctly can they be used for a longer time. Therefore, the Hydraulic Control Valve Center recommends that everyone carefully read the user manual before installing and using valves, and strictly follow the valve's user manual for operation and maintenance. Negligence and recklessness are one of the main reasons for valve damage.
We know that the maintenance workload required for most valves is minimal, which means that most valves do not need to be repaired frequently. Sometimes, even small issues like valve stem leakage can become major problems due to negligence. Moreover, some reckless operators fail to close valves according to technical specifications, resulting in bent valve stems or severe damage to the closing components. Such situations occur from time to time.
The threaded joint between the valve stem nut and the valve stem should be regularly lubricated with lubricating oil, which can not only reduce the friction between them, but also extend their service life. This is also a very important protective measure. If the worn valve stem nut is still in use, it may break, causing the entire axial force of the valve stem to be unsupported and the valve to lose its function.
At the beginning of the gasket, there is a simple leakage, which eventually leads to the danger of steam leakage. To avoid this danger, the valve cover bolts should be tightened appropriately at the beginning of the leak; If the sealing surface of the valve seat is not properly selected, there may be a small amount of leakage at the beginning, and later it may expand to groove leakage, and there may be insufficient opening height, which accelerates the erosion of the fluid and leads to complete damage to the valve seat.
The reason for the bending of the valve stem may be due to the operator turning the handwheel excessively after closing the valve.
There are multiple reasons for valve damage. In fact, with some training for operators, similar situations may be avoided.
Now, we will explain the use, maintenance, and repair of several common valves one by one.
Globe valve is a commonly used shut-off valve, mainly used to connect or cut off the medium in the pipeline. In the pipeline system, the time when the shut-off valve is not operated is very short, so regular maintenance is necessary.
A small amount of packing leakage can be solved by simply tightening the packing gland nut. But when the packing is damaged, it must be replaced. When replacing the packing, the valve must be fully opened to allow the upper seal to function (which is generally possible under pressure). When replacing, install suitable packing in the packing box and tighten the packing gland nut. Regularly check in the future to prevent the gland nut from loosening.
When replacing valve disc parts, lift the valve stem, remove the valve cover, and then install a new valve disc on the new clamping frame. Rotate the valve stem until the valve disc is detached from the clamping frame, replace it with a new valve disc and clamping frame, and install it into the valve. The operation of replacing the valve disc is convenient.
To grind the valve disc (which can be used to grind updated valves), a small amount of grinding agent is applied to the valve disc, and then grinding is carried out. The grinding method is to place a pivot pin on the nut groove of the valve disc and the hole of the valve stem support head, place the component on the valve body, unscrew the connecting sleeve, and then grind it alternately in forward and reverse directions. Use the valve stem as a grinding tool and grind it after placing the abrasive. The grinding should not be excessive. When the grinding is completed, clean the abrasive and lubricate the threads.
The function of a check valve is to allow fluid to pass through only in one direction to prevent backflow of the medium.
The most common type of check valve on urea plants is the lift check valve, whose valve disc moves up and down along the centerline of the channel, which is reliable in action, but has high fluid resistance and is suitable for small and medium-sized applications. Lift check valves can be divided into straight through type and vertical or angle type. Straight through lift check valves can generally only be installed in horizontal pipelines, while vertical lift check valves should generally be installed in vertical pipelines where the medium flows from bottom to top, and angle lift check valves can only be installed in vertical pipelines.
Special attention should be paid when adjusting larger spring-loaded safety valves, as neither the user, manufacturer, nor maintenance workshop has sufficient ability to accurately verify the discharge pressure. Unless accurate adjustments are made at the manufacturing plant or actual installation, no adjustments shall be made to the spring-loaded safety valve.
We know that the maintenance workload required for most valves is minimal, which means that most valves do not need to be repaired frequently. Sometimes, even small issues like valve stem leakage can become major problems due to negligence. Moreover, some reckless operators fail to close valves according to technical specifications, resulting in bent valve stems or severe damage to the closing components. Such situations occur from time to time.
The threaded joint between the valve stem nut and the valve stem should be regularly lubricated with lubricating oil, which can not only reduce the friction between them, but also extend their service life. This is also a very important protective measure. If the worn valve stem nut is still in use, it may break, causing the entire axial force of the valve stem to be unsupported and the valve to lose its function.
At the beginning of the gasket, there is a simple leakage, which eventually leads to the danger of steam leakage. To avoid this danger, the valve cover bolts should be tightened appropriately at the beginning of the leak; If the sealing surface of the valve seat is not properly selected, there may be a small amount of leakage at the beginning, and later it may expand to groove leakage, and there may be insufficient opening height, which accelerates the erosion of the fluid and leads to complete damage to the valve seat.
The reason for the bending of the valve stem may be due to the operator turning the handwheel excessively after closing the valve.
There are multiple reasons for valve damage. In fact, with some training for operators, similar situations may be avoided.
Now, we will explain the use, maintenance, and repair of several common valves one by one.
Globe valve is a commonly used shut-off valve, mainly used to connect or cut off the medium in the pipeline. In the pipeline system, the time when the shut-off valve is not operated is very short, so regular maintenance is necessary.
A small amount of packing leakage can be solved by simply tightening the packing gland nut. But when the packing is damaged, it must be replaced. When replacing the packing, the valve must be fully opened to allow the upper seal to function (which is generally possible under pressure). When replacing, install suitable packing in the packing box and tighten the packing gland nut. Regularly check in the future to prevent the gland nut from loosening.
When replacing valve disc parts, lift the valve stem, remove the valve cover, and then install a new valve disc on the new clamping frame. Rotate the valve stem until the valve disc is detached from the clamping frame, replace it with a new valve disc and clamping frame, and install it into the valve. The operation of replacing the valve disc is convenient.
To grind the valve disc (which can be used to grind updated valves), a small amount of grinding agent is applied to the valve disc, and then grinding is carried out. The grinding method is to place a pivot pin on the nut groove of the valve disc and the hole of the valve stem support head, place the component on the valve body, unscrew the connecting sleeve, and then grind it alternately in forward and reverse directions. Use the valve stem as a grinding tool and grind it after placing the abrasive. The grinding should not be excessive. When the grinding is completed, clean the abrasive and lubricate the threads.
The function of a check valve is to allow fluid to pass through only in one direction to prevent backflow of the medium.
The most common type of check valve on urea plants is the lift check valve, whose valve disc moves up and down along the centerline of the channel, which is reliable in action, but has high fluid resistance and is suitable for small and medium-sized applications. Lift check valves can be divided into straight through type and vertical or angle type. Straight through lift check valves can generally only be installed in horizontal pipelines, while vertical lift check valves should generally be installed in vertical pipelines where the medium flows from bottom to top, and angle lift check valves can only be installed in vertical pipelines.
Special attention should be paid when adjusting larger spring-loaded safety valves, as neither the user, manufacturer, nor maintenance workshop has sufficient ability to accurately verify the discharge pressure. Unless accurate adjustments are made at the manufacturing plant or actual installation, no adjustments shall be made to the spring-loaded safety valve.
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