Valve Grease Injection Maintenance

Professional maintenance of valves before welding, production and after production plays a vital role in serving the valve in production operations. Correct, orderly and effective maintenance will protect the valve, enable the valve to function normally and extend the service life of the valve. life. Valve maintenance work seems simple, but it is not. There are often overlooked aspects of work.
First, when filling valves with grease, the amount of grease is often overlooked. After refueling the grease gun, the operator selects the valve and grease injection connection method before performing the grease injection operation. There are two situations: on the one hand, the amount of grease injected is small and insufficient, and the sealing surface wears faster due to lack of lubricant. On the other hand, excessive fat injection causes waste. The reason is that there is no accurate calculation of the sealing capacity of different valves according to the valve type category. The sealing capacity can be calculated based on the size and type of the valve, and then the appropriate amount of grease can be injected reasonably.
Second, when valves are greased, pressure issues are often ignored. During the grease injection operation, the grease injection pressure changes regularly between peaks and valleys. The pressure is too low, the seal leaks or fails, the pressure is too high, the grease injection port is clogged, the grease inside the seal hardens, or the sealing ring is locked with the valve ball and valve plate. Usually when the grease injection pressure is too low, the injected grease mostly flows into the bottom of the valve cavity, which usually occurs in small gate valves. If the grease injection pressure is too high, on the one hand, check the grease nozzle and replace it if the grease pores are blocked; on the other hand, if the grease is hardened, use cleaning fluid to repeatedly soften the failed sealing grease and inject new grease to replace it. . In addition, the seal model and seal material also affect the grease injection pressure. Different seal forms have different grease injection pressures. Generally, the grease injection pressure of hard seals is higher than that of soft seals.
Third, when injecting grease into the valve, pay attention to the problem of the valve in the switch position. Ball valves are generally kept in the open position during maintenance, and may be closed for maintenance under special circumstances. Other valves cannot be regarded as open. The gate valve must be closed during maintenance to ensure that the grease fills the sealing groove along the sealing ring. If it is open, the sealing grease will fall directly into the flow channel or valve cavity, causing waste.
Fourth, when the valve is greased, the effect of grease is often ignored. During the grease injection operation, the pressure, grease injection amount, and switch position are all normal. However, in order to ensure the grease injection effect of the valve, it is sometimes necessary to open or close the valve to check the lubrication effect and confirm that the surface of the valve ball or gate plate is evenly lubricated.
Fifth, when injecting grease, pay attention to the valve body drainage and plug pressure relief issues. After the valve pressure test, the gas and moisture in the sealed cavity valve cavity will increase in pressure due to the increase in ambient temperature. During grease injection, the sewage and pressure must be discharged first to facilitate the smooth progress of the grease injection work. After grease injection, the air and moisture in the sealed cavity are fully replaced. Timely release of valve cavity pressure also ensures the safety of the valve. After greasing, be sure to tighten the drain and pressure relief plugs to prevent accidents.
Sixth, when injecting fat, pay attention to the issue of uniform fat dispensing. During normal grease injection, the fat outlet hole closest to the grease injection port will be greased out first, then to the lowest point, and finally to the high point, and the grease will be output one by one. If it does not follow the rules or does not produce fat, it proves that there is a blockage and needs to be cleared in time.
Seventh, when injecting grease, you should also observe that the valve diameter is flush with the sealing ring seat. For example, in a ball valve, if there is opening interference, the opening limiter can be adjusted inward and locked after confirming that the diameter is straight. When adjusting the limit, don't just pursue the open or closed position, but consider the overall position. If the opening position is flush and the closing position is not in place, the valve will not close tightly. In the same way, when adjusting the closing position, the corresponding adjustment of the opening position should also be considered. Ensure right angle travel of the valve.
Eighth, after grease injection, the grease injection port must be sealed. To avoid the entry of impurities or the oxidation of the lipid at the grease injection port, the cover should be coated with anti-rust grease to avoid rust. So that it can be applied in the next operation.
Ninth, when injecting grease, we must also consider specific issues in the future sequential transportation of oil products and deal with them in detail. Given the different qualities of diesel and gasoline, the scour and decomposition capabilities of gasoline should be considered. In the future valve operation, when encountering gasoline section operations, replenish grease in time to prevent wear and tear.
Tenth, when injecting grease, do not ignore the grease injection of the valve stem. There is a sliding sleeve or packing on the valve shaft, which also needs to be kept lubricated to reduce frictional resistance during operation. If lubrication cannot be ensured, the torque will increase during electric operation and the worn parts will require laborious switching during manual operation.
11. Some ball valve bodies are marked with arrows. If there is no English FIOW wording, it is the direction of the sealing seat and is not used as a reference for the flow direction of the medium. The self-discharging direction of the valve is opposite. Typically, double-seat sealed ball valves have bidirectional flow.
12. When maintaining the valve, you should also pay attention to the problem of water intrusion in the electric head and its transmission mechanism. Especially the rainwater that seeps in during the rainy season. One is that the transmission mechanism or transmission sleeve will rust, and the other is freezing in winter. As a result, the torque is too large when the electric valve is operated. Damage to the transmission components will cause the motor to be unloaded or the over-torque protection will trip, making it impossible to realize electric operation. The transmission parts are damaged and manual operation is impossible. After the over-torque protection action, manual operation is also unable to switch. Forcible operation will damage the internal alloy components.