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Cast Ball Valve Maintenance work seems simple, but it is not.

The professional maintenance of valves before welding, before production and after production plays a vital role in serving the valves in production operations. Correct, orderly and effective maintenance will protect the valves, make the valves function normally and extend the service life of the valves. The following aspects are often overlooked in the work: First, when greasing the valves, the problem of grease injection amount is often ignored. After the grease gun is refueled, the operator selects the valve and grease injection connection method, and then performs the grease injection operation. There are two situations: on the one hand, the amount of grease injection is small and the grease injection is insufficient, and the sealing surface accelerates wear due to lack of lubricant. On the other hand, excessive grease injection causes waste. It is because the sealing capacity of different valves is not accurately calculated according to the valve type category. The sealing capacity can be calculated according to the valve size and category, and then the appropriate amount of grease can be reasonably injected. Second, the pressure problem is often ignored when greasing the valve. During the grease injection operation, the grease injection pressure changes regularly in peaks and valleys. If the pressure is too low, the seal will leak or fail. If the pressure is too high, the grease injection port will be blocked, the grease in the seal will harden, or the seal ring will be locked with the valve ball or valve plate. Usually, when the grease injection pressure is too low, the injected grease will flow into the bottom of the valve cavity, which usually happens in small gate valves. If the grease injection pressure is too high, on the one hand, check the grease injection nozzle. If the grease hole is blocked, replace it according to the situation; 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 greasing the valve, pay attention to the problem of the valve in the switch position. Ball valves are generally in the open position during maintenance, and closed maintenance is selected in special circumstances. Other valves cannot be treated as open. Gate valves must be in the closed state during maintenance to ensure that the grease fills the sealing groove along the sealing ring. In the open position, the sealing grease falls directly into the flow channel or valve cavity, causing waste. Fourth, when greasing the valve, the greasing effect is often ignored. The pressure, greasing amount, and switch position are all normal during the greasing operation. However, in order to ensure the greasing 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 is evenly lubricated. Fifth, when greasing, pay attention to the problem of valve body drainage and screw plug pressure relief. After the valve pressure test, the gas and moisture in the sealing chamber valve cavity increase due to the increase in ambient temperature. When greasing, drain and pressure relief should be performed first to facilitate the smooth progress of greasing. After greasing, the air and moisture in the sealing cavity are fully replaced. Timely release of valve cavity pressure also ensures the safety of valve use. After greasing, be sure to tighten the drainage and pressure relief screw plugs to prevent accidents. Sixth, when greasing, pay attention to the problem of uniform grease output. During normal greasing, the grease output hole closest to the greasing port will output grease first, then to the low point, and finally to the high point, and grease will be output one by one. If it is not regular or no grease is output, it proves that there is a blockage and it should be cleared in time. Seventh, when injecting grease, you should also observe the flushness of the valve diameter and the sealing ring seat. For example, for a ball valve, if there is an interference in the opening position, you can adjust the opening limiter inward and lock it after confirming that the diameter is straight. When adjusting the limit, you should not only pursue the opening or closing position, but also consider the overall situation. If the opening position is flush and the closing position is not in place, the valve will not be closed tightly. Similarly, when adjusting the closing position, you should also consider the corresponding adjustment of the opening position. Ensure the right-angle stroke of the valve. Eighth, after injecting grease, be sure to seal the grease injection port. Avoid impurities from entering or lipid oxidation at the grease injection port, and apply anti-rust grease to the cap to avoid rust. So that it can be used for the next operation. Ninth, when injecting grease, you should also consider specific problems in the future oil product sequential transportation. In view of the different qualities of diesel and gasoline, the flushing and decomposition capabilities of gasoline should be considered. In the future valve operation, when encountering gasoline section operations, add grease in time to prevent wear. Tenth, when injecting grease, do not ignore the grease injection of the valve stem. There are sliding sleeves or packings on the valve shaft, which also need to be lubricated to reduce the friction resistance during operation. If lubrication cannot be ensured, the torque will increase during electric operation, wear parts, and it will be difficult to switch when manually operated.Eleventh, some ball valves are marked with arrows on the valve body. If there is no English FIOW handwriting, it is the direction of the sealing seat, not as a reference for the medium flow direction, and the valve self-drain direction is opposite. Under normal circumstances, the double-seat sealed ball valve has a two-way flow direction.Twelfth, when maintaining the valve, you should also pay attention to the problem of water ingress in the electric head and its transmission mechanism. Especially rainwater seeping in during the rainy season. One is to rust the transmission mechanism or transmission sleeve, and the other is freezing in winter. The torque is too large when the electric valve is operated, and the damage to the transmission components will cause the motor to be unloaded or the over-torque protection to trip and cannot realize electric operation. The transmission components are damaged, and manual operation cannot be performed. After the over-torque protection is activated, manual operation cannot be switched on and off. If forced operation is performed, the internal alloy components will be damaged. 　　In summary, valve maintenance is a science, and its results cannot be seen or touched. Only by truly treating it with a scientific attitude can valve maintenance work achieve the desired effect and application purpose.