Forged steel valves often ignore the problem of grease injection. After the grease injection gun is refueled, the operator selects the valve and the grease injection connection method, and then performs the grease injection operation. The forged steel gate valve has two situations: on the one hand, the amount of grease injection is small and the grease injection is insufficient, and the sealing surface wears quickly due to the lack of lubricant. On the other hand, excessive grease injection results in waste. The reason is that there is no precise calculation of the sealing capacity of different valves according to the valve type. The sealing capacity can be calculated according to the valve size and type, and then a reasonable amount of grease can be injected.
For the forged steel gate valves pressure problems are often ignored. During the grease injection operation, the grease injection pressure changes regularly with peaks and valleys. The pressure is too low, the seal leaks or the safety valve fails, the pressure is too high, the grease injection port is blocked, the sealing lipids are hardened, 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 injection nozzle. If the grease hole is blocked, replace it after identifying the situation; On the other hand, it is the hardening of grease. It is necessary to use cleaning fluid to soften the failed sealing grease repeatedly and inject new grease to replace it. In addition, the sealing type and sealing material also affect the grease injection pressure. Different sealing forms have different grease injection pressures. Generally, the grease injection pressure of hard seals is higher than that of soft seals.
For the forged steel globe valve, pay attention to the position of the valve switch. The ball valve is generally in the open position during maintenance, and in special cases, it is selected to be closed for maintenance. Other valves cannot all be maintained in the open position. The forged steel globe valve must be closed during maintenance to ensure that the grease fills the sealing groove along the sealing ring. If it is opened, the sealing grease will fall directly into the flow channel or valve cavity, causing waste. When the valve is greased, the effect of grease injection is often ignored. During the grease injection operation, the pressure, grease injection volume, 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, check the lubrication effect, and confirm that the surface of the valve ball or gate plate is evenly lubricated.
For the forged steel check valves, pay attention to the valve body blowdown and wire plug pressure relief problems. After the valve pressing test, the gas and moisture in the valve cavity of the sealing cavity are boosted due to the increase of the ambient temperature. When injecting grease, it is necessary to discharge the sewage and release the pressure first, so as to facilitate the smooth progress of the grease injection. The air and moisture in the sealing cavity are fully replaced after grease injection. The valve cavity pressure is released in time, which also ensures the safety of the valve. After the grease injection, be sure to tighten the drain and pressure relief plugs to prevent accidents. When injecting grease, pay attention to the problem of uniform grease. During normal grease injection, the grease discharge hole closest to the grease injection port will discharge grease first, then to the low point, and finally to the high point, and the grease will be discharged one by one. If it does not follow the rules or there is no grease discharge, it proves that there is a blockage, and it should be cleaned in time.
For the forged steel extended end gate valves, also observe that the valve diameter is flush with the sealing ring seat. For example, a ball valve, if there is interference in the opening position, you can adjust the opening position limiter inward, and then lock it after confirming that the diameter is straight. Adjusting the limiter should not only pursue the position of opening or closing, but should be considered as a whole. 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 closed position, the corresponding adjustment of the open position should also be considered to ensure the right-angle stroke of the valve. After grease injection, be sure to seal the grease injection port. To avoid the entry of impurities, or the oxidation of lipids at the grease injection port, the cover should be coated with anti-rust grease to avoid rusting, so that it can be used in the next operation.
The sealing surface of the high-pressure forged steel gate valve is a plane or a conical surface, and the opening and closing part is plug-shaped disc, which move linearly along the center line of the fluid. The movement form of the valve stem includes a lifting rod type (the valve stem rises and falls, and the handwheel does not rise and fall), and there is also a lifting rotary rod type (the handwheel rotates and lifts together with the valve stem, and the nut is located on the valve body).
For the forged steel cryogenic valves, it is necessary to consider specific problems in the sequential transportation of oil products in the future. Given the different qualities of diesel and gasoline, the scour and disintegration ability of gasoline should be considered. In the future operation of the valve, when encountering the gasoline section operation, grease should be added in time to prevent wear.
When injecting grease, do not neglect the grease injection at the valve stem. There are sliding bushings or packings on the valve shaft, which also needs to be kept in a lubricated state to reduce the frictional resistance during operation. If lubrication cannot be ensured, the torque will increase to wear parts when operated electrically, and the switch will be laborious when operated manually.
Some ball valves are marked with arrows. If there is no FIOW in English, it is the direction of action of the sealing seat, not as a reference for the flow direction of the medium, and the direction of the valve self-draining is opposite. Typically, double seated ball valves have bidirectional flow.