What are the ways to maintain the valve


The purpose of maintenance is to extend the life of the […]

The purpose of maintenance is to extend the life of the Ball Valve and ensure reliable opening and closing. The thread of the valve stem often rubs against the nut of the valve stem. It is necessary to apply a little yellow dry oil, molybdenum disulfide or graphite powder for lubrication. Valves that do not open and close frequently , It is also necessary to turn the handwheel regularly to add lubricant to the valve stem thread to prevent it from being bitten. For outdoor valves, a protective sleeve should be added to the valve stem to prevent rain, snow, dust, rust and dirt. If the valve is mechanically waiting, Add lubricant to the gearbox on time. Always keep the valve clean. Always check and maintain the integrity of the other parts of the valve. If the fixing nut of the handwheel falls off, it must be equipped and cannot be used properly, otherwise it will grind the upper part of the valve stem, gradually lose the reliability of cooperation, and even fail to operate. Do not rely on the valve to support other heavy objects, and do not stand the valve on the valve The rod, especially the threaded part, should be wiped frequently, and the lubricant that has been soiled by dust should be replaced with a new one. Because the dust contains hard debris, it is easy to wear the thread and the surface of the valve stem, and affect the service life.


The filler is directly related to the valve. Whether the key seals leak when switching occurs, if the packing fails, causing leakage, the valve will also fail, especially the valve of the urea pipeline, because the temperature is relatively high, corrosion is more harmful, and the packing is prone to aging. Strengthening maintenance can extend the life of the packing. When the valve leaves the factory, in order to ensure the elasticity of the packing, it is generally subject to static pressure test without leakage. After the valve is installed in the pipeline, extravasation may occur due to factors such as temperature. At this time, the nuts on both sides of the packing gland should be tightened in time, as long as there is no leakage, and no extravasation will occur in the future. Tighten it to prevent the packing from losing elasticity and loss of sealing performance. Some valve packing is equipped with molybdenum disulfide grease. After several months of use, the corresponding lubricating grease should be added in time. When it is found that the packing needs to be supplemented, it should be increased in time. Packing to ensure its sealing performance. When the valve is greased, the problem of grease injection is often ignored. After the grease gun is refueled, the operator selects the valve and the grease injection connection mode, 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 wears faster due to lack of lubricant. On the other hand, excessive grease 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 valve size and type, and then a reasonable amount of grease can be injected. The pressure problem is often ignored when the valve is greased. During the fat injection operation, the fat injection pressure changes regularly. If the pressure is too low, the seal leaks or fails, the pressure is too high, the grease injection port is blocked, the grease in the seal is 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; on the other hand, if the grease is hardened, use a cleaning fluid to repeatedly soften the failed sealing grease and inject new grease to replace it. . In addition, the seal type and sealing material also affect the grease injection pressure. Different sealing forms have different grease injection pressures. Generally, the grease injection pressure for hard seals is higher than that for soft seals.


When injecting grease on valves, pay attention to the problem of valve in the switch position . The ball valve is generally in the open position during maintenance. In special cases, it is selected to close for maintenance. Other valves cannot be treated as open positions. 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 directly fall into the flow path or valve cavity, causing waste. When the valve is greased, the grease injection effect is often ignored problem. During the grease injection operation, the pressure, grease injection volume and switch position are all normal. However, in order to ensure the effect of valve grease injection, it is sometimes necessary to open or close the valve to check the lubrication effect to confirm that the valve ball or gate surface is evenly lubricated. When grease injection, pay attention to the problem of valve body drainage and plug pressure relief. After the valve pressure test, the gas and moisture in the valve cavity of the sealed cavity will increase in pressure due to the increase of ambient temperature. When grease injection, the pressure must be discharged first to facilitate the smooth progress of grease injection. After grease injection, the air and moisture in the sealed cavity are fully replaced. Relieve the valve cavity pressure in time, which also guarantees the safety of the valve. After the grease injection, be sure to tighten the drain and pressure relief plug to prevent accidents.