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Valves, like other mechanical products, require maintenance. If this work is done well, it can extend the service life of the valve. The maintenance of the valve will be introduced below.

Valve storage and maintenance

The purpose of storage and maintenance is to prevent the valve from being damaged or to reduce the quality during storage. In fact, improper storage is one of the important causes of valve damage.

Valves should be kept in a well-organized manner. Small valves should be placed on the shelves. Large valves can be neatly arranged on the floor of the warehouse. They should not be piled up. Do not let the flange connection surface touch the ground. This is not only for the sake of beauty, but mainly to protect the valve from damage.

Unnecessary losses should be avoided due to improper storage and handling, breakage of the hand wheel, tipping of the valve stem, loosening of the fixing nut between the hand wheel and the valve stem, etc. These unnecessary losses should be avoided.

For valves that are not in use for a short period of time, the asbestos packing should be removed to avoid electrochemical corrosion and damage to the valve stem.

Valves that have just entered the warehouse should be inspected. If rain or dirt enters during transportation, wipe them clean before storing them.

Valve inlets and outlets should be sealed with wax paper or plastic sheets to prevent dirt from entering.

Anti-rust oil should be applied to the processed surface of the valve that can rust in the atmosphere to protect it.

Valves placed outdoors must be covered with rainproof and dustproof items such as linoleum or tarpaulin. The warehouse where the valves are stored must be kept clean and dry.

Valve maintenance

The purpose of use and maintenance is to extend the life of the valve and ensure reliable opening and closing.

The stem thread often rubs against the stem nut. A bit of yellow dry oil, molybdenum disulfide or graphite powder should be applied for lubrication.

For valves that do not open and close frequently, turn the handwheel regularly to add lubricant to the valve stem threads to prevent biting.

For outdoor valves, a protective sleeve should be added to the valve stem to prevent rain, snow, dust and rust.

If the valve is mechanically actuated, add lubricant to the gearbox on time.

Always keep the valve clean.

Always check and maintain the integrity of other valve components. If the fixing nut of the handwheel falls off, it must be matched and cannot be used together, otherwise it will grind the four sides of the upper part of the valve stem, and gradually lose the reliability of the cooperation, and even cannot be started.

Do not rely on the valve to support other heavy objects, and do not stand on the valve.

The valve stem, especially the threaded part, should be wiped frequently, and the lubricant that has been contaminated with dust should be replaced with new ones, because the dust contains hard debris, which is easy to wear the thread and the surface of the valve stem, which affects the service life.

Valve packing maintenance

The packing is directly related to whether the key sealing part of the leakage occurs when the valve is switched. If the packing fails, causing the leakage, the valve is equivalent to failure, especially the valve of the urea pipeline, because the temperature is relatively high, the corrosion is more harmful, and the packing is easy to age. Enhanced maintenance can extend the life of the packing.

When the valve is shipped from the factory, in order to ensure the elasticity of the packing, the pressure test under static pressure is generally subject to leak. After the valve is installed in the pipeline, extravasation may occur due to temperature and other factors. At this time, it is necessary to tighten the nuts on both sides of the packing gland in time. As long as there is no leakage, the extravasation will be tightened again in the future, not once. Tighten to prevent the filler from losing its elasticity and loss of sealing performance.

Some valve packings are filled with molybdenum disulfide grease. After several months of use, the corresponding lubricating grease should be added in time. When the packing needs to be supplemented, the corresponding packing should be added in time to ensure its sealing performance.

Valve transmission parts maintenance

In the process of opening and closing of the valve, the original lubricating grease will be continuously lost, coupled with the effects of temperature, corrosion and other factors, the lubricating oil will continue to dry up. Therefore, the transmission part of the valve should be checked frequently, and the lack of oil should be added in time to prevent increased wear due to lack of lubricant, resulting in failures such as inflexible transmission or stuck casing failure.

Valve maintenance

When the valve is filled with grease, the problem of the amount of grease injected is often ignored. After refueling the grease gun, the operator selects the connection method of the valve and the grease injection, and then performs the grease injection operation. There are two situations: on the one hand, the amount of grease injected is small, and the amount of grease injected is insufficient, and the sealing surface wears out due to the lack of lubricant. On the other hand, excessive fat injection causes waste. It is because there is no accurate calculation of the sealing capacity of different valves according to the type of valve. The sealing capacity can be calculated based on the valve size and type, and then a proper amount of grease can be injected reasonably.

When the valve is filled with grease, the pressure problem is often ignored. During the operation of fat injection, the pressure of fat injection changes regularly in peaks and valleys. 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 seal ring is locked with the valve ball and valve plate. Generally, when the injection pressure is too low, the injected grease 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, and then replace it; on the other hand, the grease is hardened. Use cleaning fluid to repeatedly soften the failed sealing grease and inject new grease for replacement . In addition, the seal type and seal material also affect the grease injection pressure. Different seal types have different grease injection pressures. In general, the hard seal grease injection pressure is higher than the soft seal.

When filling the valve with grease, pay attention to the problem of the valve in the switch position. The ball valve is generally in the open position during maintenance, and it is closed and maintained under special circumstances. Other valves can not be treated 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 directly fall into the flow channel or valve cavity, causing waste.

When the valve is filled with grease, the problem of the effect of grease injection is often ignored. The pressure, the amount of grease and the switch position are normal during the grease injection operation. 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 is evenly lubricated.

When injecting grease, pay attention to the problem of valve body drainage and wire plug pressure relief. After the pressure test of the valve, the gas and moisture in the valve cavity of the sealed cavity are increased due to the increase of the ambient temperature. When the grease is injected, the sewage must be discharged to relieve the pressure to facilitate the smooth operation of the grease injection. After grease injection, the air and moisture in the sealed cavity are fully replaced. The pressure in the valve cavity is released in time, which also ensures the safety of the valve. After grease filling, be sure to tighten the drain and pressure relief plug to prevent accidents.

When injecting fat, pay attention to the problem of even fat. During normal grease injection, the grease hole closest to the grease injection port will first grease out, then to the low point, and finally to the high point, and the grease will be successively discharged. If there is no regular or no fat, it is proved that there is a blockage, and clearing treatment should be carried out in time.

When injecting grease, also observe that the valve diameter is flush with the sealing ring seat. For example, if there is an interference in the opening position of the ball valve, the opening limiter can be adjusted inward to confirm that the diameter is straight and then locked. Adjusting the limit can not only pursue the position of one side, but consider it as a whole. If the open position is flush and the closing is not in place, it will cause the valve to not close tightly. In the same way, when the adjustment is closed, the corresponding adjustment of the opening position should also be considered. Ensure the right-angle travel of the valve.

After filling the grease, be sure to seal the grease port. To prevent impurities from entering or oxidation of lipids at the grease injection port, apply anti-rust grease to the cap to avoid rust. It will be applied in the next operation.

When injecting grease, it is also necessary to consider the specific problems in the future sequential delivery of oil products. In view of the different qualities of diesel and gasoline, the scouring and decomposition capabilities of gasoline should be considered. In the future valve operation, when encountering the gasoline section operation, add grease in time to prevent wear and tear.

When injecting grease, don't neglect the grease in the valve stem. There is a sliding bushing or packing on the valve shaft, and it needs to be kept in a lubricated state to reduce the frictional resistance during operation. If lubrication cannot be ensured, the torque increases when the electric operation wears parts, and the switch is laborious during manual operation.

When maintaining the valve, we must also pay attention to the water inflow problem in the electric head and its transmission mechanism. Especially the rainwater seeping in the rainy season. One is to rust the transmission mechanism or transmission sleeve, and the other is to freeze in winter. When the electric valve is operated, the torque is too large, and damage to the transmission components will cause the motor to be unloaded or the over-torque protection trips, and the electric operation cannot be achieved. The transmission components are damaged and manual operation is not possible. After the over-torque protection action, manual operation also cannot be switched. Forcible operation will damage the internal alloy parts.

Valve maintenance should be treated with a scientific attitude, so that the valve maintenance work can achieve its due effects and application purposes. In order to make production run normally, in terms of valves, these three points must be done:

1. The correct selection of valves is the basis.

2. The correct use of the valve is the most critical.

3. Correct maintenance is guaranteed.