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How should valves be maintained and maintained

Release time: 2023-02-11

Valves and other mechanical products, also need to be maintained. Maintenance work done well, can significantly extend the service life of the valve.

1. Maintenance of valves

The purpose of custody maintenance is to prevent the valve from being damaged or degraded in custody. In fact, improper storage is one of the important reasons for valve damage.

Valve storage, should be in good order, small valves on the shelf, large valves can be neatly placed on the warehouse ground, not disorderly pile, do not let the flange connection surface directly contact the ground. This is not only for aesthetic reasons, but more importantly, to protect the valve from breakage. Due to improper storage or handling, hand wheel broken, valve stem crooked, hand wheel and valve stem fixed nut loose loss, these unnecessary losses should be avoided.

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

Valve inlet and outlet should be sealed with wax paper or plastic sheet to prevent dirty things from entering the valve.

To rust in the atmosphere of the valve, should be coated with anti-rust oil, to protect, beware of rust.

Outdoor valves must be covered with rain-proof and dust-proof items such as linoleum or tarpaulin. The warehouse where the valves are stored should be kept clean and dry.

2. Valve operation and maintenance

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

Valve stem thread, often friction with the valve stem nut, need to apply yellow dry oil, molybdenum disulfide or graphite powder, lubrication.

Do not often open and close the valve, but also to regularly turn the handwheel to add lubricant to the valve stem thread, in case of biting.

Outdoor valves, to the valve stem protective sleeve, to prevent rain, snow, dust and rust. If the valve is mechanical, the transmission should be lubricated on time.

Make sure the valve is clean.

Always maintain and maintain valve component integrity. If the fixing nut of the handwheel falls off, it should be matched and not used properly, otherwise it will round the upper square of the valve stem, gradually lose the reliability of the match, and even cannot be started.

Do not use the valve to carry other heavy objects, do not stand on the valve, etc.

Valve stem, especially despise thread part, to often wipe, has been polluted by dust lubricant to replace with a new, because the dust contains shadow debris, easy to wear thread and stem surface, affect the service life of the valve.

Valves put into operation shall be maintained once a quarter, once half a year after putting into operation, once a year after two years into operation, and before winter every year. Perform valve flexibility and blowdown once a month.

3. Maintenance of packing

Packing is directly related to whether the valve switch leakage of the key seals, if the packing failure, resulting in leakage, the valve is equal to failure, especially the urea pipeline valve, because of its temperature is relatively high, so the corrosion is relatively serious, packing easy to aging. Strengthening maintenance can extend the life of packing.

When the valve leaves the factory, due to temperature and other factors, it may occur extravasation, then it is necessary to tighten the nut on both sides of the packing gland in time, as long as there is no leakage, and then the extravasation situation will be tightened again, do not tighten once, so as to avoid the loss of elasticity of the packing and the loss of sealing performance.

Some valve packing is equipped with molybdenum dioxide lubrication paste, when used for a few months, should be timely to add the corresponding lubrication grease, when it is found that the filler needs to be added, should be timely increase the corresponding packing, to ensure the sealing performance.

4. Maintenance of transmission parts

Valve in the process of switching, the original lubricating oil will continue to lose, coupled with the influence of temperature, corrosion and so on, will also make the lubricating oil continue to dry up. Therefore, the transmission parts of the valve should be checked frequently, and it is found that it should be replenished in time, to guard against increased wear due to the lack of lubricant, resulting in flexible transmission or clamping failure and other failures.

5. Maintenance of valve grease injection

The problem of the amount of grease is often ignored when valve grease is injected. After the grease gun is refueling, the operator chooses the connection mode of valve and grease injection and carries out grease injection operation. There are two situations: on the one hand, the amount of fat injection leads to insufficient fat injection, and the sealing surface is accelerated by the lack of lubricant. On the other hand, excessive fat injection causes waste. Is not according to the valve type category, the sealing capacity of different valves for accurate calculation. Can be calculated by valve size and category sealing capacity, and then reasonable injection of appropriate grease.

Valve grease is often ignored when the pressure problem. In the process of fat injection operation, the pressure of fat injection regularly shows peaks and valleys. If the pressure is too low, the seal leaks or fails, if the pressure is too high, the grease filling mouth is blocked, the grease cherry blossoms in the seal or the sealing ring is locked with the valve ball or valve plate. Usually, when the grease injection pressure is too low, more grease is injected into the bottom of the valve chamber, which generally occurs in small gate valves. And the grease injection pressure is too high, on the one hand to check the grease injection nozzle, such as the fat hole blocking situation to replace, on the other hand is the hardening of grease, to use cleaning liquid repeatedly soften the failure of the seal fat, and inject new grease replacement. In addition, sealing type and sealing material, also affect the fat injection pressure, different seal forms have different fat injection pressure, in general, hard seal fat injection pressure is higher than soft seal.

Valve grease, pay attention to valve switch position. Ball valve maintenance is generally in the open position, special circumstances choose to close maintenance. Other valves can not be treated in open position. The gate valve must be closed during maintenance to ensure that the grease is filled with sealing groove along the sealing ring. If open, seal grease directly into the flow or valve chamber, resulting in waste.

Valve grease is often ignored when the grease effect. During the grease injection operation, the pressure, the amount of grease injection and the switching position are normal. However, in order to ensure the valve grease effect, sometimes it is necessary to open or close the valve, check the lubrication effect, and confirm that the valve ball or ram surface lubrication is uniform.

During grease injection, attention should be paid to valve body blowdown and wire plugging pressure relief. After the valve pressure test, the gas and water in the valve chamber of the sealing chamber will increase the pressure because of the increase of the ambient temperature. When the grease injection is carried out, the pressure relief should be carried out first, so as to facilitate the smooth grease injection. After grease injection, the air and water in the sealing cavity are fully replaced. Timely release of valve chamber pressure, but also to ensure the safety of valve use. After the grease injection, be sure to tighten the drain and pressure relief wire plug to prevent accidents.

Grease injection should also observe the valve diameter and sealing ring seat flush problem. For example, ball valve, if there is open interference, you can adjust the open limiter to confirm the straight diameter after the sun set. Adjust the limit not only the pursuit of open or close side position, to consider the whole. If the opening position is even and not closed in place, it will cause the valve to close loosely. Similarly, adjust the close in place, but also consider the corresponding adjustment of the open position. Make sure the valve has a right Angle stroke.

After grease injection, be sure to seal the grease injection mouth. Avoid the entry of impurities or lipid oxidation at the grease injection mouth. The cover should be coated with anti-rust grease to avoid rust. For the next operation application.

Keywords: Valves