Introduction of electric actuator for valve in power station

Introduction of electric actuator for valve in power station

Valves and other mechanical products, but also need maintenance. Good maintenance work can extend the service life of the valve.
Valves and other mechanical products, but also need maintenance. Good maintenance work can extend the service life of the valve.
1. Maintenance of valve
The purpose of storage and maintenance is to prevent the valve from being damaged or reduced in quality during storage. 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, do not let the flange connection surface directly contact the ground. This is not only for aesthetics, but more importantly to protect the valve from being damaged. Due to improper storage or handling, the handwheel is broken, the valve stem is tilted, the fixed nut of the handwheel and the valve stem is loose and lost, etc., these unnecessary losses should be avoided.
For the valve that is not used temporarily in the short term, asbestos packing should be removed to avoid electrochemical corrosion and damage to the stem.
The valve inlet and outlet should be sealed with wax paper or plastic sheet to prevent the entry of dirty things affecting the valve.
The valve can rust in the atmosphere, should be coated with anti-rust oil, to protect, beware of rust.
Outdoor valves must be covered with waterproof and dust-proof items such as linoleum or tarp. The warehouse where the valve is stored shall be kept clean and dry.
How should the valve be maintained
2. Valve use and maintenance
The purpose of use and maintenance is to extend the service life of the valve and ensure reliable opening and closing.
Stem threads, often friction with stem nut, need to be coated with yellow dry oil, molybdenum disulfide or graphite powder for lubrication.
Do not often open and close the valve, but also to regularly turn the hand wheel, add lubricant to the stem thread, to prevent biting.
For outdoor valves, protective sleeves should be added to the valve stem to prevent rain, snow, dust and rust. If the valve is mechanical, be on time to the gearbox love lubricating oil.
Keep valve clean.
Always adhere to and maintain valve component integrity. If the fixed nut of the handwheel falls off, it should be matched and can not be used properly, otherwise it will grind the upper square of the valve stem, gradually lose the reliability and even can not start.
Do not use the valve to carry other heavy loads, do not stand on the valve, etc
Stem, especially despise the thread part, often wipe, the lubricant has been contaminated by dust to replace the new, because dust contains shadow debris, easy to wear thread and stem surface, affect the service life of the valve.
The valve in operation should be maintained once every quarter, once half a year after it is put into operation, once a year after it is put into operation, and the valve should be maintained before winter every year. Perform flexible valve operation and blowdown once a month.
3. Maintenance of packing
Packing is directly related to whether leakage occurs when the valve is on and off the key sealing parts, if the packing fails, resulting in leakage, the valve is equal to failure, especially the valve of urea pipeline, because its temperature is relatively high, so the corrosion is relatively serious, the packing is easy to aging. Strengthening maintenance can prolong the life of packing.
When the valve leaves the factory, due to temperature and other factors, there may be extravasation, then it is necessary to tighten the nut on both sides of the packing gland in time, as long as it does not leak, and then tighten again in the case of extravasation, do not tighten once, so as not to lose the flexibility of the packing and the loss of sealing performance.
Some valve packing with molybdenum dioxide lubrication paste, when used for a few months, should be added to the corresponding lubricating grease in time, when it is found that the packing needs to be supplemented, should be added to the corresponding packing in time to ensure the sealing performance.
4. Transmission parts maintenance
Valve in the process of switching, the original lubricating oil will continue to lose, coupled with temperature, corrosion and other effects, will also make the lubricating oil constantly dry up. Therefore, the transmission part of the valve should be regularly checked, found that it should be timely filling, beware of increased wear due to lack of lubricant, resulting in inflexible transmission or jam failure and other faults.
5. Maintenance of valve grease injection
When the valve is greased, the problem of how much grease is often ignored. After the valve is greased, the operator chooses the connection mode of the valve and grease to carry out the grease operation. There are two situations: on the one hand, less fat injection leads to insufficient fat injection, and the sealing surface accelerates wear due to the lack of lubricant. On the other hand, excessive fat injection, resulting in waste. There is no accurate calculation of different valve sealing capacities based on valve type and category. The sealing capacity can be calculated by valve size and type, and then reasonable injection of appropriate grease.
Pressure problems are often ignored in valve grease injection. In the process of fat injection, the pressure of fat injection has a regular peak and valley change. If the pressure is too low, the seal leakage or failure, if the pressure is too high, the grease injection port is blocked, and the grease cherry or sealing ring in the seal is locked with the valve ball and valve plate. Usually, when the grease injection pressure is too low, the injected grease flows into the bottom of the valve chamber, which generally occurs in small gate valves. If the grease injection pressure is too high, on the one hand, check the grease injection nozzle and replace it if the blockage of the fat hole is identified. On the other hand, the grease is hardened. Cleaning liquid should be used to soften the failed sealing grease repeatedly and inject new grease to replace it. In addition, sealing type and sealing material also affect the grease injection pressure, different sealing forms have different grease injection pressure, in general, the hard seal grease injection pressure is higher than the soft seal.
When greasing the valve, pay attention to the problem of valve switch position. Ball valve maintenance is generally in an open state, special circumstances choose to close maintenance. Other valves should not be open. Gate valve in maintenance must be in the closed state, ensure that grease along the seal ring full of sealing groove. If open, sealing grease directly into the flow or valve cavity, resulting in waste.
The effect of valve grease injection is often ignored. The pressure, the amount of fat and the switch position are all normal in the operation of fat injection. However, in order to ensure the valve grease effect, sometimes it is necessary to open or close the valve, check the lubrication effect, confirm the valve ball or gate surface lubrication is uniform.
When grease injection, attention should be paid to the valve body sewage and silk blockage pressure relief problems. After the valve pressure test, the gas and water in the sealed chamber valve chamber will increase pressure because of the increase of ambient temperature, and the sewage discharge pressure relief should be carried out first to facilitate the smooth operation of the grease injection. After grease injection, air and moisture in the sealed cavity are fully displaced. Timely discharge valve chamber pressure, but also to ensure the safety of the use of the valve. After grease injection, the drain and pressure relief wire must be tightened to prevent the occurrence of accidents.
Grease injection should also observe the valve diameter and sealing ring seat flush problem. For example, ball valve, if there is interference, you can adjust the opening limiter inward, confirm that the diameter is straight after the sun. Adjust the limit can not only pursue on or off position, to consider the whole. If the opening position is even and the closing is not in place, the valve will be closed loosely. Similarly, adjust the switch in place, also consider the corresponding adjustment of the open position. Ensure right Angle stroke of valve.
After grease injection, be sure to seal the number of grease injection mouth. Avoid impurities into, or grease mouth grease oxidation, cover to smear anti-rust grease, to avoid rust. For the next operation.
Power station valve electric actuator is introduced position indicating device (3) check, the electric actuators are installed on the test bench, the valve position indicator agency pointer to “seated” position, no-load start electric actuators, check the pointer with the output shaft rotation, when the reach regulation in several “open” position (such as valve), The rotation process and position of the pointer shall comply with the provisions of 5.2. 10, and the number of tests shall not be less than three times. The enclosure protection performance test shall be carried out in accordance with GB 4208 and the results shall be in accordance with 6.1.2.