How should valves be maintained when they are parked for a long time?

Organize maintenance work: D manufacturer’s maintenance

Maintenance of the transmission parts: During the opening and closing process of the valve, the lubricant that was originally applied gradually wears away. Additionally, factors such as temperature and corrosion also cause the lubricant to dry out over time. Therefore, the moving parts of the valve should be inspected regularly, and oil should be added promptly if it is lacking, in order to prevent increased wear due to a lack of lubricant, which could lead to problems such as inflexible operation or jamming. Maintenance during valve greasing 1. When greasing valves, the issue of the amount of grease used is often overlooked. After filling the grease gun with grease, the operator selects the valve and the grease injection connection method, and then proceeds with the grease injection process. There are two scenarios: on one hand, if the amount of fat injected is insufficient, the sealing surface wears down more rapidly due to the lack of lubricant. On the other hand, excessive injection of fat leads to waste. It is because there is no accurate calculation of the sealing capacity for different valves based on their type categories. The sealing capacity can be calculated based on the valve size and type, after which an appropriate amount of lubricant should be applied. 2. When applying lubricant to valves, the pressure issue is often overlooked. During the fat injection process, the injection pressure fluctuates regularly between peaks and valleys. Too low pressure: leakage or failure of the seal. Too high pressure: blockage of the grease filling port, hardening of the grease inside the seal, or sticking of the seal ring to the valve ball and valve plate. Usually, when the grease injection pressure is too low, the injected grease flows mostly to the bottom of the valve chamber, a phenomenon that typically occurs in small gate valves. If the injection pressure is too high, on one hand, check the injection nozzle; if the grease holes are blocked, replace it accordingly ； On the other hand, there is lipid hardening; in this case, a cleaning solution must be used to repeatedly soften the degraded sealing grease, followed by the injection of new lubricating grease as a replacement. In addition, the seal type and material also affect the grease injection pressure; different types of seals result in different grease injection pressures, with hard seals generally requiring a higher pressure than soft seals. 3. When injecting grease into a valve, pay attention to the valve’s position whether it is in the open or closed state. Ball valves are generally kept in the open position during maintenance; in special cases, they are closed for maintenance. Other valves cannot all be assumed to be in the open position. During maintenance, the gate valve must be in a closed position to ensure that lubricant fills the sealing grooves along the seal rings; if it is open, the lubricant will fall directly into the flow channels or valve chamber, resulting in waste. 4. When filling the valve with lubricant, the effectiveness of this process is often overlooked. During the fat injection process, the pressure, amount of fat injected, and switch position are all normal. However, to ensure the effectiveness of grease injection into the valve, it is sometimes necessary to open or close the valve in order to check the lubrication effect and confirm that the surface of the valve ball or gate is evenly lubricated. 5. When injecting grease, pay attention to the drainage from the valve body and pressure relief through the plug. After the valve pressure test, the gas and moisture inside the sealing chamber increase in pressure due to rising ambient temperatures; therefore, it is necessary to drain the waste fluid and relieve pressure before applying grease, to ensure smooth grease application. After fat injection, the air and moisture in the sealed chamber are thoroughly displaced. Releasing the pressure in the valve chamber in a timely manner also ensures the safe use of the valve. After the fat injection is completed, be sure to tighten the drain and pressure relief plugs to prevent any accidents. Use and Maintenance 1. The purpose of use and maintenance is to extend the lifespan of the valve and ensure reliable operation. 2. The valve stem threads, which are in constant friction with the valve stem nut, should be coated with a little yellow grease, molybdenum disulfide, or graphite powder to provide lubrication. 3. For valves that are not opened and closed frequently, it is still necessary to rotate the handwheel regularly and apply lubricant to the valve stem threads to prevent sticking. 4. For outdoor valves, a protective cover should be installed on the valve stem to prevent rain, snow, dust, and rust from causing damage. 5. If the valve is of mechanical type, lubricant should be added to the gearbox on a regular basis. 6. Keep the valves clean at all times. 7. Regularly check and maintain the integrity of the valve’s components. If the fixing nut of the handwheel comes loose, it must be replaced with a proper one; makeshift solutions should not be used, as this will wear out the square portion at the upper end of the valve stem, gradually reducing the reliability of the fit until the valve can no longer be operated. 8. Do not use valves to support other heavy objects, and do not stand on valves. 9. The valve stem, especially the threaded portion, should be wiped regularly, and any lubricant that has become dirty due to dust should be replaced with fresh lubricant, as dust contains hard particles that can easily wear down the threads and the surface of the valve stem, thereby reducing its service life.

Seal the parts prone to corrosion with lubricant

Reply to 3# shglpv Thank you

Apply butter to the screw rod, and set the valve to an appropriate position.

All areas prone to corrosion should be sealed with grease

In my opinion, another factor that needs attention is the variation in temperature differences; for example, when the vehicle is parked, the temperature and pressure inside the pipes can be relatively high, or residual materials may cause corrosion of the pipe fittings. It is recommended that for long-term parking, the system should cool and lose pressure naturally after parking, and then the system should be replaced once it has returned to normal temperature. For media such as steam, which condenses after the system is stopped, it tends to accumulate in the low points. It is recommended to turn on the low-point drain to completely remove this accumulation and to keep the drain open.

If the valve is not removed, it is best to fill the system with nitrogen to maintain pressure. The outer surface is primarily treated to prevent corrosion.

This post was last edited by security on 2011-7-25 at 17:11. Hello, there is a lot of information available regarding the maintenance of valves. The friends mentioned above have provided detailed explanations, but there are still issues related to poor control during use, slow response times, damage to the valve body, or internal leaks, which require repair. This is especially true in critical processes, as problems with valves can pose significant risks.