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Preface to the Lubrication Procedures for Valve Maintenance: Valve maintenance is a very important task that must be carried out thoroughly before and after the valve is used. Because the maintenance of valves is related to their performance and reliability. This will also be related to the entire piping system. Valves should be stored in a dry and well-ventilated area, with both ends of the passage blocked. Valves that are stored for long periods should be inspected regularly, cleaned of dirt, and coated with rust preventive oil on their working surfaces. After installation, regular inspections should be carried out. This article provides a brief overview of the precautions for valve maintenance, intended solely as a reference for servicing purposes. Main inspection items for grease injection during valve maintenance: 1. Wear condition of the valve’s sealing surfaces. 2. Wear condition of the trapezoidal threads on the valve stem and valve stem nut. 3. Check whether the filler is outdated or ineffective; if damaged, it should be replaced promptly. 4. After the valve has been overhauled and assembled, a sealing performance test should be conducted. Maintenance tasks during valve greasing: 1. Professional maintenance of valves before welding, before commissioning, and after commissioning plays a crucial role in ensuring that these valves can function properly in production operations. Proper, orderly, and effective maintenance helps to protect the valves, enables them to perform their functions as intended, and extends their service life. Valve maintenance may seem simple, but it is not. There are often overlooked aspects in work. 2. When greasing valves, the issue of the amount of grease applied 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 can be applied. 3. When greasing valves, the pressure issue is often overlooked. During the fat injection process, the injection pressure fluctuates regularly between peaks and valleys. Too low pressure: seal leakage or failure. Too high pressure: blockage at the grease filling port, hardening of the grease inside the seal, or sticking of the seal ring to the valve ball or 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. 4. If the grease injection pressure is too high, first check the grease 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 sealant, followed by the injection of new lubricant to replace it. Furthermore, the sealing method and the sealing material also affect the grease injection pressure; different sealing types result in different grease injection pressures, with hard seals generally requiring a higher pressure than soft seals.