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| Overview of Valve Maintenance Technology |
| Article source：江阴市欧雷斯 Update Time：2025-1-18 |
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Overview of Valve Maintenance Technology
1、 Valve Overview
Jiangyin Oulei believes that valves are devices used in fluid systems to control the direction, pressure, and flow of fluids. There are various types of valves, such as gate valves, globe valves, ball valves, butterfly valves, etc., which are widely used in many industries such as power, petroleum, chemical, metallurgy, etc. Different types of valves have different structures and working principles, but they all face situations where they need to be repaired due to long-term use and malfunction.
2、 Common faults and cause analysis
Jiangyin Ouleisi summarized three common faults: valve leakage; Valve leakage; The valve cannot be opened and closed normally.
（1） Valve leakage
1. Sealing surface damage: The erosion, corrosion, and frequent friction during opening and closing of the medium may cause scratches, pits, and other damages to the sealing surface, which can damage the sealing performance and lead to internal leakage. For example, in media containing particulate impurities, particles will continuously impact the sealing surface, accelerating its wear.
1. Failure of sealing gasket: The gasket will experience aging, deformation, cracking, and other conditions when working in high temperature, high pressure, or corrosive media environments for a long time, losing its intended sealing function. Valves and gaskets in high-temperature steam pipelines are prone to aging due to high temperatures.
（2） Valve leakage
1. Packing box leakage: Packing is a key component to prevent medium leakage between the valve stem and valve cover. When the packing gland is not tightly pressed, the packing is worn, or the selected packing is not suitable for the working conditions, the medium will leak out from the packing box. For example, in some high-pressure valves, if the packing gland bolts are loose, it is easy to cause leakage.
1. Leakage at the connection between the valve body and the valve cover: Loose connecting bolts, damaged sealing gaskets, or defective sealing surfaces between the valve body and the valve cover can all cause leakage at this location. In some large valves, thermal expansion and contraction caused by temperature changes may loosen the connecting bolts.
（3） The valve cannot be opened and closed normally
1. Valve stem blockage: Excessive friction between the valve stem and the packing, or bending or deformation of the valve stem, can hinder the valve stem from moving and prevent it from driving the valve core to open and close normally. For example, when the packing is pressed too tightly, the movement of the valve stem becomes difficult.
1. Valve core detachment: Due to corrosion, fatigue fracture, and other reasons, the connection between the valve core and the valve stem separates, making it impossible for the valve to control the flow of the medium normally. In some highly corrosive media, the connection between the valve core and the valve stem is prone to corrosion.
3、 Maintenance Technology and Methods
（1） Sealing surface repair
1. Grinding repair: For shallow scratches, pits, and other defects on the sealing surface, grinding can be used for repair. Using grinding tools and abrasives, grind the sealing surface according to certain process requirements to restore a smooth and even surface, achieving a good sealing effect. For example, for metal sealing surfaces, abrasives such as silicon carbide and aluminum oxide can be used for grinding.
1. Welding repair: When the sealing surface is severely damaged and cannot be repaired by grinding, welding repair can be used. Select appropriate welding materials, weld on the sealing surface, and then process the weld layer to meet the sealing requirements. During the welding process, it is necessary to strictly control the welding process parameters to prevent welding defects from occurring.
（2） Valve packing replacement
1. Dismantling old packing: First, loosen the packing gland bolts, lift the gland upwards, and then use tools to remove the old packing from the packing box. During the extraction process, care should be taken to avoid damaging the valve stem and the inner wall of the packing box.
1. Install new packing: Select the appropriate packing according to the working pressure, temperature, and medium properties of the valve. Fill the new packing into the packing box in the correct way, and use tools to press it properly for each round of packing to ensure even distribution. Finally, install the packing gland and tighten the bolts to adjust the tightness of the gland to ensure effective sealing without obstructing the movement of the valve stem.
（3） Valve stem repair
1. Straightening treatment: If the valve stem is bent or deformed, straightening method can be used for repair. Place the valve stem on the press and straighten the bent part by applying appropriate pressure. During the straightening process, it is necessary to continuously measure the straightness of the valve stem to ensure the straightening effect.
1. Replace the valve stem: When the valve stem is severely worn or broken, a new valve stem needs to be replaced. Choose a valve stem with the same material and size as the original valve stem, and replace it according to the correct installation process. During the installation process, it is important to ensure that the connection between the valve stem and the valve core is firm and reliable, and that the clearance between the valve stem and the packing box meets the requirements.
4、 Inspection and debugging after valve maintenance
（1） Stress testing
After each valve repair, Jiangyin Oureis needs to undergo pressure testing to verify its sealing performance and pressure bearing capacity. Install the valve on the testing device, fill the valve with a certain pressure medium (such as water or air), maintain the pressure for a period of time, and check whether the valve has any leakage. The pressure value for pressure testing should be determined based on the working pressure of the valve and relevant standards.
（2） Flexibility test for opening and closing
Manually or electrically operate the valve, check if the valve opens and closes smoothly, if the valve stem moves smoothly, and if there are any blockages. At the same time, observe whether the opening indication of the valve is accurate to ensure that the valve can work normally.
（3） Debugging
According to the usage requirements of the valve, Jiangyin Oulei will debug the opening pressure, closing pressure and other parameters of the valve to meet the needs of actual working conditions. For example, for safety valves, it is necessary to adjust their opening pressure to ensure accurate opening at the specified pressure and provide safety protection. |
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