Resolving Typical Plug Valve Malfunctions

 
Plug valves serve as crucial fluid control devices widely utilized in various pipeline systems within industrial production. However, due to prolonged usage or transportation, plug valves may encounter diverse malfunctions that impede their normal operations. This article aims to introduce common issues associated with plug valves and corresponding diagnostic and treatment methods, facilitating engineers in better maintaining and managing these equipment.

1. Difficulty in Operating the Valve
 
When experiencing difficulties in operating plug valves, it's often due to a severe lack of sealing grease on the plug surface, resulting in inadequate lubrication. In such cases, promptly adding sealing grease and repeatedly toggling the valve is necessary to lubricate the plug surface sufficiently. Through gradual operation, the valve's aperture will gradually increase, ultimately returning to normal status. To ensure long-term stability, it's essential to continue adding sealing grease after operation has normalized to guarantee adequate lubrication on the plug surface.
 
2. Minor Leakage at Bottom Valve Cover
 
During transportation, particularly under severe vibrations, the plug may impact the valve cover, causing surrounding fastening screws to loosen and resulting in slight external leakage at the bottom valve cover. Addressing this issue involves tightening the screws to restore the valve's sealing performance. It's worth noting that this situation is more prevalent in valves with larger diameters.
 
3. Internal Leakage of the Valve
 
Internal leakage of the valve typically arises from insufficient sealing grease on the plug surface. In such instances, adding an ample amount of sealing grease to ensure its thorough distribution on the plug surface is necessary to achieve effective sealing. In rare cases, after pressurization until stabilization, the plug may require a period of self-adjustment to ensure its sealing performance. If internal leakage persists despite sufficient sealing grease, inspecting the central adjusting screw at the bottom and tightening it to restore performance is recommended.
 
4. Slight External Leakage at Valve Stem or Above
 
Slight external leakage at the valve stem or above is often caused by insufficient packing. In such scenarios, promptly adding packing material to compensate for the deficiency is necessary. When adding packing material, inserting small sections into the packing gland and slowly tightening the packing screw to push the material inward is crucial to ensure proper sealing. If packing material cannot be further added, rotating the valve to redistribute the packing material more effectively can facilitate complete sealing.
 
In conclusion, various diagnostic and treatment methods exist for addressing the different malfunctions of plug valves. Timely identification of issues and implementation of effective measures are crucial in ensuring the long-term stable operation of plug valves. It is hoped that this information will assist engineers in better managing and maintaining plug valves, thereby ensuring the smooth operation of production systems.