Jinzong Machinery | Cosmetic Machinery & Chemical Machinery Manufacturers
Leakage problems of mechanical seals and maintenance measures
2025-08-04
Mechanical seal technology relies on a pair or several pairs of end faces that slide relatively vertically to the shaft. They can still maintain contact under the action of fluid pressure and other forces of the compensation mechanism. With auxiliary sealing devices, the leakage can be prevented. The mechanical seal enables the contact surface of the static ring to always be in close contact with the dynamic ring during motion. The purpose of sealing is achieved by generating an appropriate ratio of pressure between the static and dynamic rings and always maintaining a layer of fluid film between them.
The main parts of mechanical seal mainly include static ring and dynamic ring, etc.; auxiliary parts also include various types of sealing rings such as O-rings U-rings and X-rings; compensation parts include springs, push rings, etc.; transmission parts include transmission screws and transmission studs, etc.; fastening include many parts, such as push rings, spring seats, covers and set screws, etc.
So what kind of equipment is the mechanical seal mostly used on? Generally speaking, mechanical seals are mostly used on centrifugal pumps, centrifuges, compressors, and reactors. It has good sealing performance, less leakage, longer service life, lower energy consumption, and does not need to be repaired frequently. The adaptability of mechanical seals is also very good, and they can generally adapt to automated production and various harsh environments such as high temperature and high pressure, as well as the harsh requirements for sealing.
Seal leakage problem
The common mechanical seal leakage cases are as follows:
1. Leakage caused by damage to the flatness of the sealing surface
Damage to the sealing surface is mostly caused by the generation of uneven sliding marks and face cutting marks. The causes may be due to deformation or damage of pump's seal chamber and the agitator's head, or uneven tightening force of the bolts, resulting in deformation of the static ring's sealing surface, and finally occurrence of leakage phenomenon. It could also be due to the change in temperature during hot assembly and the existence of thermal expansion difference, which causes the shape of the sealing surface to change The sealing performance will also be damaged accordingly, resulting in leakage problems.
2. Leakage due to lubricity damage with sealed surface
The lubricity of the end face seal is also very important. Besides relying on the end face liquid film to play the sealing role, it also relies on lubrication to complete the normal operation. Once the end face liquid film is damaged, it will cause instantaneous wear and roughness of the friction sealing surface, and even some hard materials also produce cracks and other serious phenomena. When the temperature of the sliding friction surface suddenly rises, if the heat accumulation can not be immediately removed, it will lead to the evaporation the sealing liquid and the disappearance of the lubricating film, which will lead to the occurrence of friction. Friction is very easy to damage the sealing surface and bury a large number leakage hazards.
3. Leakage caused by damage from actionability
The dynamic ring and static ring of the mechanical seal device rotate with the shaft all the time, and they always repeat the same motion frequently, which not only changes sealing end face but also increases the axial movement amount of the device, gradually reducing the accuracy of the mechanical seal. Over time, the various parts of the device will be damaged even deformed, and then they will lose their followability, resulting in leakage of the seal.
What conditions will affect the action of mechanical seal? Firstly, the accumulation of slurry will cause the spring to be blocked, the sliding parts to be out of, and the surface of the sealing surface to be worn, which seriously affects the action of the mechanical seal; When the sliding sealing surface appears wear, hardening and aging, etc, the shaft and shaft sleeve will be damaged accordingly, and the spring seat will also be worn or even bent.
4. Leakage caused by a combination of various factors
The occurrence of leakage is sometimes caused by a combination of several factors, such as friction, poor sliding, deformation of the sliding ring, and deformation of theness, which can easily lead to leakage. These causes are often due to excessive fatigue, uneven pressure, and film rupture. Therefore, correct installation and maintaining the cleanliness the mechanical seal are very important, and good cooling can better eliminate potential safety hazards.
Disclosure of repair measures
1. Countermeasures against motion disorders
Firstly, O-rings with good wear resistance and rubber elasticity are used, which can maintain their inherent shape and size even when slightly damaged, continue to maintain the sealing effect. Generally, O-rings used for sealing are mostly made of rubber or polytetrafluoroethylene. Polytetrafluoroethylene plays a corrosive role, and can be used as bellows pads or V-shaped pipes, etc. If under high temperature or low temperature conditions, generally choose stainless steel other materials of bellows as sealing rings, if it is required to be a rotating mechanical seal, the sealing ring should be used O-rings for sliding seals.
We can consider the use of long-life stationary mechanical seals, with the static ring mounted on one side of the shaft and the moving ring mounted on the side, so that the device is not affected by mechanical deformation, and at the same time, it also has a good maintenance of the flatness structure. At the same time, spring in this installation method does not come into contact with the sealing liquid, and the operability is greatly improved, which provides great convenience for the processes such as cleaning slurry and the flatness of the seal and the accuracy of the machine.
The influence of heat on mechanical seals is also very large, as heat can cause material distortion and part deformation, leading to changes in load capacity, which greatly the working performance of the seal and the likelihood of it being burned out. The treatment method needs to be determined according to the amount of heat, such as natural cooling, internal circulation, external flushing cooling, and internal circulation cooling, and the temperature of the seal should be controlled to achieve the best sealing effect.
2. Countermeasures against sliding surface
During equipment maintenance and overhaul, carefully inspect whether there is wear and sliding marks on the equipment to ensure the accuracy of the static ring surface. At the same time the use of stationary mechanical seal can well solve the wear problem. Another way to solve the sealing thermal deformation caused by the change of material stress of sliding parts is to change the mode of the O-ring or graphite ring of the sealing ring from sliding form to plug-in type.
3. Measures to prevent dry slipping
If the wear is caused by damage to the sliding surface due to insufficient cooling when sliding and heating, we can choose to configure more perfect sealing fluid and cooling and temperature control unit, and also need to carry out patrol inspection of the supply pipeline to prevent blockage. When choosing mechanical seal, it is better to use static mechanical seal better pulp resistance, so as to better prevent the occurrence of dry friction. In addition, strengthening the operation management of rotating machinery, checking the pressure and other parameters and status of mechanical on time, and solving related problems in time, is very important for maintaining the integrity and normal operation of machinery.
Closing remarks
To sum up, the leakage problem of chemical machinery seal is a very important issue, which is directly related to the safety of the entire chemical production. Once leakage occurs, it is likely to cause a major accident. Therefore, we need to focus on exploring the problem of mechanical seal and come up with better maintenance and prevention policies.
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