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Causes and treatment of mechanical seal leakage

wallpapers Education 2020-05-21
Mechanical seal is an indispensable part of power machinery and fluid machinery devices, and it has important significance for the safety of machinery. There are various reasons for mechanical seal leakage, such as the problem of sealing flushing water, the defects of the device itself, the corrosion of the filling medium to the device, and the insufficient sealing performance. For these problems, we must start from the root cause and solve the process, equipment, and maintenance in order. 3. Operational issues, only complete troubleshooting can solve the mechanical sealing problem completely, and ensure the excellent operation of the automatic sealing.
 the reason
1. Metal corrosion: The metal itself cannot resist corrosion. Direct contact with the surface of the corrosive medium will be corroded. At the initial stage, phenomena such as strange noise, leakage, and wear will occur. Corrosion will spread inside at a specific rate. Under the action of external force, the metal will undergo stress and deformation, and the exposed part is the severely corroded area after the distortion, and gradually affects other regions through the weak links, and then produces mechanical seal leakage.
2. Non-metallic corrosion: The corrosion of the friction pair is also one of the essential reasons for the mechanical seal. The excessively high-end surface temperature, improper selection of graphite impregnating resin, and insufficient depth of graphite impregnating resin are all causes of corrosion of the friction pair. When the graphite friction pair is in an oxidizing medium when the end face is poorly cooled, or friction occurs, the environment produces three or four Baidu will cause the graphite and the oxidizing medium to oxidize, causing the end face to lose performance.
3. Corrosion of auxiliary sealing ring and contact parts: different materials have different corrosion resistance, the content of extra sealing ring is generally selected to have elastic rubber, and the corrosion of rubber will make the surface become abnormally rough and lose the original elasticity. And the high-temperature resistance of rubber is relatively weak, generally no more than two Baidu.
Failure performance
1. A leak during the static pressure test
When the mechanical seal device is installed, due to operational errors, the seal end surface will be bruised and deformed and damaged; the cleaning is not thorough enough so that the mechanical seal is trapped with particulate impurities, or it is due to the loosening of the positioning screw, the gland is not compressed, and The precision of the machine equipment is not high enough so that the sealing surfaces are not entirely fitted, it will cause the mechanical seal to fail and the medium to leak. If the leakage occurs in the shaft sleeve, the reason may be that the compression amount of the shaft sleeve sealing ring is insufficient or not compressed, or the device may have been damaged.
2. Periodic leakage
The periodic rotation of the rotor assembly and the excessive axial movement of the mechanical seal components will cause leakage of the mechanical seal. The sealing surface of the mechanical seal must be subjected to particular stress to play a right sealing role. To achieve the above requirements, the spring device of the mechanical seal must have a certain amount of compression to give certain stress to the end face, so that the mechanical seal can achieve the expected sealing effect. At the same time, to ensure that the importance is in the appropriate range, the pump shaft cannot have a large amount of movement. Still, unreasonable factors often appear in the actual design, moving the pump shaft higher than expected, which has a great degree of performance on the mechanical seal Negative Effects.
3. The mechanical seal often leaks
 The frequent leakage failures caused by the auxiliary seal ring include end face wear and loose ring. Spring-induced leaks include rotor vibration, loose parts, media problems, and damage to the assistant settings of the mechanical seal.
4. Leakage of other mechanical seals
 
Measures
1. Install anti-failure equipment
The occurrence of the fault has a special relationship with the actual operation and the internal structure of the machine. Some incentives will cause the weakness to occur under certain conditions. As long as the appropriate incentives are found, the fault incentives can be eliminated by some anti-failure equipment. For example, an electrical contact pressure gauge is installed at the pump outlet, and the pump and the pressure gauge at the outlet of the shoe are interlocked. If the pump is under pressure, it will automatically power off and stop.
2. Improve equipment structure
Mechanical seals have an unreasonable structural design, and these illogical structures increase the risk of mechanical seal leakage. When conditions permit, the structure of the mechanical seal can be redesigned to minimize the risk of leakage. For example, most of the end faces of mechanical seals are designed with single end faces. From a safety perspective, the individual end face design can be changed to a second end face design.
3. Choose the right material
Different materials have different corrosion resistance. The corrosiveness of the media requires that the mechanical seal material has excellent corrosion resistance. If the content is not selected correctly, there will be risks.
4. Improve professional skills of operators
The failure of the mechanical seal is affected by human factors in addition to the machine itself. For example, the lack of expert knowledge of the operator results in improper operation and dangerous consequences. 
5. Improve the maintenance effect
Regular maintenance is an essential means to discover problems and prevent problems. However, many employees treat it as a general routine and think that it is a walk through the field, and it is just doing what it does during maintenance. The employee's work attitude prevented some problems from being discovered early, and it was too late to wait until the issue broke out completely. Employees should pay attention to every detail when overhauling, and do not ignore any details. The company can take some incentive measures to encourage the enthusiasm of employees to repair, thereby improving the effectiveness of overhaul.
If the mechanical seal of the pump and pump frequently leaks during production, the fault must be solved in a targeted manner, the equipment should be improved based on analysis of the cause of the defect, and the material should be installed with fault prevention. Regular maintenance management should be carried out to minimize the probability of failure.
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