Mechanical seal precautionsMechanical seal

Mechanical Seal Precautions




2020-01-14 09:24






Precautions during installation



a. Pay great attention to avoid installation deviation during installation
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1) Tightening the gland should be carried out after the coupling is aligned, and the bolts should be supported evenly to prevent the end face of the gland from deflecting. Check each point with a feeler gauge, and the error is not greater than 0.05 mm.


2) Check the fit clearance (that is, concentricity) between the gland and the outer diameter of the shaft or sleeve, and make sure it is even around, and use a feeler gauge to check that the tolerance of each point is not greater than 0.01mm.


b. The amount of spring compression should be carried out according to the regulations, and the phenomenon of too large or too small is not allowed, and the error is required to be 2.00mm. Excessive pressure will increase the specific pressure of the end face and accelerate the wear of the end face. Too small will result in insufficient specific pressure and can not play a sealing role.


c. After the moving ring is installed, it should spring back automatically after pressing the moving ring to the spring.


Location requirements for installation



In order to ensure the stable operation, long life and low leakage performance of the mechanical seal, it is very important to install it correctly on the machine. Things to pay attention to when installing:



1. Confirmation of parts



When installing the mechanical seal on the machine, compare it with the general assembly drawing before installation to confirm whether the parts are ready. At this time, pay attention to whether there are any abnormalities such as scratches and defects on the sealing surface of the sealing friction pair and the sealing ring. , Also pay attention to whether there are any scratches on the shaft or sleeve surface, flange and other parts that are in contact with the packing, sealing ring (O ring), etc. If any abnormal phenomenon is found, it must be replaced or repaired before use.



During the actual installation, do not bring more parts than required to the site. In this way, if there are any remaining parts after the installation, it means that there is a missing part during installation; if there are insufficient parts, it means that unnecessary parts are also assembled. When the parts are installed, this also plays a role in self-test during installation.





2. Installation location



The installation essentials vary with the type of mechanical seal and the type of machine. I won't go into details here.



Technical requirements for installation



Mechanical seals are high-precision mechanical components, and their correct installation and operation have a great impact on their service life. We generally follow the standards stipulated by the Ministry of Petroleum and Chemical Industry.



The technical requirements of the pump and the mechanical seal with the mechanical seal installed are as follows:



1. Shaft bending: the maximum is not more than 0.05 mm;



2. Rotor vibration: no more than 0.06 mm near the shaft sleeve at the seal ring of the moving ring;



3. The axial movement of the shaft is not allowed to exceed±0.5 mm, if there is a shaft sleeve, the shaft sleeve is not allowed to be loose;



4. Alignment error of the coupling: not more than 0.08-0.10 mm for the gear coupling (P2008C), not more than 0.05-0.06 mm for the elastic coupling;<0.05, radial jump<0.10)



5. The concentricity tolerance between the gland (static ring seat) and the seal fitting spigot to the center line of the shaft is 0.05 mm, and the verticality value of the plane in contact with the gasket to the center line is 0.03 to 0.05 mm. If it cannot reach Requirements, the sealing cavity should be processed;



6. The end of the shaft sleeve where the dynamic ring seal ring is installed, and the end of the gland (or housing) where the static ring seal ring is installed should be chamfered and smooth.



7. Be careful when installing and disassembling the mechanical seal. It is strictly forbidden to use hand hammers and flat shovels to avoid damage to the sealing components. If the scale cannot be disassembled, it should be cleaned before disassembly.



8. If mechanical seals are used at both ends of the pump, they should take care of each other during assembly and disassembly, so as to prevent one from neglecting the other.



9. For the mechanical seal that has been in operation, if the gland is loose and the seal moves, the dynamic and static ring parts must be replaced, and it should not be re-tightened to continue to use. Because the original running track of the friction pair will change after loosening, the sealing of the contact surface will be easily damaged.



Precautions when disassembling


a. Be careful when installing and disassembling the mechanical seal. It is strictly forbidden to use hand hammers and flat shovels to avoid damage to the sealing components. If the scale cannot be disassembled, it should be cleaned before disassembly.


b. If mechanical seals are used at both ends of the pump, they should take care of each other during assembly and disassembly to prevent one from losing the other.


c. For mechanical seals that have been in operation, if the gland is loose and the seal moves, the dynamic and static ring parts must be replaced and should not be re-tightened to continue to use. Because the original running track of the friction pair will change after loosening, the sealing of the contact surface will be easily damaged.