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Cause Analysis Of Mechanical Seal Leakage
Feb 21, 2018

The common mechanical seal leakage causes the action damage, the seal surface plane degree damage, the sealing surface lubrication breakage and the multiple factor superposition function causes the leakage and so on.

(i) Action damage leakage

The moving ring and the static ring rotate frequently with the axis, not only change the sealing end face, but also increase the axial movement, especially the accumulation of the heat and pressure, and gradually reduce the precision of the mechanical seal. In the longer term, the seal face, pins, bushings, bolts and springs and other parts damage or deformation, loss of the following, resulting in sealing leakage.

1, slurry into the plug to make the spring function is limited, the movement of the sliding parts, sealing surface wear, damage the sealing. The action of mechanical seals can also be seriously affected by the filling of only trace slurry.

2, sliding sealing surface wear, hardening, aging, so that shaft and sleeve damage, spring seat wear, bending and so on.

3, adhering to the high oil-type decomposition coking or carbide particles in the solution of the precipitation fraction of the crystallization caused by micro-leakage bonding.

(ii) Damage to the surface of the seal plane leakage

The surface of the sealing plane is damaged by uneven slip marks or facial cut marks.

1, the Pump sealing box end face and agitator head deformation, damage, bolt fastening force uneven, etc. will lead to static ring seal surface deformation, causing leakage.

2. When the sliding part is hot-loaded, the temperature change and the thermal expansion difference cause the sealing surface deformation. Will make the seal due to the same piece of Confucianism change, loose, structural thermal stress is too high and thermal deformation is too large and damaged. Lead to leaks.

(iii) Lubrication damage leakage of sealing surface

End-Face seal not only by the sealing function of the end liquid film to seal the purpose, but also Shang surface liquid film lubrication function and normal operation.

1, the end of the liquid film damage will lead to dry friction, so that the sealing surface becomes rough and accelerated wear and tear, and even sic and superhard hard wear materials such as the crack.

2, sliding friction surface temperature rises sharply, can not be removed in time to remove the heat accumulation will lead to seal the surface of the seal liquid evaporation, lubrication film disappeared after the dry friction. Speed up the sealing surface damage, easy to trigger a sudden mass leakage. Therefore, it is necessary to strictly follow the procedures to check cooling conditions such as water-cooled system.

(iv) Multi-factor superposition effect leakage

The high viscosity liquid and the back and back operation of the machine is prone to "carbon scar" (the seal surface of the bulge of the Micro "bubble scar") as the starting point, the radiation growth cracks, peeling, shedding and other defects. The effect of multiple factors such as dry friction, bad sliding, flatness deformation and deformation of the opposite side rigid sliding ring can also cause leakage. These leakage phenomena are mainly caused by the local surface pressure rise and the liquid film damage, heat cycling and fatigue. Therefore, in addition to good cooling, the correct installation, ensure the mechanical seal clean and liquid film lubrication intact enhanced maintenance inspection, can eliminate hidden dangers, to ensure safe operation.