1. Main damage causes
1.1 Mechanical damage: wear
Mechanical damage also includes other forms of damage due to insufficient mechanical strength. Including wear, erosion, etc.
1.2 Heat damage: mainly overheating
It is difficult to calculate the thermal effect of mechanical seal. It can only be designed correctly from the perspective of considering the thermal effect factors, but it is necessary to know the friction coefficient, PV value, thermal conductivity, dry running performance and practical experience. Including hot crack, blister scar, etc.
1.3 Chemical damage
Surface corrosion, pitting corrosion, intergranular corrosion, stress corrosion, crevice corrosion, battery corrosion, cavitation and erosion, etc.
2. Failure analysis method of mechanical seal — visual inspection and disassembly inspection
2.1 Visual inspection of actuation characteristics of leakage medium
After the mechanical seal is installed and debugged, the static test shall be carried out to observe the leakage
If the leakage is small, it is mostly the problem of the moving ring or the static ring.
When the leakage is large, there is a problem between the friction pairs of the dynamic and static rings.
In addition, the leakage channel can also exist at the same time. Generally, there are primary and secondary differences. As long as the observation is careful and familiar with the structure, it must be able to correctly judge.
2.2 Dis-assembly inspection
When analyzing and judging the fault, we should pay attention to correctly and comprehensively reflect the fault phenomenon (make records and keep the damaged sealing elements), and take apart the sealing box in a way to judge whether it is qualified for inspection, and avoid unnecessary component damage and manpower waste caused by rush to dismantle. In fault detection, the inspection can be carried out in a sequential way: collect the whole set of sealing elements (collect all elements together for inspection and analysis), check the wear trace, check the sealing surface, check the driving (driving) parts of the seal, check the elastic elements and check the friction and collision conditions
Post time: Apr-28-2020