- During the operation of the machine, the mechanical seal suddenly leaked, the medium was gasoline, and the temperature reached 200 degrees Celsius. During the disassembly and inspection of the seal, it was found that the end face of the seal was excessively worn, and the seal was a single-end bellows mechanical seal.
- The following situations were found:
1. The moving ring is separated from the moving ring seat, and the moving ring is broken;
2. The seal is severely worn both dynamically and statically;
3. There are obvious narrow wear marks on the end face of the broken moving ring;
- Cause analysis of seal failure:
1. The moving ring and the moving ring seat are hot-fitted, and the linear expansion coefficients of the selected substrates are different. Under the condition of high temperature, it may be improperly fitted with interference, resulting in the separation of the moving ring and the moving ring seat;
2. There are obvious wear scars on the end face of the moving ring and the color of the wear scars is darker, indicating that there is excessive heat generation, dry friction on the sealing end face and thermal deformation of the sealing end face. If the seal compression is too large, it will aggravate the wear of the sealing end face , the particulate matter enters the sealing end face, resulting in serious wear of the sealing end face;
3. Due to the harsh operating environment of the seal, the large thermal stress leads to radial thermal cracks on the end face of the moving ring. When the pump is started and stopped, the change of the axial force of the pump and the vibration of the pump body cause the moving ring to break completely.
Actions to take in case of failure:
1. Add sealed cooling water to improve the sealed operating environment, and the cooling water is demineralized;
2. Properly adjust the amount of sealing compression, it should not be too large;
3. Before replacing the seal, check the sealing parts to avoid the problem of the quality of the sealing parts;
In the reforming device, almost every dismantling and inspection can find the wear of the sealing end face, there is cavitation phenomenon, the cooling inlet and outlet of the cooling chamber of the sealing chamber are blocked, and the seal flushing liquid cooler is blocked;
Reason analysis: The pump medium is hot water higher than 100 degrees Celsius, and the cooling medium of the seal flushing cooler is circulating water, which is easy to scale, which makes the water chamber of the sealed cavity block, and the self-flushing cooler has poor scaling and circulation, causing the inside of the sealed cavity The medium is vaporized, and the seal end face is cavitated due to dry wear of the end face, etc., which makes the seal fail;
1. Replace: heat exchangers with larger thermal area to avoid leakage of seals due to insufficient heat exchange;
2. It is recommended to change the circulating water for cooling to softened water to seal the sealing leakage caused by the blockage of the cooling system structure.