Analyze the cause of seal failure of construction machinery seals

Analyze the cause of seal failure of construction machinery seals

1. During the static test of the installation, after the installation of the leaking engineering mechanical seal is debugged, a static test is usually carried out to investigate the amount of leakage. If the leakage amount is small, it is mostly because of the dynamic ring or static ring sealing ring; On the basis of starting to investigate the amount of leakage and judging the location of leakage, manually crank the investigation. If there is no obvious change in the leakage amount, the static and dynamic ring seals are in doubt; if there is a significant change in the leakage amount during cranking, it can be concluded that the dynamic There are doubts about the collision of the static ring; if the leaking medium erupts along the axial direction, the moving ring seal is mostly in doubt, and the leaking medium erupts nearby or leaks from the water cooling hole, and the static ring seal is mostly invalid. In addition, leakage channels can also exist together, but there are usually primary and secondary differences. As long as you investigate in detail and understand the layout, you will be able to judge correctly. 2. Leaks appear during trial work. After the mechanical seal of the pump has passed the static test, the centrifugal force generated by the high-speed rotation during operation will inhibit the leakage of the medium. Therefore, during the trial operation, the leakage of the mechanical seal is basically caused by the damage of the dynamic and static ring conflict pairs after the cleaning between the shafts and the failure of the end cover seal. The main factors that cause the failure of the conflicting pair of seals are: during operation, due to abnormal phenomena such as slack, cavitation, pressure holding, etc., resulting in a large axial force, the contact surfaces of the dynamic and static rings are separated; the amount of tightening when the mechanical seal is installed If it is too large, the end face of the conflict pair will be severely worn and scratched; if the sealing ring of the moving ring is too tight, the tension spring cannot adjust the axial floating amount of the moving ring; if the sealing ring of the static ring is too loose, when the moving ring floats axially, the static The ring is separated from the static ring seat; there are granular substances in the working medium, and the conflicting pair is entered during the operation, and the sealing end faces of the dynamic and static rings are flawed; . The above phenomenon often occurs in the mechanical seal factory in the trial operation, and sometimes can be eliminated by properly adjusting the static ring seat, etc., but most of them need to be disassembled and replaced from scratch. The failure caused by the loss of the lubricating film on the two sealing end faces: due to the existence of the sealing load on the end face, the pump is started when the liquid is lacking in the sealing chamber, and the dry conflict occurs; ; If the medium is a volatile commodity, when the mechanical seal cooling system is fouled or blocked, the saturated vapor pressure of the medium will rise due to the end face conflict and the heat generated by the mixing liquid of the rotating element, and the medium pressure will also be lower than its full vapor pressure. Case.