Analysis and repair methods for leakage points in container mechanical seals?

Analysis and repair methods for leakage points in container mechanical seals?

There are five main leakage points:

(1) Sealing between shaft sleeve and shaft;

(2) Sealing between the moving ring and the shaft sleeve;

(3) Sealing between dynamic and static rings;

(4) Sealing static ring and static ring seat;

(5) The seal between the sealing end cap and the pump casing.

1. Analysis and identification of leakage factors

1. Leakage during static testing of equipment. After adjusting the mechanical seal device, it is often necessary to conduct static tests on the mechanical seal to investigate the leakage rate. If the leakage is small, it is common to see doubts about the sealing of the dynamic ring Sulzer pump matching machine or the static ring sealing ring; When there is a large amount of leakage, it indicates that there is a contradiction between the dynamic and static rings. On the premise of investigating the leakage amount and identifying the leakage location, conduct a manual turning investigation. If there is no significant change in the leakage rate, there is an objection to the sealing rings of the static and dynamic rings; If there is a significant change in leakage during turning, it can be determined that there is a problem with the customized machine seal pair due to the contradiction between the dynamic and static rings; If the leaked material sprays radially, there are mostly doubts about the dynamic ring seal. If the leaked substance sprays or leaks from the water cooling hole to the surrounding area, the static ring sealing ring is often ineffective. In addition, leakage channels can also exist together, but generally there are differences in order. Only through detailed research and understanding of the structure can it be correctly identified.

2. Leakage during trial operation. According to static tests, the centrifugal force generated during high-speed operation of pump mechanical seals will reduce medium leakage. Therefore, during the trial operation, the root cause of seal leakage after ineffective cleaning of the shaft and end cap seal is the secondary damage caused by the contradiction between the dynamic and static rings. The main factors that lead to ineffective sealing of contradictory secondary seals are:

(1) During operation, due to abnormal phenomena such as convulsions, cavitation, and pressure build-up, the axial force is large, causing the separation of the contact surface between the dynamic and static rings;

(2) Excessive tightening during equipment sealing resulted in severe damage and abrasion of conflicting secondary ports;

(3) The sealing ring of the moving ring is too tight, and the tension spring cannot adjust the radial floating of the moving ring;

(4) The sealing ring of the static ring is too loose, and when the dynamic ring floats radially, the static ring gets rid of the static ring seat;

(5) The working medium contains particulate matter, which enters the sealing end faces of the contradictory pair, dynamic and static rings during work;

(6) Design selection error, slightly low sealing face pressure or significant cold shrinkage of sealing materials. The above scenery often appears during trial operation, and sometimes can be removed by adjusting the static ring seat appropriately, but most must be dismantled from scratch to replace the seal.

3. Sudden leakage during normal operation. The sudden leakage of a few centrifugal pumps during operation is caused by normal wear and tear or reaching the end of their service life, mainly due to significant changes in operating conditions or improper operation and maintenance.

(1) Evacuation, cavitation, or prolonged pressure buildup can cause seal damage;

(2) The actual output of the pump is small, and many substances are circulated by the pump, resulting in heat accumulation and evaporation of substances, leading to ineffective sealing;

(3) A slightly larger reflux rate causes sediment to accumulate at the bottom of the suction tube side vessels (tower, kettle, tank, pool), damaging the seal;

(4) Long term parking, no manual turning from scratch, conflicting with tearing of protruding surfaces due to adhesion;

(5) The increase of corrosive, polymeric, and adhesive substances in the medium;

(6) Rapid changes in working temperature;

(7) The working conditions are constantly changing or changing;

(8) Power outage or shutdown issues. If a centrifugal pump suddenly leaks during normal operation and cannot be detected quickly, it usually becomes a major accident or loss, and effective measures must be taken to pay attention to it.