China Sealcon Company

Common Faults and Maintenance Methods of Pump Mechanical Seal

1. Frequent leakage during operation


(1) Leakage caused by deformation of the contact surface of the stationary ring. When the end surface pressure is too large, the heat of friction can easily cause thermal deformation of the dynamic and static rings. Of course, during the installation of spare parts, if there is uneven force, it will cause deformation of the end surface. Treatment method: Open the mechanical seal to check whether the static and dynamic ring end surface is overheated and deformed. If yes, you need to replace it. If it is caused by assembly, it can be re-assembled according to the specification.
(2) Internal impurities such as crystal particles are introduced into the friction pair. Treatment methods: Open and clean. Check the end face for wear and repair according to the specific conditions.
(3) As the auxiliary seal is improperly selected, it causes the work medium to swell and lose its elasticity. Approach: Replace the new seal and select the matching mechanical seal.
(4) The dynamic and static ring seal faces the axis with no verticality error. Treatment method: Check the shaft of the pump shaft, repair or replace it beyond the standard.
(5) The formation of scale by the static and dynamic rings and the circle kit cannot compensate the wear displacement in time. Treatment method: clean scale.
(6) Long-term operation leads to serious wear and tear on the face of the static and dynamic rings. Treatment: Replace the mechanical seal.
In short, the leakage phenomenon caused by the above reasons should be carefully checked and analyzed when the equipment is overhauled, and the symptoms should be handled.

2. The mechanical seal produces a sudden leak


The abrupt failure of mechanical seals is generally caused by the following reasons. For example, the pump appears strong vibration, vacuum and other reasons undermine the working status of the friction pair, the compensation spring breaks, anti-reverse pin off or the drive pin breaks, the auxiliary device is faulty so that the static and dynamic ring sudden changes in heat and cooling caused the sealing surface deformation or produce crack. When the above failures occur, the mechanical seal must be renewed and used again. At the same time, the problems in the operation process should be identified to facilitate the prevention work.

3. Leaking when the pump is stopped for a period of time before starting


When the medium near the friction pair is solidified, crystallized, fouled, spring rusted, and broken, any leakage can occur when the pump starts to run. To completely stop the occurrence of such phenomena, all inspections and preparations must be made before starting the pump.


4. Leaking when adding water or static pressure test


Since the mechanical seal is not installed according to the specification, leakage occurs when the water is added or the static pressure test is performed. There are several manifestations of non-standard installation:
(1) The contact surfaces of the moving and stationary rings are uneven, and bumps or damages occur during installation, resulting in seal failure;
(2) The size of the dynamic and static ring seal is wrong, damaged or not pressed;
(3) Foreign objects on the surface of moving and stationary rings, such as rust or sand dust;
(4) The seal ring on the static and dynamic ring is forcibly loaded when installed or installed, resulting in damage;
(5) The dynamic ring tightening member is not installed in place, causing the spring seat to retreat;
(6) When the pump shaft is moved by hand, if the leakage has obvious directionality, it may be due to the uneven spring force or the verticality of the seal cavity and shaft. Leakage caused by the above reasons should be dealt with according to the causes.