Mechanical Seal Repair Solutions

With the requirements of production safety and environmental protection, the application of mechanical seals is more and more extensive. At present, most of the rotating equipment of enterprises use mechanical seals to protect the leakage between the dynamic and static sealing surfaces, but the mechanical seal is a relatively precise part of the equipment.

Parts, in the process of operation and maintenance, the requirements for technicians are relatively high. Here are some problems of mechanical seal repair.

1. Installation of mechanical seal

A large part of the reason why the mechanical seal works well or not and the length of its life is due to the working environment of the mechanical seal given by the equipment itself. Therefore, it is necessary to carefully check the equipment before installing the mechanical seal, which will reduce the possibility of mechanical seal failure and improve the mechanical seal

The service life of the equipment needs to be checked in the following aspects:

(1) The diameter and depth of the sealing cavity should be the same as those on the installation drawing of the sealing assembly, and the general tolerance should be within ±0.13mm; the dimensional deviation between the shaft and the shaft sleeve should be within ±0.0.3-±0.05. The axial movement needs to be checked, and the total movement cannot exceed 0.25mm in theory;

Radial runout is generally less than 0.05mm. Excessive radial runout may cause wear between the seal sleeve and the shaft; the self-checking leakage of the sealing surface increases, thereby affecting the overall working environment of the seal and reducing the service life of the seal

(2) Check the curvature of the shaft, the maximum curvature should be less than 0.07mm.

(3) Check the alignment between the seal cavity hole and the shaft, and the misalignment should be less than 0.13mm. Misalignment between the seal cavity hole and the shaft will affect the dynamic load between the seal faces, thereby reducing the seal operating life.

2, Check the seal before installation

Whether it is a new mechanical seal or a repaired mechanical if, it is necessary to carefully check the following: check all parts, the parts should be clean and free of dirt, especially the sealing surface; check the rotating parts, the transmission pin and the spring pin master move freely ;Check the set screw of the rotating part.

3. Start-up operation and use of mechanical seal

The correct use is very important to the service life of the mechanical seal. Generally, the following precautions are used with most mechanical seals.

(1) Most mechanical seals are designed to work in a liquid environment, so the sealing surface must be immersed in liquid before starting the machine. Dry running may damage the sealing surface and affect the service life. Jogging equipment has little effect, but at full speed it is necessary to ensure that the sealing equipment is in the working fluid.

(2) When opening the cooling or flushing system, no matter whether the equipment is running or not, it is best not to cut off the cooling or flushing system, especially when the heat medium transported by the equipment will crystallize after cooling.

(3) It is normal for the newly installed equipment to have a slight leakage at the first operation. With the running-in of the seal, the leakage will be reduced to no leakage.