HOW TO EXTEND THE SERVICE LIFE OF MECHANICAL SEALS

When it comes to gland packings, we will definitely think about mechanical seals. The mechanical seal is an oil seal device of a rotating machine, that is, a device that solves the seal between the rotating shaft and the body. The mechanical seal is also called an end face seal. With the continuous development of science and technology, more and more high requirements are put forward for the technical level of mechanical seals. The service life of mechanical seals is one of the important signs to measure the level of mechanical seals.

The mechanical seal is generally composed of a moving ring, a static ring, an elastic pressing element, and an auxiliary sealing element. The service life of the mechanical seal is related to its material selection, installation and daily maintenance.

1. Material Selection of Mechanical Seals

The technical level and service life of mechanical seals are closely related to the reasonable selection of materials. Different environments should use different materials. When selecting materials, it is necessary to consider not only the consistency of the selected materials, but also environmental differences, such as the concentration, temperature, pressure and corrosion of the medium. Usually, we can choose spring seals, elastomer bellow seals, pump seals, etc.

2. Installation of Mechanical Seals

The mechanical seal is a precision component. If it cannot be installed correctly, it will seriously affect its mechanical seal performance and shorten its service life. Therefore, pay attention to the following requirements during the installation of the mechanical seal.

1) The spring compression must be carried out in accordance with the regulations, not too large or too small, the error is +2 mm.

2) When installing the moving ring, ensure that the moving ring moves flexibly on the rotating shaft.

3) When the shaft or shaft sleeve of the mechanical seal is installed, when the shaft diameter is 10 ~ 50mm, the radial circle runout deviation is ≤0.04mm. When the shaft diameter is 50 ~ 120mm, the radial circle runout deviation is ≤0.06mm.

4) The surface roughness of the shaft or sleeve where the mechanical seal is installed is ≤3.2 μm.

5) The gland should have a medium circulation flushing hole, and the tail of the static ring should have a cooling flushing hole.

6) The sleeve cannot move axially.

7) Before installation, confirm that the product model, specifications and requirements are consistent, and clean the parts to ensure the smoothness of the pipeline.

8) After installation, dynamic and static pressure tests should be carried out separately, and it can be put into use after passing the test.

4. Use and Maintenance of Mechanical Seals

1) Establish a sealing liquid and cooling system, and check and replace it frequently to strengthen the cooling of the end face.

2) During maintenance, special tools should be used. It is forbidden to strike the seals to avoid corrosion caused by local phase change.

The mechanical seal is an important part of the equipment and it is the weakest link. Once it leaks, it must be shut down and replaced. Only by strict selection of materials, correct installation and correct use and maintenance, a good mechanical seal effect can be achieved, and the service life of the mechanical seal can be extended to meet production needs.