Correct installation and use of mechanical seal

Posted by yy on December 18th, 2020

The correct installation and use of mechanical seals are the key to ensuring long-term stability, safety and reliability. Improper installation and use will result in poor sealing performance, shortened service life or seal failure. The following briefly introduces the installation and use precautions for reference:

Check

Whether the dimensional accuracy, geometric accuracy and mutual relationship of the relevant parts of the mechanical seal meet the requirements.

1. The dimensional tolerance, surface roughness and chamfer transition shape of the shaft and static ring seat matched with the mechanical seal are shown in the following figure;

2. The radial runout of the shaft should be ≤0.04mm, and the axial runout should be ≤0.3mm;

3. The verticality of the sealing cavity and the gland combined with the positioning end facing the shaft centerline is ≤0.04mm;

4. Check whether the axial and radial dimensions of the seal cavity and gland assembly are correct.

Installation

1. The assembly size must be guaranteed as required;

2. During the entire installation process, keep the parts of the mechanical seal and the sealing cavity of the equipment clean, and it is strictly prohibited to knock or knock, so as to avoid deformation and damage of the mechanical seal friction pair and seal failure;

3. The sealing part can be coated with a layer of clean lubricant for smooth installation. Soapy water or silicone is recommended for ethylene-propylene rubber;

4. When installing the static ring gland, the tightening bolts must be evenly stressed to ensure that the end face of the static ring is perpendicular to the center line of the end cover, and note that the anti-rotation groove on the back of the static ring should be aligned with the anti-rotation pin, but not conflicting;

5. When installing seals related to the direction of rotation (such as parallel spring transmission and hook spring transmission), pay attention to whether the spring rotation direction is correct, and the spring should be tightened as it turns;

6. Install the rotating ring part. When relying on the retaining ring or impeller or spring seat to fix the shaft, ensure the working length of the rotating ring part. After installation, compress the rotating ring by hand to make the rotating ring move flexibly in the axial direction. Can recover position

7. After installation, turn the shaft by hand to check whether there is a sense of weight. If so, check whether the installation is correct.

Usage

1. Before normal driving, a static pressure test is required to check the sealing effect of the end face of the mechanical seal, the seal ring and the seal end. If there is any problem, check and solve it one by one.

2. Before normal use, perform normal pressure and normal temperature operation and run-in for a period of time to make the end faces more evenly fit, and then perform normal operating conditions;

3. During work, the sealed cavity should be filled with liquid or sealed medium to keep the end surface lubricated to avoid evacuation and dry friction.

4. When the temperature of the conveying medium is too high, too low, easy to crystallize or contains impurities, particles, flammable, explosive, or toxic, it must be flushed, cooled and filtered in accordance with the piping system in the JB/T6629 or API610 standard , Blocking and other measures to ensure the normal operation of the mechanical seal.