Mechanical seal installation requirements

When installing

1. Pay great attention to avoid installation deviations during installation.

(1) Tightening the gland should be done after the coupling is aligned. The bolts should be evenly supported to prevent the end face of the gland from deflecting. Check each point with a feeler gauge. The error shall not be greater than 0.05 mm.

(2) Check the matching gap (i.e. concentricity) between the gland and the outer diameter of the shaft or sleeve. It should be uniform all around. Use a feeler gauge to check that the tolerance at each point is not greater than 0.01 mm.

2. The spring compression amount must be carried out according to regulations. It is not allowed to be too large or too small. The required error is 2.00 mm. Excessive pressure will increase the end face specific pressure and accelerate end face wear. If it is too small, the specific pressure will be insufficient and the sealing effect will not be achieved.

3. After the moving ring is installed, it should spring back automatically after pressing the moving ring against the spring.

Location requirements during installation

In order to ensure stable operation, long life and low leakage performance of the mechanical seal, it is very important to install it correctly on the machine. Things you must pay attention to when installing:

1. Confirmation of parts

When installing the mechanical seal on the machine, you should compare it with the assembly drawing before installation to confirm whether the parts are fully prepared. At this time, pay attention to whether there are any abnormalities such as scratches, defects, etc. on the sealing friction pair sealing surface and sealing ring. , also pay attention to whether there are any scratches on the surface of the shaft or sleeve, flange and other parts that are in contact with the packing, sealing ring (O-ring), etc. If any abnormality is found, it must be replaced or repaired before use.

During the actual installation, do not bring more parts than needed to the site. In this way, if there are any remaining parts after the installation is completed, it means that there are missing parts during installation; if there are insufficient parts, it means that unnecessary parts are also assembled. With the parts installed, this also plays a role in self-checking during installation.

(Some people think that a good assembler does not need drawings and other marks, which is wrong. Then he is just a skilled worker and not a good maintenance man)

2. Installation location

The installation instructions vary with the type of mechanical seal and the type of machine. I won’t go into details here.

Technical requirements during installation

Mechanical seals are high-precision mechanical components, and their correct installation and operation have a great impact on their service life. Generally in accordance with the standards stipulated by the Ministry of Petroleum and Chemical Industry.

The technical requirements for the pump with mechanical seal installed and the matching part of the mechanical seal are as follows:

1. Shaft curvature: maximum not greater than 0.05 mm;

2. Rotor vibration: the vibration near the shaft sleeve at the dynamic ring sealing ring shall not be greater than 0.06 mm;

3. The axial movement of the shaft is not allowed to exceed ±0.5 mm. If a shaft sleeve is provided, the shaft sleeve is not allowed to be loose;

4. The alignment error of the coupling: for gear couplings, it is not greater than 0.08 to 0.10 mm (P2008C), and for elastic couplings, it is not greater than 0.05 to 0.06 mm; (the usual practice is that the end runout is less than 0.05, and the radial runout is less than 0.10 )

5. The concentricity tolerance of the gland (stationary ring seat) and the sealing joint to the center line of the shaft is 0.05 mm, and the verticality value of the plane in contact with the gasket to the center line is 0.03 to 0.05 mm. If it cannot be reached Requirements, the sealing cavity must be processed;

6. The end of the shaft sleeve where the dynamic ring sealing ring is installed and the end of the gland (or shell) where the static ring sealing ring is installed should be chamfered and smoothed.

1. Be careful when installing and dismantling the mechanical seal. It is strictly forbidden to use hand hammers and flat shovels to avoid damaging the sealing components. If it cannot be disassembled due to scaling, it should be cleaned before disassembly.

2. If mechanical seals are used at both ends of the pump, take care of each other during assembly and disassembly to avoid focusing on one at the expense of the other.

3. For mechanical seals that have been operated, if the gland is loose and the seal moves, the dynamic and stationary ring parts must be replaced and should not be retightened for continued use. Because the original running trajectory of the friction pair will change after loosening, the sealing performance of the contact surface will be easily destroyed.