Installation Position of Mechanical Seal

In order to ensure the stable operation, long life and low leakage performance of the mechanical seal, it is very important to install it correctly on the machine. Matters that must be paid attention to during installation:

(1) Confirmation of parts

When installing the mechanical seal on the machine, it is necessary to compare it with the general assembly drawing before installation to confirm whether the parts are ready. At this time, pay attention to whether the sealing surface of the seal friction pair, the sealing ring, etc. have scratches, defects and other abnormal phenomena. Also pay attention to whether there are scratches on the shaft or sleeve surface, flange and other parts that contact the packing, sealing ring (O-ring), etc. If any abnormal phenomenon 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 parts left after the installation, it means that there are places that are missing during the installation; if there are insufficient parts, it means that unnecessary places are also assembled with parts, which also plays the role of self-inspection during installation (some people think that a good assembler does not need drawings and other markings, which is wrong. Then he is just a skilled worker, not a good maintenance worker).

(2) Installation location

The installation instructions vary with the type of mechanical seal and the type of machine, so we will not go into details here.

1. Technical requirements for installation

Mechanical seals are high-precision mechanical parts. Their correct installation and operation have a great impact on their service life. We generally follow the standards set by the Ministry of Petrochemical Industry.

The technical requirements for the pump and mechanical seal matching parts for installing mechanical seals are as follows:

1. Shaft bending: maximum not more than 0.05 mm;

2. Rotor runout: not more than 0.06 mm near the sleeve at the dynamic ring seal;

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

4. Coupling alignment error: for gear couplings, not more than 0.08-0.10 mm (P2008C); for elastic couplings, not more than 0.05-0.06 mm; (customary practice: end jump <0.05, radial jump <0.10) < span="">；

5. The concentricity tolerance of the gland (stationary ring seat) and the seal joint to the shaft centerline is 0.05 mm, and the verticality tolerance of the plane in contact with the gasket to the centerline is 0.03-0.05 mm. If the requirements are not met, the sealing cavity needs to be processed;

6. The end of the sleeve where the dynamic ring seal is installed and the end of the gland (or housing) where the stationary ring seal is installed should be chamfered and smoothed.

2. Causes of failure

Mechanical seal failures are generally known to people only after abnormal leakage, abnormal wear, abnormal torque and other phenomena occur. The causes of the failure are roughly the following four aspects:

1. The design and selection of the mechanical seal are incorrect;

2. The quality of the mechanical seal is poor;

3. The accuracy of the machine itself that uses or installs the mechanical seal does not meet the requirements;

4. The machine is operated incorrectly.

Specific analysis for specific situations