Technical knowledge

Technical knowledge

Mechanical seal installation instructions

Mechanical seal installation instructions

  • November 7,2019.

Mechanical seal installation instructions


1. Verify the seal to be installed, check whether the pump number or pump model marked on the sealing box is consistent with the machine and pump to be installed, consult the sealing assembly drawing, and master the sealing structure and installation position;

2. According to the disassembly order and requirements related to the machine and pump, remove the shaft sleeve box and other related parts of the machine and pump, and remove the old sealing device.

3. Inspect the appearance and dimensions of the relevant parts of the pump's seal chamber, including matching dimensions, space dimensions, line position tolerances, etc., and handle accordingly.

4. Detail checking

4.1 check the axial and radial run-out values of the rotating axis relative to the static cavity in the sealing chamber, to ensure that it does not exceed the limit value stipulated by relevant national standards.

Check all the shaft ends, and the runout is less than 0.1mm; Axial and radial direction inspection, runout less than 0.05mm.

Check the verticality between the end face of sealing cavity and the shaft, the tolerance is less than 0.05mm.

If the above requirements cannot match, the relevant parts shall be repaired and adjusted.

4.2 In order to avoid non-metallic auxiliary sealing ring being damaged during the installation, 2x30 degree chamfering shall be done on the shoulders of all shafts that have slipped through the sealing ring. The sharp corners shall be rounded and smoothed. Chamfering shall also be made on the inner diameter edges and corners of the outer chamber with sealing ring. Edges and corners shall be made on the key slot or the countersunk hole. The roughness Ra of the metal surface in contact with the stationary sealing ring shall be less than 3.2.

4.3 For the first installation shall check whether the connection fit size of the mounting mechanical seal conforms to the requirements of the assembly drawing, and whether there is any interference between the internal space and the external space size.

5. Clean the sealing chamber and check again whether there is any damage or defect on the surface of each part.

6. Wipe the surface of each part and apply appropriate amount of lubricant to all fitting parts. The selected lubricant should be compatible with the auxiliary sealing rubber material and sealed medium, such as water, soapy water, silicon grease, ethylene glycol or glycerin, etc. Epdm rubber material can not contact mineral oil.

For the integrated mechanical seal, the sleeve and gland are fixed, do not forget to remove the limit plate after the completion of seal assembly, or let the limit plate in the place not in contact with the rotating parts fixed.

Reference to seal assembly drawing requirements, Connect flush, quench, drain line and seal auxiliary system of the seal, the small hole in the flush joint of the gland leads to the sealing chamber, do not mixed with the quench and drain port. In addition, in order to make it convenient for users to take over the left and right ends or the front and rear ends when installing the mechanical seals of our company, two flush or quench interfaces had been symmetrically processed on the same gland. After using one of the interface, the other unused one must be sealed up. When both flush interfaces are not used, it is necessary to check whether they are both sealed up.


1. The installation steps of mechanical seals are closely related to the structure of the equipment, which should be installed in accordance with the characteristics of the equipment.

2. During the installation of each part, the force should be carefully and evenly applied. During the installation, the force should not be applied to the end face and accessories of the end face to prevent the deformation of the end face and the damage of brittle components.

3. If it is a bellows seal, do not overcompress the bellows, so as not to cause the bellows to lose elastic.

4. Do not use lubricant on the sealing end face.

5. When install plain gasket sealing ring, make sure uniform axial fastening force within the circumference.

Pre-start operation

1. Open the inlet valve of the pump, introduce the medium, and observe the sealing condition under certain static pressure.

2. Slowly turn the pump shaft by hand to observe whether the seal is leaking. If there is a big leak, the seal should had installation problems or there are some other problems with the sealing ring itself, should open the seal carefully to find the reason, and reinstall after troubleshooting.

3. If the condition is good, the pump can be started. The crystallized medium needs to be warmed to melt the crystals before starting the pump. For high temperature medium pump, slowly heating according to the requirements, start the pump after the sealing chamber reach the appropriate temperature.

4. Pay attention to the opening and closing requirements of valves in the auxiliary system pipeline, and whether the auxiliary system works well.

5. At the beginning of the pump starting, there may be microwave leakage in the mechanical seal, which is normal, and the leakage will gradually decrease. If the leakage continues to increase, it indicates that there is an installation problem or a problem with the sealing parameters. Should carefully analyze the possible problems, stop the operation when necessary, disassembled the pump to find out.

Seal disassembled

1. Before removing the machine seal, make sure that the pump has stopped running and the temperature and pressure meet the safety requirements of disassembly. Close the system pipeline valves and drain the remaining media in the pump.Toxic, harmful, flammable media need to be rinsed or diluted to meet the requirements of innocuity.

2. Remove the relevant parts on the pump. When removing the machine seal, the assembly type mechanical seal shall first insert the limit plate into the limit slot to fix, after remove the shaft sleeve and the fixing of the gland, remove the mechanical seal as a whole.

3. When disassembling the shaft sleeve parts, force on the shaft sleeve disassembling groove of the seal or on the non-seal closing surface.

4. For the parts to be reused, pay attention to protect the sealing end face and other sealing surface, do not force on the end face and its accessories.

5. For mechanical seals that do not reach normal service life, in order to analyze the cause of trouble and failure, please keep the removed seals  carefully and properly.

During the mechanical seal operation, please pay attention to the following conditions, to ensure the service life of the seal:

1. Avoid fluctuation of the medium pressure:

2. Avoid frequent starts and stops;

3. Avoid exhausting pumping, cavitation or other problem;

4. Avoid the interruption of washing fluid, and chilled water; Regularly check whether the sealing auxiliary system works properly;

5. Avoid using hard quality chilled water;

© Copyright: 2021 PUHLER (Guangdong)Smart Nano Technology Co.,Ltd. All Rights Reserved.

IPv6 network supported


Leave a message

Leave a message

    If you have questions or suggestions,please leave us a message,we will reply you as soon as we can!