There are many reasons for the rotary joints, and the common ones are periodic leakage and small-scale submersible sewage pump seal leakage caused by the grinding shaft of rotary joints. The causes and solutions for these two leaks are different, so today Daweiruisi, the manufacturer of rotary joints, will put together an analysis for you.

First of all, let's get to know the rotary joint.

Rotary joint basic information

The rotary joint is a product specially used for low-speed and high-pressure multi-media multi-channel equipment, serving processing center turntables, hydraulic workstations, coilers, converters, large packaging turntables, and hydraulic machinery, multi-channel high-pressure controllers, and other equipment.

For a more detailed introduction to rotary joints, you can check the following article:

Types and overview of rotary joints

Periodic leakage of rotary joint:

(1) The axial blow-by of the pump rotor is large, the interference between the auxiliary seal and the shaft is large, and the movable ring of the rotary joint cannot move flexibly on the shaft. When the pump is reversed and the dynamic and static rings are worn, the displacement cannot be compensated.

Countermeasures: When assembling the mechanical seal, the axial blow-by of the shaft of the rotary joint should be less than 0.1mm, and the interference between the auxiliary seal and the shaft should be moderate, so as to ensure the radial seal of the rotary joint and ensure that the moving ring can be free on the shaft after assembly. Move (push the moving ring onto the spring)

(2) When the amount of lubricating oil on the sealing surface of the rotary joint is insufficient, the dry friction and the sealing end surface are stretched.

Countermeasures: The height of the lubricating oil surface in the oil chamber should be higher than the sealing surface of the dynamic and static rings of the rotary joint.

(3) The rotor vibrates periodically. Due to the misalignment of the stator and the upper and lower end covers, or the imbalance of the impeller and the main shaft, cavitation and bearing damage (wear), the life of the rotary joint seal is shortened, and leakage occurs.

Countermeasure: The above problems of rotary joints can be corrected according to maintenance standards.

Rotary joint seal leaks

(1) The poor sealing of the rotary joint pump below 715kW often causes the grinding shaft. The main positions of the grinding shaft are the position of the auxiliary sealing ring of the moving ring, the position of the static ring, and a few springs that have the phenomenon of grinding the shaft.

(2) The main reason for grinding the shaft

The mechanical seal on both ends of the BIA type is in a poor operating state of reverse pressure, and the particles and foreign objects in the medium are easy to enter the sealing surface of the rotary joint, and the sealing is invalid.

The main component of the shaft is the rubber bellows, and the sealing surface of the upper end of the rotary joint is in a state of poor lubrication, so the friction torque between the action rings is greater than the transmission torque between the rubber bellows and the shaft, and the relative rotation is performed.

The dynamic and static ring auxiliary seal of the rotary joint is corroded by the weak acid and weak alkali in the sewage, and the rubber component loses its elasticity. Some rotted, and some lost their proper function, resulting in the phenomenon of shaft grinding.

(3) In order to solve the above problems of rotary joints, the following measures are currently being taken:

Ensure the cleanliness of the lower end cover and oil chamber of the rotary joint, and do not assemble dirty lubricating oil.

The oil surface pipeline in the oil chamber of the machine seal should be higher than the sealing surface of the movable ring.

The above is the introduction of the grinding shaft phenomenon caused by the periodicity of the rotary joint and the leakage of the seal of the small submersible sewage pump.

I hope it will be helpful to you. For more information on rotary joints, you can click below to view:

What are the problems of rotary joints and how to deal with them?