The main function of the rotary joint is to transport the medium (liquid, gas) between two pipes (equipment) with different angles, so the direct criterion for judging the quality of the rotary joint is whether it is leaking. However, there is a lot of knowledge about the leakage of rotary joints, because the causes of leakage include not only product quality problems, but improper selection, improper installation, and improper maintenance may also lead to leakage. We have talked about the selection method of rotary joints before, so I will learn about the installation and maintenance methods of rotary joints with you today.

The dry goods are here, get ready for the small bench!
- Correct installation method of rotary joint-
-01-Preparation work and precautions before installation
Before installing the rotary joint, remove all hard particles and other dirt inside the pipe, roller and rotary joint.
1) Check whether the type, specification, model, and direction of rotation of the selected rotary joint are correct, and whether the connecting parts with the machine and the pipe (pipe section) are missing.
2) When the rotating shaft of the rotary joint is connected by thread, check whether the direction of the thread is opposite to the direction of rotation of the rotating body and whether the size is the same.
3) The factory date of the rotary joint should be checked before installation. In principle, it should not be stored for more than 6 months. If it exceeds 6 months, it is best to return it to the original manufacturer and retry the pressure. For rotary joints equipped with ball bearings, if the original grease has failed due to a long period of time, the rotary joints must be disassembled before installation to remove the failed grease, clean the parts, and replace with new greases. Pay attention to different greases. Mixed use is more likely to cause failure of ball bearings.
4) The rotary joint should avoid impact and fall during the transportation and storage process, so as not to damage the interface and internal parts.
5) For the connection between the rotary joint and the pipeline, it is best to use a hose connection (a flexible metal hose is recommended), and a rigid connection is not recommended. The rotary joint should be left with a displacement elastic space.

-02-Installation order
The rotary joint should be installed correctly according to the requirements of the installation and operation manual, otherwise its sealing performance and its life will not be fully utilized.
1) Assembly and installation of one-way rotary joint and matching equipment.
Connect the metal hose and the transition joint (or flange) directly to the rotary joint. When connecting, use a bench vise to clamp the rotary joint housing to prevent damage to the seal.
When the rotating shaft and the matching rotating body are connected by thread, usually apply a layer of white lead oil or PTFE tape on the thread, and clamp the rotating shaft with a tool (usually designed with a wrench clamping plane) and align it. Screw in the center of the screw connection hole of the rotating body until it is tightened.
When the rotating shaft and the matching rotating body are connected by flange, a washer of uniform thickness should be added to the end of the rotating shaft of the extended flange (such as copper gasket, PTFE gasket), and then the end of the rotating body should be aligned. The mating part and the screw hole are fixed with bolts. When tightening the bolts, the angle should be tightened, and the torque should be equal to the final tightening.
Assemble the rotating joint's anti-rotation and load-bearing lifting structural parts, and adjust the concentricity of the shell and the hollow shaft to prevent the shell from vibrating or rotating when the rotating joint is installed and used.
2) The connection between the outer pipe and the matching rotating body of the two-way inner pipe fixed rotary joint is the same as that of the one-way rotary joint, but the difference is the installation of the inner pipe.
The connection method of the inner tube and the end cap of the rotary joint generally adopts taper pipe thread and pipe thread connection, and the connection is opposite to the rotation direction of the equipped rotating body, and the rotation direction of the outer pipe using the thread or the equipped rotating body is the same. When the outer pipe is connected by flange, after the inner pipe and the end cover are connected by threads, the end of the inner pipe must be locked in the end cover with a nut.
When installing, align the inner tube from the end hole of the outer tube inward to the screw hole of the end cap of the rotary joint, and then send the inner tube into the inner cavity of the rotating body. If the siphon type is adopted, the siphon bend should be adjusted. The head pipe mouth is downward, and then the outer pipe is fixedly assembled and connected with the matching rotating body.
3) The connection and assembly of the two-way inner tube rotary joint outer tube and the matching rotating body are the same as the one-way rotary joint, but the difference is the installation and assembly of the inner tube.
Before installing the outer tube, first assemble the inner tube with the matching rotating body. In this structure, the inner tube and the equipped rotating body are generally screwed together, and the direction of rotation is opposite to that of the equipped rotating body.
Remove the end cap of the rotary joint. When packing is used between the inner and outer pipes, remove the packing gland and the anti-rotation pin (some rotary joints are designed with this part), loosen the packing or take it out according to the situation. Packing, then align the inner tube with the center of the outer tube, and fix the outer tube with the rotating body, and then assemble the inner tube packing gland, end cap, etc. in the reverse order of the original disassembly.
4) The following work should be done before connecting with the pipe fittings equipped with fluid conveying:
Pull the rotary joint shell by hand or a tool to check whether the rotation is flexible, otherwise it is necessary to find out the reason and adjust it.
When equipped with a ball bearing and designed with lubricating grease filling and drain holes, check whether the filling hole is upward and the drain hole is downward, and check whether the straight-through grease cup is damaged or blocked during transportation.
Check and adjust whether the fluid entering or exiting the pipeline corresponds to the corresponding channel of the rotary joint and meets the design requirements.
Assemble the rotation-stop and load-bearing lifting structural parts of the rotary joint, and adjust the concentricity of the shell and the hollow shaft to be consistent.
5) Assemble and connect metal flexible hoses (or other flexible hoses) and other related pipe fittings according to the installation and operation manual of the rotary joint, and connect and fix them with the pipes that convey the fluid.