Industrial Rotary Joints Installation and Precautions
What is a Rotary Joint?
A rotary joint is used to transfer media such as steam, water, oil, or air from a stationary pipe to a rotating component.
Preparation Before Installation of Rotary Joint
Before installing rotary joint, it is necessary to have personnel with professional knowledge of fitter and industrial machinery, who have been trained and have relevant operating experience of pressure components.
Newly installed rollers, pipes and other flow channels often contain weld beads, weld slag, iron filings and other debris. If these debris enter the sealing surface of the rotary joint, it will cause sealing failure, jamming and other problems. Therefore, prior to installing a new rotary joint, it is highly recommended to flush the rollers and piping at a high flow rate using a suitable medium (e.g., water, compressed air, steam, or oil).
An appropriate filter must be incorporated into the piping system. This filter should be installed upstream of the flexible tube connected to the rotary joint's inlet, and it must be capable of filtering out particles ranging in size from 40 to 60 microns.
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Key Points When Installing Rotary Joint
There are three primary methods for connecting a rotary joint to a roller: threaded connections, quick-change flanges, and fixed flanges. Prior to installation, ensure that necessary supplies—such as teflon tape, gaskets, and sealing rings—are prepared in advance. Thoroughly clean the spigot and sealing faces to remove any impurities or foreign objects—such as metal shavings or burrs—that could compromise the seal or disrupt smooth operation.
When installing the rotary joint, handle it with care to avoid impacts, dropping, or rough handling, thereby preventing damage to the sealing components.
When using threaded connections, the threads of the rotary joint's rotating shaft and the fixed inner tube must be either left-handed or right-handed and kept consistent. During installation, attention should be paid to the direction of thread rotation and the direction of roller rotation. When observing the roller's thread direction from the perspective of the rotary joint installation: clockwise rotation corresponds to a left-hand thread, while counter-clockwise rotation corresponds to a right-hand thread.
When connecting the rotary joint to a flange, pay close attention to the bolt tightening sequence. For rotary joints featuring O-ring seals at the shaft head or inner tube, apply a generous amount of grease to the O-ring area during installation to facilitate assembly.
When installing the rotary joint, ensure that it is coaxial with the roller. If the shafts are not aligned, adjustment and locking should be performed at low speed (place a dial indicator in the vacant spot on the roller, rotate the roller, and record the stop position reached by the dial indicator pointer. Tighten the bottom bolt until the dial indicator pointer is in the stopping point.)
For rotary joints equipped with an observation port, ensure that the observation port is positioned at the 6 o'clock position.
For rotary joints with threaded plugs in the observation hole, the plugs in the observation hole need to be removed before use so that leakage can be detected in time and the bearing can be avoided.
For bi-directional rotary joints, the concentricity of the inner and outer pipes must be checked; an excessively long inner pipe, or a fit that is either too tight or too loose, can easily compromise the smooth operation of the rotary joint.
Precautions After Installing Rotary Joint
After installation, the rotary joint should flexible rotation, without any abnormal noises, binding, wobbling, or similar irregularities. The following are several points that require our attention:
An exhaust device should be installed at the highest point of the entire circulation system in the pipeline system to facilitate the removal of air from the rollers and pipelines. Otherwise, the system will make abnormal noises during operation, and in severe cases, it may even cause gas explosions at high temperatures.
Install pressure gauges upstream and downstream of the filter to monitor its condition; when the pressure differential rises, the filter screen must be cleaned or replaced.
Verify that the structure and length of the flexible tube are appropriate. The flexible tube serves to mitigate and dampen vibrations caused by pressure pulsations within the conveyed fluid. The impact of vibrations, concentricity, perpendicularity, and runout caused by the equipment during operation on sealing performance and service life. Its also have requirements; they should not be too long or too short. After installation, flexible tube should not be subjected to tension, pressure, or torsion. It is best to gently shake them by hand. Otherwise, the swivel joint will be pulled by the external force of the flexible tube, resulting in increased friction and accelerating the failure of the seal. The connection between the rotary joint and the pipe must be made through a flexible tube; it is strictly forbidden to connect the rotary joint and the pipe directly through a rigid pipe.
After the rotary joint is installed, except for a few series with small torque that do not require torsion, other series must be equipped with anti-rotation support devices to avoid the instantaneous starting torque when the rotary joint rotates causing the flexible tube to be stressed and fail prematurely. Furthermore, it is strictly prohibited to attempt to prevent the rotary joint from rotating by simply pulling the flexible tube taut; likewise, hoses or rubber tubing must not be used as substitutes for a dedicated anti-rotation support to counteract frictional torque.
Rotary joints for hot water and thermal oil must be heated gradually during circulation; the direct, rapid introduction of high-temperature media into the operating system is strictly prohibited.
Installation of Protective Devices: For high-speed, high-pressure, and high-temperature production li
nes, protective equipment must be installed on rotary joint and flexible tube to prevent accidents caused by leakage.
The Foundation for Long-Term, Stable Operation of Rotary Joint
While installation serves as the crucial first step toward ensuring the long-term, stable operation of a rotary joint, its ultimate effectiveness also depends on precise type selection, internal structural design, its application within the specific production line, as well as adherence to standardized operation and routine maintenance during subsequent use.
