Rotary Joint Common Problems

A rotary joint is a mechanical device used to convey media. It delivers steam, thermal oil, water, and air from a stationary pipeline into rotating equipment.

As an important role in the industrial production section, the proper use of rotary joints is of paramount importance. However, in actual production processes, merely selecting the appropriate threads and types is far from sufficient. Even if your rotary joints have been correctly installed and maintained, you may still encounter a range of issues during operation. These problems often stem from diverse causes and can arise at various stages throughout the entire service life. In the following sections, we will assist you in gaining a deeper understanding of these issues and provide you with corresponding solutions.

Measures for Rotary Joint Issues

Rotary Joint Fluid Leakage

Bearing Failure & Noise

Causes:

Bearing damage and abnormal noise in rotary joints are typically associated with irregular mechanical loads and poor lubrication conditions.

Specifically, common causes of premature bearing wear include a lack of concentricity between the rotary joint and the equipment shaft, excessive shaft runout, or insufficient overall concentricity. These issues subject the bearings to uneven loads during operation, generate continuous vibration, and accelerate the wear of the rolling elements and raceways.

Furthermore, while bearings are primarily designed to accommodate radial and axial loads, conditions such as twisting, misalignment, or improper length selection of the flexibel tube can impose additional lateral loads and bending moments on the rotary joint. When combined with factors such as inadequate piping support or the failure of anti rotation mechanisms, these issues frequently result in eccentric loading on the bearings, thereby further increasing operational noise and reducing service life.

Solutions：

The installation alignment of the rotary joint, support structures, and flexible tube should be periodically verified to eliminate eccentric loading, while ensuring that the grease supply remains adequate and clean, thereby extending the service life of the bearings.

Rough Rotation or Sticking

Causes:

If a rotary joint operates unevenly or exhibits intermittent sticking, it is typically attributed to excessive internal friction.

Insufficient bearing lubrication is one of the most common causes of this issue. Poor lubrication increases friction and temperatures, leading to a gradual rise in the rotary joint's rotational resistance.

Concurrently, overtight installation can exert excessive preload on the bearings and seals, thereby hindering their proper functioning. Furthermore, abnormal wear on sealing surfaces, as well as the deformation or damage of internal components, can increase contact friction and impede the rotary joint's normal rotation.

The jamming caused by foreign objects is another significant factor contributing to rotary joint sticking. Contaminants such as rust, welding slag, scale, or fibrous debris that infiltrate the joint's interior can clog fluid passages or become lodged between moving parts, ultimately causing rotational difficulty or even complete seizure.

To prevent such issues, it is essential to regularly remove accumulated internal impurities, including rust, scale, and fibers, to keep fluid passages and moving parts clean. Worn or damaged components should be replaced promptly.

Additionally, during installation, one must avoid excessive tightening to ensure that all components maintain appropriate operational clearances, thereby minimizing frictional resistance and guaranteeing the smooth operation of the rotary joint.

Rotary Joint Overheating

Causes:

Overheating is one of the more common issues encountered during the operation of rotary joints; it typically results from excessive heat generation or insufficient heat dissipation.

When lubrication is inadequate, friction significantly increases between the moving components, such as bearings and seals, located within the rotary joint, thereby generating a substantial amount of frictional heat.

Additionally, malfunctions in the cooling system, excessively high media temperatures, or compromised heat dissipation capabilities resulting from seal failure can all cause heat to continuously accumulate within the joint.

In the case of steam rotary joints, poor condensate drainage constitutes another primary cause of overheating. For instance, a clogged siphon pipe, a malfunction in the condensate system, or an obstructed drainage channel can all reduce the efficiency of heat removal, leading to a sustained rise in local temperatures.

If the rotary joint remains in an overheated state for an extended period, the materials comprising its various components may soften or even seize up. This accelerates the aging of seals and the wear on bearings, ultimately leading to the premature failure of the joint.