What causes leakage in a rotary union?

 

 

One of the primary causes of leakage in a rotary union is seal wear. Seals are designed to prevent fluids or gases from escaping. Continuous rotation and exposure to harsh operating conditions gradually degrade the seals, leading to leakage. High pressure, temperature fluctuations, and abrasive particles in the fluid accelerate this wear.

How to mitigate seal wear

Choose high‑quality seals that are compatible with the operating conditions.

Inspect and maintain the seals regularly to detect early signs of wear.

Provide proper lubrication and filtration to minimise the impact of abrasive particles, thereby extending seal life.

 

 

Incorrect installation is another common source of leakage. Mis‑alignment, over‑tightening, or under‑tightening can damage the seals.

Best‑practice installation

Follow the manufacturer's instructions carefully, paying particular attention to alignment and torque specifications.

Clean all mating surfaces thoroughly before assembly to remove dirt or debris that could affect seal performance.

Use the correct tools and techniques to avoid damaging the seals.

 

Using a fluid that is not compatible with the materials of the rotary union can cause chemical reactions, leading to seal degradation and leakage.

Ensuring compatibility

Consult the supplier's specifications to confirm that the fluid is compatible with the seals and other components.

When in doubt, conduct compatibility tests before the fluid is introduced into service.

 

 

Excessive pressure can exceed a seal's design limits, while extreme temperature changes cause the seal to expand or contract, both of which may lead to failure.

Control strategies

Select a rotary union that is rated for the maximum pressure and temperature expected in the application.

Install pressure‑ and temperature‑control systems to keep operating conditions stable.

 

 

Particles, dirt, and debris in the fluid can damage seals and other components, resulting in leaks.

Preventing contamination

Install adequate filtration to remove contaminants from the fluid.

Perform regular cleaning and maintenance of the rotary union.

Use high‑quality fluids and lubricants that generate fewer particles.

 

 

Poorly designed seals, incorrect clearances, or manufacturing errors can also cause leakage.

Choosing a reliable supplier

Purchase from a reputable manufacturer that uses high‑quality materials and advanced production processes.

Review the supplier's quality‑control procedures and request performance test data or sample units before full‑scale purchase.

 

 

 

Issue	Recommended Action
Worn or damaged seals	Replace with seals that match the operating conditions and fluid type.
Improper installation	Re‑install following the OEM's alignment and torque guidelines.
Incompatible fluid	Switch to a fluid approved for the seals and components.
Pressure/temperature spikes	Add pressure‑ and temperature‑control devices; verify that the union's ratings exceed the maximum expected values.
Contamination	Install or upgrade filtration; perform routine cleaning.
Design/manufacturing flaws	Source the union from a proven supplier; request test samples before full purchase.

 

 

Leakage in rotary unions can cause costly downtime, higher maintenance expenses, and safety hazards. By understanding the various causes-seal wear, improper installation, fluid incompatibility, pressure/temperature fluctuations, contamination, and design/manufacturing defects-and applying the corrective measures listed above, you can dramatically reduce the risk of leaks and keep your equipment running reliably.

If you are experiencing leakage in your rotary unions or need assistance selecting the right unit for your application, please contact us. Our engineering team is ready to provide personalized solutions and technical support.