A longstanding problem with any hydraulic system is that they eventually will leak. Many times, United Equipment Accessories (UEA) is contacted when a potential customer is having leaking issues with another supplier's rotary union. Situations like this provide an opportunity for UEA to demonstrate our proven process of delivering excellent customer service to help alleviate their problem.  We stand behind what we do. Our commitment is to diligently work with the customer to find the source of the issue as quickly as possible.

Finding the source of the leak and reducing the likelihood that it will happen again takes investigation. The best way to determine the reason behind the leak is to have the rotary union in question sent to UEA for evaluation. In some cases, a field visit is appropriate to inspect the issue.

Here are some of the potential causes for rotary union leaks and solutions that we have identified to mitigate these issues:

• The spool may have sharp edges that cause the seal to get tiny cuts. We ensure that the machined edges where the seals are inserted are smooth to prevent any microscopic cracks in the seals.
• Seals can become pinched or folded over during installation. We pay careful attention to how seals are installed to prevent this.
• The spool and housing are not concentric or outside the tolerance zone. We perform quality checks during the machining process to ensure concentricity.  
• Seal grooves may not be concentric. Quality checks are performed during machining for concentricity.
• The age of the seals and storage humidity impacts the seal's performance. Seals must be kept in consistent humidity and be used before the expiration date.  
• The seals may have compression issues due to material composition or storage of the seals. We work to find the right seals for your application and rotary union design, and we store the seals in the appropriate conditions.
• Completed rotary unions stored in a horizontal position can put an undue side load stress on the seals.
• Leaks can be missed when there is a lack of proper testing. We perform high- and low-pressure tests under rotation to significantly reduce the likelihood that a rotary union will have quality issues after it leaves UEA.

While this list may not be exhaustive of every problem, these are the issues that appear to be the most common for rotary unions. To learn more about our quality rotary union solutions, contact us for your custom solution today.