Rotary Unions, Swivel Joints,
Air Breather Filters, Flexible Hoses


Designed and Manufactured in the UK, Supplied Worldwide for over 75 years.

05:07:50 GMT




Reasons for Premature Failure of a Rotary Union

Wednesday 27th January 2021

Ensuring your Rotary Union is installed correctly.

Following on from our previous blog about Extending the life of your Rotary Union, you will also need to ensure that you carry out regular maintenance.  In addition, it is vital that the Rotary Union is being used correctly and that it suits your application. Below are some examples of things which you should consider.


Incorrect fitting of flexible hoses – Getting this right will ensure that there is no adverse load on the Rotary Union. See our previous blog for further information.


Abrasive particles in fluid – These particles could be rust particles from old pipework or contaminated water through open systems. The fluid should ideally be filtered to a maximum of 40 microns, if there is still a problem with premature failure due to excessive seal face wear, alternative seal face materials can be used.  If you let our Technical team know the full working conditions of your application, they can then ensure the correct Rotary Union and seal materials are used.


Over pressurising the Rotary Union – This can be caused by closing valves whilst the fluid is still hot and preventing flow through the Union, this can potentially crush the Bellows and cause leakage when the Union is used again.


Mixing incompatible lubricants – If you use an incompatible lubricant it can cause early bearing failure.  Mixing incompatible greases can have dire consequences, they may react together and cause a separation of the base oil or oils from the thickeners of the two greases.  Whether two different greases are compatible will depend mainly on the compatibility of the thickener used in the two greases.  Filton use Total Multis Complex EP2 within our standard Unions, this is a Lithium based grease.  Should you have any concerns regarding compatibility and lubrication periods, Filton recommend you contact your Grease supplier for assistance.


Using Rotary Unions as steps/ladders – Sometimes we have heard of Rotary Unions being used as steps to reach other parts of the machine.  Firstly, this is not advised for health and safety reasons and secondly the potential loads applied to the Unions could cause failure.


Our Technical Team are on hand to help with any queries you may have. 


Contact our Technical Team either by phone on +44 1926 423 191 or by email at