Internal liners in expansion joint

Internal Liners in Expansion Joint 

       In a pipeline system,we commonly add internal liners in expansion joint to protect the bellows better,the medium can be air, gas, oil, water etc in various environment.

And internal liners are recommended where the follwing conditions:

1. In steam lines where the velocity of flow would set up vibration within the bellows.

2. In compressed air pipes.

3. In ducts carrying exhaust gases.

4. Where the flowing media is abrasive;i.e.,contains solid particles which could damage the inside of the bellows. 

5. Where turbulent flow exists;for example,when bellows are positioned downstream of an elbow,valve or adjacent to recirculating pumps.In such a case,due to the possibility of vibration being set up within the bellows,it is often necessary to fit heavy liners.

6. If liners are required in system which are subject to flow reversal when the flow is high velocity,it is often necessary to either fit thick carbon steel liners or strenthen the leading edge of the thin gauge stainless liners normally used.The effects of the flow would otherwise cause the leading edge of the sleeve to vibrate and shatter.

   
   

      In summary,internal liners in bellows expansion joint are very necessary when the flow rate exceeds 10ft./sec.They are available in slide-in "top hat" designs,or welded-in designs.