Unrestrained Expansion Joint

The unrestrained expansion joint (EJ) is simply a bellows element attached to end fittings used to handle movements resulting thermal expansion or contraction of the adjacent piping. The single unrestrained expansion joint is the most basic Expansion Joint type, and can be used as the starting point once the need for an EJ has been established.

It is the most economical EJ product. However, the unrestrained EJ imposes pressure thrust force and deflection spring forces on adjacent anchorage and those forces must be accommodated by the system designer. Also, the amount of lateral offset is limited by the bellows length and often times the bellows length is severely limited by column stability.

metal expansion joint single


Movement Capabilities

The single unrestrained EJ has one bellows element designed to handle five degrees of motion including axial extension and compression, lateral offset in any direction, and angular movements imposed by the adjacent pipe or ducting. It is not intended to handle torsion.


  • Simplest, most economical design
  • Accepts axial, lateral, angular movements
  • The universal EJ can be designed with a very low lateral spring rate, and high movement capacities
  • Versatile and common throughout all industries


  • Low Cost
  • Handles all types of movement
  • Assurance: successful track record in countless applications

Universal Un-Restrained Expansion Joint

Universal Unrestrained Expansion Joint

If the lateral offset requirement is large, a universal unrestrained EJ is appropriate. The universal EJ has two identical bellows elements that handle lateral offset by tilting of the bellows element rather than shearing. So the individual bellows elements can be quite short and, therefore, stable while handling large lateral offsets.

The amount of lateral offset that can be accommodated is only limited by the distance between the bellows elements and the overall length of the assembly. The separation of the bellows elements also results in a very low lateral offset spring rate. Just like the single, the unrestrained universal EJ imposes pressure thrust forces on adjacent anchors



The unrestrained EJ is appropriate for any application where pressure thrust can be handled by external anchorage. The universal unrestrained EJ is appropriate for large lateral offset requirements and wherever a low lateral offset spring rates is required.

Range of Design & Operating Conditions:

  • Full vacuum to 2000 psig depending on size
  • Cryogenic to 1600°F
  • Sizes from 1” NPS to > 240” NPS

Accessories & Options:

  • NDE/QA
  • Flow liner
  • External cover (Shroud)
  • Tie rods/Limit rods/Control rods
  • Hinge/Slotted Hinge
  • Gimbal
  • Ply Testable
  • Red-Top©
  • Multi-Ply Bellows
  • Purging
  • Insulation
  • End Connections
  • 2 Ply Test Kit
  • On Site Service

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