Liners
Internal liners can be used to either protect the metallic bellows from erosion or reduce turbulence across the bellows.
Covers
External Covers providing a protective shield that spans the length of the bellows. Covers prevent direct contact with the bellows, offering personnel protection, as well as protection to the bellows from physical damage such as falling objects, weld splatter or arc strikes. They also serve a purpose as insulation of the bellows.
Limit rods
Tie Rods or Limit Rods are designed to contain pressure thrust. The rods will have nuts or stops on the ends of the assembly to limit the overall length. When an expansion joint is designed for pure lateral offset the rods are defined as Tie Rods can find on this page. If the expansion joint is intended to absorb axial motion as well as lateral offset, the rods will have outboard stops to limit the expansion joint to the installed length plus any specified axial extension. This is defined as a Limit Rod.
Particulate barriers/purge connectors
In systems that have a media with significant particulate content (i.e. flash or catalyst), a barrier of ceramic fiber can be utilized to prevent corrosion and restricted bellows flexibility resulting from the accumulation of the particulate. Purge connectors may also be utilized to perform this same function. Internal liners must also be included in the design if the expansion joint includes purge connectors or particulate barriers.
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