Internal Liners — The Expansion Joints Blog


Expansion Joint Protection Components

September 28th, 2010 Comments off

U.S. Bellows offers many accessories to protect the bellows and extend the life of your expansion joint. This article briefly describes a few of them including protective covers, internal liners, limit rods, hinges and purge connections.

Protective Covers

Installation of a protective cover on a 30" diameter spent catalyst standpipe metallic expansion joint with pantographic linkage. * External covers protect the bellows element from mechanical damage, during shipping, maintenance activities, and plant construction
* Cover may be used for the application of insulation when the ductwork is insulated
* Protective covers are provided in removable and non-removable configurations
* The picture shows the installation of a protective cover on a 30″ diameter spent catalyst standpipe metallic expansion joint with pantographic linkage

Internal Liners

Internal liner to protect convolutions * Internal liners, also known as “Internal Sleeves” and “Telescoping Sleeves,” extend the life of a metallic expansion joint
* Protects the convolutions from direct flow impingement, which can cause flow-induced vibration
* Standard liners are fabricated from 300 series stainless steel (optional materials include Inconel 625 and Inconel 600)

Limit Rods

Expansion joint with limit rods Limit rods are used to limit axial expansion or compression to prevent the bellows from over-compression. Limit rods are designed to absorb the pressure thrust of the expansion joint in case of anchor failure.


Hinges permit angular rotation in one plane only by the use of a pair of pins through hinge plates attached to expansion joint ends. Hinges and hinge pins are designed to restrain the thrust of the expansion joint due to internal pressure. Hinges can also be designed to carry piping loads.
Expansion joint with hinges to prevent angular rotation in one plane * Angular rotation in one plane
* Eliminates pressure thrust forces
* Transmits external loads
* Prevents torsion on bellows
* No main anchors required
* Minimum guiding required
* Low forces on piping system

Purge Connections

Expansion joints with purge connectors to blow out collected material * Used in systems where sediments can collect between the outside of the internal liner and the inside of the bellows element
* Purge connectors can be added to the upstream end of the liner
* Inert gas or air can be injected to periodically blow collected material out or can be continuously supplied during system operation

Contact Us: +1 (281) 241-9418 Toll Free: (855) 591-0906 Fax: +1 (713) 731-8640
Our Parent Company: Piping Technology Pipe Supports, Pipe Clamps, Pipe Hardware & Insulated Pipe Shoes
Fellow Subsidiaries: Sweco Fab: ASME Vessels, Pig Launchers, Duct Work, Strainers & Spectacle Blinds
 Pipe Shields: Pre-Insulated Pipe Supports, Slides, Guides & Anchors

Fronek Anchor/Darling
: Snubbers, Sway Struts & Sway Braces

Copyright © 2018  U.S. Bellows, Inc. All Rights Reserved. Privacy Policy