by FSA member Lloyd Aanonsen

Thermal forces are considerably greater than the control unit's strength because the cross-section of the steel pipe is greater than that of the control rods. If the pipe thermally contracts beyond the expansion joint's allowable expansion limit, both the control unit and the expansion joint will fail. This type of failure is often incorrectly attributed to manufacturing defects in material or workmanship, but it is actually caused by over-extension. Careful attention must be given to selecting an expansion joint that will accommodate the predicted thermal movements.


The primary functions of elastomeric expansion joints include absorbing all directional thermal movements and reducing noise and vibration. They are also used to resist system shock, relieve pipe and anchor stresses, compensate for misalignment and provide access to piping and equipment. With a basic understanding of both the expansion joint functions and the requirements of the overall piping system, a reliable piping system can be obtained. Consultation with a reputable expansion joint manufacturer is also beneficial in the design and selection process.


For more information on this topic, see the newly published FSA Technical Handbook Non-Metallic Expansion Joints and Flexible Connectors - Seventh Edition.

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