Expansion joint angular stiffness with tie rod

Hi,

I am just curious about the angular stiffness in expansion joints. Some vendor catalog has values for angular stiffness. My question is that if there is a tie rod in my expansion joint , will my EJ be able to rotate according to my desired angular stiffness values? Or will my tie rod limit the rotations of my EJ so is it better to not use the angular stiffness values?

Thanks,
ELI

Hello leo81457

In the case of a heat exchanger, the expansion joint cannot suffer angular rotation, and it is not subject to torsion. We do not do the analysis according the EJMA. The expansion joint remains aligned. The tubes of the fixed tubesheet exchanger hold the shell in alignment.

Hard to say without knowing your approach to modelling/evaluating the expansion joint.
The tie rods will control the end-to-end movement of your joint but the joint will still bend (twice) to suit the tie rod motion. The tie rod motion is also affected by friction in these connections. This friction can change the load at which the joint starts to move but the final position of the joint (and the transferred load) will be related to the joint bending stiffness.
Many vendor catalogs display a "bending stiffness" that is not appropriate for use in a beam-based analysis (like COADE's CAESAR II). Watch how you use that number.