Dear stress community

How can I solve following problem:

A pipeline (6”) near a control valve suddenly began to swing in an
area of 14,6 m without any restraint. As an easy solution the operator
wants to build in a support at operating temperature because the pipeline cannot be shut down. Unfortunately the pipeline has at the restraint point thermal displacements
(dx=20mm, dy=2mm,dz=38mm).
When the piping system cooles down , there will be some stresses and forces in the system.

A better solution would be to install the restraint or a viscoelastic damper in the cold system.

But this is at this time not possible and not the question.

Is it possible at all to model the described scenario of changing the boundary conditions at operating calculation run with caesar II loadcases and how are the stresses to evaluate?

It sounds like his article may be of some help to you.... http://www.coade.com/newsletters/oct96.pdf

A Gerb
http://www.gerb.com/en/arbeitsgebiete/arbeitsgebiete.php?&ID=121&kategorie=8

visco elastic damper might be a good choice and could possibly be instaled in the hot displaced condition just check to make sure that it displacements back to ambient do not exceed the travel for it.

Of course this damper will work only if the swing or movement is fast enough to engage the fluid in the damper.

Some other questions to explore are...
1)If the system has been in sevice previously and suddenly starts vibrating why the sudden change?

2)If it is flow induced vibration can the system be redesigned to eliminate the vibration?