Hi stephen

When I have been to my first site survey, I was suprised that piping had acted almost as CAESAR II result. So I suspect there is something wrong in the piping system.

You need to check your CAESAR II input first, check you input all the condition correctly.
And then, check the site if it has been installed as drawing. Sometimes construction crew can make mistake while installing supports.

Also, I assume the system has a desuperheater. If so, the line condition can be vary by this equipment, also there could be lots of requirement demended by vendor. You need to check that with mechanical guy.

After investigating, everything is set accordingly, you can restrict system as SND said by using hold down support or guide, stopper.

It is all my opinion and you should talk with your LE first.