The load case editor allows for the hanger travel case to be 'Ignore' or 'As design'.

The help facility explains that when the user wishes to include the stiffness of the selected (?) in the operating (?) for hanger travel case and iterate to a solution.

First of all I do not understand the above sentence. Please explain.

Next, I bumped on a calculation with the "as design" option.

What is the benefit of this option?
What are the pro's and con's?

Best regards,

Timo

Typically hanger design is a "two load case, one pass" affair: restrained weight to get the hot load, then a free thermal to obtain the travel. Once you have these two values, you pick the hanger. At this point, the hanger preload and stiffness are inserted into the model and "your" load cases are analyzed.

But what happens if the hanger stiffness is significant compared to the stiffness of the nearby piping? Sometimes the hanger affects the behavior of the piping system.

Some people/organizations want to perform a second free thermal with the hanger inserted. If the resulting travel results in a different spring being selected, then the new spring is inserted and the process is repeated (this is the iteration you refer to).