Hi Pickles,
Look at each and every hanger and get the hot load data off the manufacturer's name plate. Use that in your CAESAR II model. Now, if these things have many years of "experience" there will be an internal (to the hanger) friction that will have to be evaluated. While you are walking down the system and the hangers, examine each hanger and note its condition (corrosion, loose parts, missing hardware, evidence of someone "mucking about" with the elevations or the settings. AND DO NOT overlook the fact that "constant force" hangers can be "adjusted" in the field to change their reactive (supporting) force - look for evidence of this too. Have a look at ASME B31.1, Appendix "V" (roman numeral) for a list of what to look for and for a check list to use "whilst" you are out there looking.
At least 50 percent of the work in evaluating existing support systems is done
on-site.
Regards, and good luck.
_________________________
John Breen