Some spring cans have a small deadweight mvmt.in the sustained case. Should this mvmt be added or subtracted from the total vertical thermal travel shown on the hanger data sheet? Seems like some companies disregard this mvmt. and others consider it.

You say the deadweight movement is small. I would disregard.
Some situations (e.g. very flexible pipe, very high load variation) will produce larger displacement here.
I know of a few users who will attempt to select a shorter range spring based on this reduced deflection. If that's your intent, you can use parts of your CAESAR II output to size your own spring and then specify the spring rate and theoretical cold load as model input.
We also have a Configuration switch that will allow you to include the proposed spring stiffness in the operating case which collects the proposed hanger's deflection - "Include Spring Hanger Stiffness in Hanger OPE Travel Cases".

Hi mul211
Spring deflection for sustain could be positive/negative depends on piping configuration, operating temperature, nearby support, selected spring load as already mention by Dave Diehl.

Yes some company follow the practice to maintain sustain deflection close to zero by manual spring selection.

To fill spring data sheet, I think we should mention actual spring deflection not relative deflection as mention by you to avoid any confusion for site operation.
If sustain deflection is really large we can better specify that also in data sheet.
Max load variation still need to keep within 25%.

Regards

Habib