How do I properly model tubing on CAESAR II?

If you're referring to tubing as small diameter seamless metal piping with custom bends, it's common practice not to. Usually the cut-off in my experience is an inch in nominal size.

yes, that is what I am referring to. 3/4" seamless bent tubing. I don't understand why you wouldn't be able to model it on CAESAR.

Your units file (xxx.FIL) has a switch to use or not use nominal pipe sizes and the default setting is to use nominals. You type in the nominal OD and CAESAR II will replace your value with the actual OD.
But tubing actual OD, oftentimes, matches this entered nominal and will convert your data. It appears, then, that you cannot properly specify these tubes.
To fix this, you would create a new units file where you turn nominals "OFF".

where do you go to turn nominal off?
thank you

I am modeling both pipe and bent tubing on the same piping systems. in other words the piping system I am modeling goes from pipe to tubing. Are you saying I cant model them on the same file?
thanks,
Mary

Mary,

1. Close the piping input editor.
2. Go to the "utilities tab."
3. Create/Review Units -> copy a units system you're using, but change the setting to specify manual input of OD. Save it as something meaningful to you.

On a new file, use this new file.

On existing files, use the "change model units" on the same tab on the ribbon interface to change this setting.

You CAN model them all in the same file. Unfortunately, this setting is stored in an awkward location "under the hood."

Consequently, once you change it, any changes to sizes of piping requires you to key in the OD manually... unless you change the "units" back.

If you turn off the "nominal switch", you will have to enter actual outer diameters. When the switch is off, entering a diameter of "8" puts "8.00" in the diameter field. If you wanted "8.625", you must enter "8.625".

You have nominal diameters either "on" or "off" for a given model.