Caesar II help informs that the negative mill tolerance is used in minimum wall thickness calculations. But I did some simulation using mill tolerance as zero e mill tolerance as a large number as 50% and the results are the same.

Does the negative mill tolerance has any influence on area and modulus for caesar II? And as consequence on stress?

For most piping codes addressed in CAESAR II, mill tolerance is used only in the minimum wall thickness check. It does not affect load or stress. In your simulation, check the Miscellaneous Data - Pipe Prop.#1. The last column shows the minimum required wall thickness. This will change as mill tolerance changes.

Hi Mr Diehl, thank you.

I am interested on the calculus for the stress ratio, since I am facing some trouble with non-expected low temperature from original design.

As I was writing down the text I realize that it is not informed to remove the mill tolerance for the nominal dimension less corrosion, erosion and mechanical allowances, according to Fig. 323.2.2B(a)(3) and according paragraph 320.1 (analysis of sustained loads – basic assumptions and requirements). So the mill tolerance it is not important for this verification, and as you said the mill tolerance does not affect load or stress also for B31.3 code.

z(sec.modul.) value change by mill tolerance at caesar calculation..so stress value change...
may be...

SORRY..I was mistaken. IT'S CORROSION..