As given in Caesar II on line documentation :
____________________________________________________________________
Add Torsion in SL Stress
Some piping codes include torsion in the sustained and occasional stresses by explicitly including it in the stress equation (i.e. B31.1), and some don't include torsion in the sustained and occasional stresses by implicitly calling for "longitudinal stresses" only (i.e. B31.3). Setting the Add Torsion in SL Stress directive to Yes forces CAESAR II to include the torsion term in those codes that don't include it already by default. Setting this directive to Default causes CAESAR II to use whatever the currently active piping code implies. In a sustained stress analysis of a very hot piping system subject to creep, it is recommended that the user include torsion in the sustained stress calculation via this parameter in the setup file.
___________________________________________________________________

As given for hot piping user shoould include torsion in sustained stress calculation. then what is criteria for selecting hot piping. means lines having temp above 300 deg C should be considered as hot piping ?
Means i want to know what is temperature range should be set to include torsion in sustained stress calculation.

if anyone knows regarding this then i request to please explain anbout it.

thanks in advance.

regards,
ajay