In ASME ND equation 10 code stress combination for thermal case . Autopipe combines zero moment case. I could not get more detail or explanation of zero moment case from Autopipe work book. Can you please explain what is zero moment case and which code clause states this requirement to be included in the stress calculation?
For Equation 10 in the Stress Summary dialog, the zero option indicates the inclusion of a zero moment option corresponding to zero pressure, zero moment and room temperature.
It represents the cold condition (i.e. the starting point for stress ranging). It is included for convenience where a specific cold condition load case has not been created.
ASME BPV-III-1-ND, AutoPIPE Nuclear Piping Code FAQ