Applies To
Product(s):	AutoPIPE
Version(s):	ALL;
Environment:	N/A
Area:	Calculation
Original Author:	Bentley Technical Support Group
Date Logged & Current Version	March. 2017 11.00.00.22

Problem:

ASME 2010-2011a states:For NB-3653.7 "Thermal Stress Ratchet. For all pairs of load sets, the value of the range of ΔT1 cannot exceed calculated allowable"

Does Autopipe Nuclear calculates this for ALL possible load pairs and not just those used in the fatigue calculation. Some load pairs will not occur in the fatigue calculation due to numbers of cycles being used up for some load cases and not being combined with other load cases that have more cycles.

Solution:

Yes, all combinations are included in the check.  After performing a simple check that demonstrates that the maximum DT1 range came from a load case that was removed from the fatigue analysis, procedure below:

Step #1: Create a Stress Summary with 3 cases in the same index. 

Step #2: Run the analysis and check the Stress Summary and Fatigue reports.

Step #3: Two load cases will combine and will be removed, as the cycles are the same.  The 3^rd will also be removed as no load cases remain to be ranged with.  

Note: If 3^rd case is set up so it has a DT1 value that will contribute to the maximum range, this will then be seen in the stress report.

See Also

ASME BPV-III-1-NB, AutoPIPE Nuclear Piping Code FAQ

Bentley AutoPIPE