Dec 2014, AutoPIPE V8i 09.06.01.10
ASME B31.3-2010 Occ Allowable is incorrect in AutoPIPE V8i 09.04.xx.xx, why?
There is a known issue that was logged against that version of the program:
TFS-D138808 (CAE-TR-10782) - B31.3-2010 Occasional allowable may be unconservative for T<Tcr or Tcr=0
This has been fixed already been fixed, AutoPIPE V8i 09.05.01.xx and Higher.
Select from one of the 4 possible workarounds
1. Define a user allowable stress for sustained combinations using “Code Comb.” tab of Load Combination dialog.
2. When there is no Tcr value specified for a material in the library, update the library with a valid Tcr value. Otherwise, open the Pipe Properties dialog for the affected Pipe ID, change the pipe material to another material and then change it back to the original material by clicking “OK” on the dialog. Note that user allowable values, if previously entered, will be reset.
3. Change Tools> Model options> Results> Use Alt. Occ. Allow, check OFF.
4. Upgrade to a newer version (AutoPIPE V8i 09.05.01.xx and Higher).