| Applies To | |||
| Product(s): | AutoPIPE | ||
| Version(s): | 2004, XM, V8i | ||
| Area: | Results | ||
| Original Author: | Bentley Technical Support Group | ||
| Date Logged & Current Version | Aug. 2015 09.06.02.06 |
Problem:
The main load case that we are concerned is Equiv2 or Tensile 2 which captures the compliance to CSA Z662 Clause 4.7.2.1. it is assumed that it is only capturing the bending stresses due to thermal expansion.
Solution:
We have investigated the issue and the user's observations are correct. AutoPIPE only adds the axial force due to pressure when pressure extension is enabled. The other forces and moments do not include the effects from pressure extension in the default code combination Equiv2 for CSA Z662 code. This is also true for other codes, and is by design. AutoPIPE B31.8 code may be an exception as it always includes a pressure case in the default code combination.
To be able to include the effects of pressure extension other than the axial force, the user can include the desired pressure case in the default code combination for Equiv2. This will include the pressure extension effects to moments as well.
Another follow up question may be the difference observed between the General Stress Report and Equiv2 stress results (different for the user model). These can be matched by setting the Result Model Option "Total stress (OCT/Max)" to M, which represents Max Shear Stress. AutoPIPE calculates Equiv2 stresses using Tresca stresses, and for General Stress Report the value displayed is Max Shear Stress = Tresca Stress / 2.0.
Note, For Equiv2 load combination, the axial force from other load cases is always included and is independent of the Result Model Option "Include axial force".
See Also
CAN/CSA-Z662 Piping Code Calculations