| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | 2004, XM, V8i, CONNECT; |
| Area: | Calculations |
| Original Author: | Bentley Technical Support Group |
| Date Logged & Current Version | Aug. 2016 10.01.00.09 |
Problem:
For calculation of ASME NB-3683.7 Stress Indices does AutoPIPE use the Bend / Elbow properties (O/D and t), colored Grey in image below, or the preceding / post pipe properties (O/D and t), colored Red in image below?
Solution:
Creating a simple model with just a pipe and a bend. The model has two pipe IDs: PIPE and BEND.
Step #1: Initially set the pipe ID for both the pipe and the bend as "PIPE", analyze and take out the stress indices and bend input listing.
Step #2: Now select the bend only and change the pipe ID to "Bend", analyze and take out the stress indices and bend input listing.
Step #3: Notice that the flexibility factor in the bend data listing has changed. Also, the B2 and C2 factors to the Bend point (A02 N+ and A02 F-) have also changed between the reports.
Correct to say that the properties of the Pipe Identifier selected for the Bend are used to calculate the bend flexibilities and stress indices.
AutoPIPE uses the dimensional properties of the pipe ID assigned to the actual component (like bend). ASME NB mentions to use the equivalent pipe properties for stress indices calculations (NB-3683.1):
This requirement can then translate to other components like Tees and Reducers as well, for which AutoPIPE also take the actual dimensions defined for the component and not equivalent pipe. AutoPIPE does not currently keep track of information like “is the component a product following B16.9 and what is the manufacturer certified equivalent pipe for this product”.
A new enhancement has been logged under TFS-E528048 to provide a note to highlight that actual component dimensions are used for stress indices calculations. This note will appear in a future version of the program.
Conclusion:
The properties of the Pipe Identifier selected for the Bend are used to calculate the bend flexibilities and stress indices for the bend Near + and Far - faces.An enhancement as mentioned was logged for updating program help to explain which properties are used for calculation of bend stress indices and flexibility values.
See Also
ASME BPV-III-1-NB, AutoPIPE Nuclear Piping Code FAQ