Problem:
When using modeling to ASME B31.1 2022, why is the value for Sustained Torsional Moment Index (It) for Threaded Joints set to 1.0 on the dialog (shown below)
The code clearly states:
Referring to ASME B31J Table 1-1 for threaded connections (Sketch 5.1)
Sus Tors Index = 0.75x it = 0.75 x 2.3 = 1.725
Therefore, why does AutoPIPE show .0 when it should be 1.725?
Solution:
Whenever there are questions about a dialog, best advice is to always start by thoroughly reviewing AutoPIPE help on the dialog. This review should include reading all notes.
While performing this review in AutoPIPE help, scroll to the bottom for general Notes, and specifically note #4:
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- 4. For joint types other than User Defined, the Axial SIF, Axial Index, and Torsional Index are not automatically calculated by the program and are set to a value of 1.0 when inserting the User Joint & SIF at a point. However, program does apply applicable piping code clauses (e.g. Axial SIF is set as Out-of-plane SIF for B31.1 2020 for all components other than bends) when generating code compliance reports.
What does this mean in simpler terms?
When the user is entering data for Joint Type and User SIF for some joint types, "Sus Tor Index" is not calculated at this time.
This field is dependent on what we call a post process calculation specifically settings choices made on the Results Model Options dialog.
Therefore, this field default value is 1.00. HOWEVER, when reviewing the code calculations, the correct Index is calculated and used by the program when generating results.
Please be aware that the Results model option "Apply B31J Gen. note (d)" will influence the computation of this value. It is essential for you to resolve the status of this setting (e.g., On or Off).
Upon further consideration, the dialog value of 1.0 is leading to confusion. Maybe a new feature be incorporated into the program to show "Auto" in place of 1.0. This would be similar to the Code compliance allowable setting labeled as "Automatic."
By selecting Automatic rather than a specific value, the user will review the report for the value calculated by the post processor. based on Results Options settings.
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