| Applies To | |||
| Product(s): | AutoPIPE, | ||
| Version(s): | 2004, XM, & V8i | ||
| Environment: | N/A | ||
| Area: | Model Options | ||
| Subarea: | |||
| Original Author: | Bentley Technical Support Group | ||
Comments, Questions, and Answers about using Tools>model Options> Results> "Sustain Margin" in AutoPIPE
Item #1:
I am analyzing my model to ASME B31.1 and noticed when looking at stresses the asterix appearing noting the sustained load margin has been included. I have looked into this and found it in the code and have seen that autopipe by default automatically goes to a higher allowable when the expansion stress exceeds the default allowable. When the sustained load margin is included i.e. Eq(1B) from ASME B31.1 102.3.2 you can get an allowable exceeding yield. Should this allowable be limited to 90% of yield; based on the 90% yield limits in 102.3.3(B)? This is for a test so surely during operation yield should not be exceeded
Answer: See AutoPIPE online help for details on this feature and defualt settings. Excerpt from the online help:
This field is enabled for all piping codes except BS806, BS7159, CSA-Z662 Offshore, B31.3 Appendix P, B31.4 Offshore, B31.8 Offshore, MITI, JSME PPC, and General. The default for this field is "E".
You have the option to change this setting and save it to a default file to be used when starting a new file in AutoPIPE (see Save Default).
In addition, see the respective piping code section, ASME B31.1-2010, 102.3.2 - Limits for Sustained and Displacement Stresses, there is no mention in this code section on how to handle a scenario where the allowable exceeds the material yield value. Therefore, Bentley cannot answer specific on how your company should handle such situations, consider using sound engineering judgement or contact the ASME board for a direct answer to your code question.
See Also
External Links
Bentley Technical Support KnowledgeBase
Comments or Corrections?
Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!