Yes - I meant to write that the material is not permitted in Division 2.
You can look up the Code Case here - https://www.asme.org/codes-standards/publications-information/code-cases. If you are not able to access, please let me know, and I will upload the file here.
Yes - the criteria is...
1. Code Case 3090 covers this exact material (in the Grade 60-40-18) and the request for Design-By-Analysis. It needs to be ASME Section VIII, Division 1 construction, since the material is not permitted in Division 1.
2. All of the applicable parameters are provided in the Code Case.
3. Yes...
ASME Section VIII, Division 1 has no such restrictions. You are able to access Appendix 46, which will lead you to Division 2, Part 5 (Design-By-Analysis) either through U-2(g) or UG-16(a). From the perspective of the Code, you can avail yourself of that option.
If your customer is asking you...
You have hoop tension, but axial compression. Fix your boundary conditions, and your buckling behaviour will disappear.
Note that typical true stress-strain behaviour is that the curve will be perfectly-plastic after the true ultimate stress. Therefore, there will be deformation after. But...
By fixing both ends, you may be inadvertently causing some axial compression, leading to an actual fixed-fixed columnar buckling problem, combined with hoop tension.
Correct your boundary conditions.
Three comments/questions:
1) What are your boundary conditions on the ends of the piece of pipe? if they are fully fixed, then that would tend to give some erroneous answers.
2) Have you included the pressure thrust?
3) What have you done to initiate the failure in the middle like that?
FMJalink - when you speak of modification, are you referring to damage incurred in-service, or are you referring to purposeful modification, like a repair? If it is damage (of which the situation in this thread is a prime example), then the appropriate approach is to use a fitness-for-service...
I don't know. I haven't performed the necessary evaluation. I haven't seen any inspection records. I'm not willing to condemn (or approve) a vessel at first glance - that would be irresponsible of me as a professional.
It is up to the owner to determine whether the cost of such an...
r6155 - with all due respect, on what basis do you make that assertion? It has nothing to do with liking FEA or similar. I just think that an evaluation to determine fitness-for-service is warranted. That will include extensive inspection. I’ll trust the math, thank you very much.
1. Yes. We've done that type of work, too.
2. Gut feel says its a solid "maybe". What's the access like to get a high-quality laser scanning of the vessel interior?
3. Probably not.
4. This is a non-catastrophic buckling situation (a snap-through buckling, if you will). My bigger concern will...
Shell elements are really good for thin-shell analyses for demonstrating Protection Against Plastic Collapse, Protection Against Collapse From Buckling, and Protection Against Failure From Cyclic Loading: Ratcheting. They are not good for Protection Against Failure From Cyclic Loading: Fatigue...
