Can old Appendix 1-10 still be used for large openings? 2

[RadiateurFou]

Hello,

I understand that Appendix 1-10 was usefull to evaluate forces and moments for large openings. I also understand that it was deleted, but can it still be considered as a "recognized and generally accepted
method" to be used according to U-2(g)?

Thanks in advance

 

[TGS4]

No.

Appendix 1-10 was deleted because the method in ASME Section VIII, Division 2, Part 4.5 is based on the same method. Therefore, if you need to use something like Appendix 1-10, and you are fabricating to ASME Section VIII, Division 1, then use UG-16(a) and Appendix 46 to access the VIII-2 rules.

 

[RadiateurFou]

It is indeed based on the same method. However the 25% rule of 4.5.17 is a problem, as most of our nozzle fails to this rule.

Does that mean the only solution then is to go with Part 5?

Thanks for the quick answer and sorry for my late one.

 

[RadiateurFou]

Not that i'm complaining i do stress analysis as a job, just trying to understand the whole picture

 

[TGS4]

4.5.17 is for external pressure If that truly is your situation, then the old Appendix 1-10 wouldn't have helped you anyway. But yes, above the limit stated, you need to use Part 5.

Speaking of external pressure, please make sure to use the latest version (2023) when designing for buckling. The buckling rules changed significantly, and it is best to use the 2023 rules.

 

[RadiateurFou]

4.5.17 refers to compressive stresses more than just external pressure. As we're working at cryogenic temperatures, I'm guessing that the thermal contraction creates compressive stresses.
This in turn makes 4.5.17 relevant for us, even though there is no external pressure.

Thank you for the notice on the new buckling methods, we've actually been looking at it for the past few weeks. That's for another subject, but do you have any papers to recommand explaining why this change has been made? Is it to consider the plasticity effect on buckling?

 

[TGS4]

As we're working at cryogenic temperatures, I'm guessing that the thermal contraction creates compressive stresses.

Please check that assumption. I do not think that this is correct.

but do you have any papers to recommand explaining why this change has been made?

PVP2020-21112

 

[RadiateurFou]

I reread 4.5 and i think the problem is with 4.5.15. External loads can only be considered with WRC 107/297 or numerical analysis. As WRC is limited to a ratio of d/D < 0.5, for larger openings numerical analysis and thus Part 5 becomes the only solution.

 

[TGS4]

Please note that WRC 537/297 is supplemented by ASME STP-PT-074, which has a larger range of d/D ratios.

 

[RadiateurFou]

I will look into it

 

[RadiateurFou]

Ratio can go up to 0.7 with STP-PT-074. Better but still not enough for 50% of our nozzle i'd say. So Part 5 it is

 

[IdanPV]

Does ASME STP-PT-074 can be used for local stresses due to external loads caused by square attachments?

 

[TGS4]

IdanPV - ASME STP-PT-074 is for cylindrical nozzles only.

 

[jt1234]

If any one go to any plant, refinery or petrochemical plant, you will see a lot of T junctions, same diameters or header with branches. The sizes can be huge as I have done more than 100" pipe or you can call it ductwork. If by B31.3 there is no issue to reinforcement the junction by its own criteria. Why so much trouble in pressure vessels with such d/D limit. Keep in mind, stress is stress. material is material, Material in itself can not tell if the stress is B31.3, Div.1, Div 2. What human can make is only the safety factor. So why not adopting B31.3 for large opening in pressure vessels, and as needed, adjust safety factor. I am all for for one code like other countries instead of so many codes and papers scattering here and there. Who knows it all ? 35 years in this industry, I am sick and tire of this kind of thing.

 

[RadiateurFou]

True but B31.3 requires flexibility analysis with stress intensification factor to calculate stresses at junction. You have to consider a whole lot of load cases, so it can be pretty time consuming.
In that the simple but limited opening reinforcement calculation of div VIII section 1 can be easier i think.

 

[jt1234]

Radia I do not agree with your opinion. The world shall have only one universal method to calculate the local stress, that is by FEA, However, that may be time consuming and cost too much such that simplified method was invented like WRC 107 or in any articles. However, B31.3 which deals with so many T junctions in all kinds of d/D ratio is the way to go. You forgot that the loads at the junction is from piping flexibility analysis, and B31.3 will be able to take care of that to tell you if junction reinforcement is ok or not.

So, by adopting B31.3 approach, input design condition, external nozzle loading from pipe stress engineer or from project spec, and the geometry of the intersection, the junction can be immediately evaluated. So no more bothering WRC, STP, or whatever articles that not many people familiar with. The whole purpose is to just to calculate the stress with a universally available approach and can be commercialized in software besides FEA.

Think about the universally used Zick analysis for saddles, which is a simplified method, otherwise you will need to use FEA to prove the design.

 

[TGS4]

jt1234 - if the approach that you are advocating is as simple as you make it out to be, and as technically robust as you think that it is, then I challenge you to write a technical paper about this approach, get it peer reviewed, and then present it - the ASME PVP Conference is the perfect venue for that. If you can do that, get it through the peer review process, and present it at the Conference, then I will personally bring it as an action at the (appropriate subcommittee of the) ASME Section VIII Code Committee to change the Code (Section VIII, Division 1, or 2, as appropriate/applicable. With your 35 years of experience, I suspect that putting together such a paper should be well within your wheelhouse.

The 2025 ASME PVP Conference will be held July 20-25, 2025 in the beautiful city of Montreal, QC. The conference website is [URL unfurl="true"]https://event.asme.org/PVP[/url]. I anticipate that the PVP2025 call-for-papers will come out in August or September of this year, with the Abstract Deadline typically being near the end of October. After you have submitted your abstract, please let us know, so that we may await your technical paper and attend your presentation at the conference.

 

[jt1234]

TGS4, thanks very much. I will certainly consider it.