Appendix 13 - circular section with central dividing plate

[tigny]

Hi,

Sorry for the repost (first posted in Boiler and Pressure Vessel engineering)
[ol]
[li]In chapter 13-4 of Appendix 13 (ASME VIII section 1), it is stated that ...The joint efficiency factor E shall also be applied to the allowable design stress for evaluation of the calculated bending stress Sb at the location of the joint only. See 13-l(d), 13-5 footnote 1, and 13-8(b).

Does this mean that primary bending stress shall be compared to allowable SE?
So far I thought only primary membrane + bending should be compared to the allowable, in general 1.5SE

Please find below a link to my file.

[/li]
[li]An other question on the same subject,
what category would you apply to the welds of central dividing plate?

Category C: any welded joint connecting one side plate to another side plate of a flat-sided vessel.

(typography is not clear in the code; does it lack some comas?)

or Category D: Category D. Welded joints connecting communicating chambers [...] to flat sided vessels

[/li]

[li]Also, does anyone know of other code or method to assess the stresses in vessels of circular cross section with central dividing plate [with differential pressure]:

References for this, as I know, are:

* ASME VIII division 1, appendix 13;

* TEMA code (RCB-9-13);

* Roark & Young, chapter 10.10, tables 26 8a et 26 9 Bending of uniform-thickness plates with straight boundaries
[/li]
[/ol]


Yours,

tigny

 

[prex]

No file on that link.
1.Can't really see your point. Code may be badly worded, but the meaning is clear:
-you need to account for E in determining the allowable: in other words the allowable is SE
-the limit stays on membrane + bending (no meaning for a limit on bending only) and is 1.5SE as you state
2.I vote for Cat.C. What difference does this classification make for your case?
3.The treatment of App.13 for the central dividing plate is complete and is based onto a continuity stress analysis in the style of App.4 of Div.2. Can't propose anything different: TEMA and Roark give formulae for flat plates, but there is nothing on the interaction of the plate with the shell. What are you exactly looking for?


prex

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[tigny]

Hi Prex,

thank you for your answer.
I try to put the link again.

My problem is that I think E=1 (see point 3 below); which I have some difficulties to accept!

1. OK, I will remove my check of bending stress only.

2. I ask this because (I don't have the code while replying now) I think in UW-12 table, there is a difference in the E factor between C and D category;

3. My concern is mostly to assess the stresses in the weld between the plate and the shell.
There are so many footnotes and links to other chapters, concerning welds, that I feel lost in the code; however, there is a footnote: note 1 from 13-5: ' Use E = 1.0 far Category C and D joints that are not...'

I think it applies to my case; I think the rest of the sentence says something like "the resistance of the weld is ok provided you respect the welds arrangement/size as in UW-13".

Therefore I ask confirmation that I can use E=1.

yours truly,

tigny

 

[prex]

Your joint is not a butt joint, it is a corner or angle joint: so footnote 1 to 13-4 applies. For the efficiency of an angle joint I think that some guidance is in UW-13.

prex

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