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Participant

Join Date: Aug 2017
Posts: 2

ASME VIII Div 1 Corner Joints UW-13.2 (c), (d)

08/03/2017 5:14 AM

Hello, people!
I'll be very appriciated for your assistance to comprehend where did I get wrong with understanding of design rules of corner joints type (c) and (d) shown in fig. UW-13.2.
Based on the results of strength analysis the thicknesses of header elements are
tubesheet - 36 mm; top/bottom plates - 36 mm, end plates - 36 mm.
According to notes to type (d)(the corner joint of end plates):
a + b ≥ 2∙ts, whereas a ≥ ts, tp=min(6 mm, ts).
In that case b=ts and tp=6 mm. Besides, the size of the ledge under the end plates rim is 2 mm.
To meet the notes requirement the thicknesses of the tube sheet, top and bottom plates have to be increased:
b + tp + 2 = ts + tp + 2= 36 + 6 + 2 = 44 mm.
And here, I think, I made a mistake, cause if I apply this logic to the type (c) joint, than it appear that we can't weld plates of equal thickness!

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Guru

Join Date: Jan 2010
Location: Mineral wells Tx
Posts: 613
Good Answers: 34
#1

Re: ASME VIII Div 1 Corner Joints UW-13.2 (c), (d)

08/03/2017 8:28 AM

Really, I do not understand your reasoning. Anyway, check the next page, it is an excellent/examples guide for what you are looking for:

"Finite Element Analysis (FEA) is used to investigate reasons why ASME VIII-1,

FIG.UW-13.2, does not permit certain joint configurations for the attachment of

welded unstayed flat heads:

1. Joint Orientation: The eccentrically attached weld allows the joint to

open under pressure.

2. Fatigue Life: The peak stress created at the weld root limits the fatigue

life.

3. Weld size: The weld size is insufficient to satisfy the Code’s geometric

requirements....................."

http://www.keydesigneng.com/KEY026SampleDiscussionUW131headscomparison.pdf

Also, if you have time, check the oficial ASME VIII INTERPRETATIONS. In many of these volumes there are references/Questions about UW-13.2 like:

INTERPRETATION ASME VIII 1- 04- 44 and 46

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Participant

Join Date: Aug 2017
Posts: 2
#2
In reply to #1

Re: ASME VIII Div 1 Corner Joints UW-13.2 (c), (d)

08/03/2017 9:26 AM

Thank you for you advice, I'll try to skim through this Interpretations, maybe I'll be lucky. Actually, I read this document you linked to yesterday and it doesn't concern the weld joints I was talking about. The joints that resemble to (c) and (d) types are widely applied in production of headers for air-cooled heat exchanchers and able to work safely under the inner pressure up to 25 MPa and even more.

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Commentator

Join Date: Jun 2007
Posts: 67
Good Answers: 5
#3
In reply to #2

Re: ASME VIII Div 1 Corner Joints UW-13.2 (c), (d)

08/04/2017 8:53 AM

I believe that you did the math correctly and that, when the plates are identical or similar in size, the logic of UW-13.2 pushes you to use (a) or (b), which have an internal fillet weld.

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