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#34085 - 04/05/10 04:19 AM D/t >100 and SIF
Tengku_Syahdilan Offline
Member

Registered: 12/26/09
Posts: 56
Loc: Indonesia
Dear Richard and others,

For piping system with D/t > 100, App.D ASME B31.3 SIF doesn't cover this, and also CAESAR II, so can i overwrite the SIF value in CAESAR II ? because at this time i have this problem where my piping system is 30" Sch 5S material A358-304 and there are many Tee, and also Repad. When i modelling this offcourse CAESAR will not give a "right" value of SIF, so what is the way to overwrite the SIF Value her to achieved good result?
Thanks.
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Tengku_Syahdilan
"From Failure we Learn"

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#34086 - 04/05/10 04:27 AM Re: D/t >100 and SIF [Re: Tengku_Syahdilan]
Tengku_Syahdilan Offline
Member

Registered: 12/26/09
Posts: 56
Loc: Indonesia
I'm sorry dear Richards and others, i'm quite rush to post this question, when before i should use "search" tools, and there are many post about this discussion...so once again sorry, i will read other post firts AND ALSO coade Newspaper about modelling large D/d Tee...hope i'll find my answer...
Thank you all........
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Tengku_Syahdilan
"From Failure we Learn"

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#34103 - 04/05/10 07:29 PM Re: D/t >100 and SIF [Re: Tengku_Syahdilan]
Tengku_Syahdilan Offline
Member

Registered: 12/26/09
Posts: 56
Loc: Indonesia
Dear Richards and other,
I have read through discussion about D/t>100 and read COADE Newsletter about Modelling Large D/d Tee, but there is a problem, how about an Elbow with D/t>100, i don't ask about the correlation of it with ASME Code, what i ask is can we implemented the same theory to modlling elbow with D/t>100, if can't, how can i overwrite SIF value that i got into CAESAR II input?
I have try through the"Environment tab, Review SIF at Bend Node to overwrite my SIF, but it can't.....so is there any otherway...hope that you can show me more light into this..........
Thanks............
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Tengku_Syahdilan
"From Failure we Learn"

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#34104 - 04/05/10 08:18 PM Re: D/t >100 and SIF [Re: Tengku_Syahdilan]
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
You simply type in the SIF value you want, into the field on the dialog. The bigger issue is "where do you get the number from?"
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#34130 - 04/07/10 03:43 AM Re: D/t >100 and SIF [Re: Richard Ay]
Tengku_Syahdilan Offline
Member

Registered: 12/26/09
Posts: 56
Loc: Indonesia
I haven't get the SIF Value yet, but i planning to use FE/Pipe....
My question if i do not make any change and just accept the result that CAESAR give, in what range the error of the calculation?
Because i have read in FE/pipe manual, that an incorrect modelling of elbow or straight pipe with Large D/T can be lead an error reult in order of 25%.
I'm not worry with intersection such as Tee and others because we already know how to do a conservative modelling for this problem, but for elbow/bends? since CAESAR always give this warning even if i have put the value of SIF that later i will get from (FE/PIPE). Is right way to modelling the elbow with single or double flange? can be this minimize the error?


Edited by Tengku_Syahdilan (04/07/10 03:45 AM)
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Tengku_Syahdilan
"From Failure we Learn"

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#34141 - 04/07/10 06:55 AM Re: D/t >100 and SIF [Re: Tengku_Syahdilan]
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
Quote:
if i do not make any change and just accept the result that CAESAR give, in what range the error of the calculation?

I can't say. If the Code knew that, they would adjust the equations to consider your D/t ratio.

Quote:
Is right way to modelling the elbow with single or double flange? can be this minimize the error?

CAESAR II gives this warning because the Codes don't address this condition (D/t > 100). CAESAR II does what the Code does. If the Code doesn't know how to do something, then neither does CAESAR II. The presence of flanges won't alter the fact that the Code equations don't address D/t ratios in excess of 100.
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#42306 - 04/08/11 12:02 PM Re: D/t >100 and SIF [Re: Richard Ay]
EnriqueReyes Offline
Member

Registered: 04/08/11
Posts: 1
Loc: other
Iím doing some research about SIF with D/t> 100. Iíve done a static structural analysis in ANSYS based in the correlation of SIFís with stress indices using these considerations:
1. Tangents pipes of 3 times the outside diameter
2. i=(C 2*K2)/2
3. 90ļ Elbows and 45ļ Elbows
4. Material: Carbon Steel ASTM A234
Iím Concerned because Iíve obtained an error of 26% between FEA results and those obtained using the B31.3 equations. Did I do something wrong?
Because Tengku_Syahdilan said that he read that ďan incorrect modeling of elbow or straight pipe with Large D/T can be lead an error result in order of 25%Ē
Besides I know the importance of the pressure in pipes with large D/t so Iím thinking analyze the models with internal pressure for study their behavior. Any recommendations for that?

I'll appreciate your help.THANKS


Edited by EnriqueReyes (04/08/11 12:05 PM)
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