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#73249 - 05/06/19 07:15 PM Theoretical to CAESAR model spanning study.
Mattcaroni Offline
Member

Registered: 04/14/19
Posts: 3
Loc: philippines
Good day.

I am currently new on the software and would appreciate any comments and suggestion. As a new stress engineer I've read some subjects of the following:
-Roark's formula for stress and strain
-Stress Design of piping systems Mw-Kellog
-Pipe Stress engineering by peng
-Piping introduction to pipe stress kannappan


I am aware that based on my theoretical calculations from simply supported at both ends and uniformly loaded beam with both ends fixed does not provide any idea on how the orientation of the pipe should be. I am trying to use my computed length of supports around equipment with this formulas. However, when I try to model it through CAESAR II, the shown displacements under SUS only are way too conservative.


Any insights, ideas would be appreciated as I am aware I lack or missing certain understanding which leads to my confusion. Thank you.





Edited by Mattcaroni (05/06/19 07:20 PM)

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#73250 - 05/07/19 05:43 AM Re: Theoretical to CAESAR model spanning study. [Re: Mattcaroni]
anubis512 Offline
Member

Registered: 08/24/18
Posts: 48
Loc: USA
I'm having trouble understanding your issue. You did manual calculations for a pipe segment (presumably including only two supports) and you say the equivalent CAESAR II model is overly conservative (ie, displacements exceed your expected values)?

What kinds of supports? Temperature/pressure? What piping code?

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#73254 - 05/07/19 02:13 PM Re: Theoretical to CAESAR model spanning study. [Re: Mattcaroni]
Michael_Fletcher Offline
Member

Registered: 01/29/10
Posts: 710
Loc: Louisiana, US
I recommend you provide calculations so that we may better comment.

Please understand there are safety factors built into the software and the code that take account for real world effects, such as mill tolerance, uneven corrosion, etc.
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#73272 - 05/13/19 05:48 PM Re: Theoretical to CAESAR model spanning study. [Re: Mattcaroni]
Mattcaroni Offline
Member

Registered: 04/14/19
Posts: 3
Loc: philippines
I've been trying to reply to this thread with my calculations, however it keeps on saying. Encountered a problem. The reason reported was
Database error only visible to forum administrators
Please click back to return to the previous page. Does anybody know how to resolve this so I can post my calculations? THank you

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#73273 - 05/13/19 10:11 PM Re: Theoretical to CAESAR model spanning study. [Re: Mattcaroni]
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 5937
Loc: Houston, Texas, USA
Are you using the full "Reply" option instead of the "Quick Reply"? The full "Reply" has a File Manager option that should let you upload files.
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Richard Ay
Hexagon PPM (CAS)

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#73276 - 05/14/19 07:33 AM Re: Theoretical to CAESAR model spanning study. [Re: Mattcaroni]
Michael_Fletcher Offline
Member

Registered: 01/29/10
Posts: 710
Loc: Louisiana, US


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#73292 - 05/17/19 07:42 PM Re: Theoretical to CAESAR model spanning study. [Re: Mattcaroni]
Mattcaroni Offline
Member

Registered: 04/14/19
Posts: 3
Loc: philippines
My apologies if took quite some time for me to reply. As you can see I have a figure 1 and figure 2 model. I am not sure if which of the two is correct when modeling and looking for the deflection, however as you can see from load case SUS only, I only get less than 3 displacement with a 9 meter span, but in my calculation (theoretically) it is way far from 12.5 mm sag that I used. I think I'm missing some multipliers (safety factors) which were used by CAESAR II. Because I am having difficulties explaining my computations since it is too far from CAESAR II results. Any info will be greatly appreciated especially safety factors that I wasn't able to include. Kindly, include the reference or the title of the book if there are any for me to consider. Thank you.


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Edited by Mattcaroni (05/17/19 07:48 PM)

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#73295 - 05/20/19 08:29 AM Re: Theoretical to CAESAR model spanning study. [Re: Mattcaroni]
Vannella Offline
Member

Registered: 10/24/10
Posts: 35
Loc: IT
Mattcaroni,
normally the approach is considering piping "supported somewhere between simple support and fixed support".
These formula are valid for straight pipes. If you have bends, some reduction factors or additional equivalent lenghts have to be considered.
Please check the linear weight (looks a little too low) and do not forget mill tolerance, corrosion, insulation and valve weights if any.
By the way, yes: the theoretical calculated results are "often" overconservative if compared with CAESAR II calculated spans.


To investigate more, some good reference books are:
- Pipe Stress Engineering (Peng)
- Design of piping system (Kellogg)
- Introduction to Pipe stress analysis (Kannappan)

Corrado Vannella
www.vannella.com


Edited by Vannella (05/20/19 10:24 AM)

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