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#56073 - 09/05/13 02:07 AM Buried piping stress analysis
A.P.Kichambare Offline
Member

Registered: 04/16/09
Posts: 5
Loc: Madrid, Spain
Just now started buried piping analysis. little bite confuse.

I model all line which are buried and went to underground pipe modeler input, where i have inserted all parameters like axial, lateral, upward downward, up, down loads and stiffness, as well as friction coefficient, soil density, buried depth, angle,
yield displacement factor, overburden compaction. Then i run converted all model.

My question is do i need to give any restrain in piping model?

How we normal pass this information.
_________________________
ashutosh

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#56075 - 09/05/13 05:46 AM Re: Buried piping stress analysis [Re: A.P.Kichambare]
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6194
Loc: Houston, Texas, USA
If you define a "soil model" then you don't need to define the stiffnesses and loads, CAESAR II will compute and apply those values.

The Buried Pipe Modeler adds the necessary soil restraints along the pipe. You don't need to add additional (buried) restraints unless you have a thrust block or an underground vault - items CAESAR II wouldn't know about.
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Regards,
Richard Ay - Consultant

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#56162 - 09/12/13 01:04 AM Re: Buried piping stress analysis [Re: A.P.Kichambare]
A.P.Kichambare Offline
Member

Registered: 04/16/09
Posts: 5
Loc: Madrid, Spain
Hey richard thank you very much. i was on leave after that discussion, could not reply you back.
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ashutosh

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#64399 - 09/21/15 11:15 PM Re: Buried piping stress analysis [Re: Richard Ay]
kannapiran Offline
Member

Registered: 12/29/14
Posts: 6
Loc: dubai
Hi Richard,

16" pipe, design temp=80 degC, Design pressure=27 bar

Using B31.3 code, After creating buried piping (file name added with B), stress failure is happening under expansion case.
Stress is passing only when
Providing the loop (or) Providing Anchor at the center of the long run pipe.


Using B31.4 code, After creating buried piping, stresses are failing in Operating, Expansion & occasional cases.

i have given correct soil properties only as per client specification.

Kindly advice the right approach to use UG pipe analysis in CAESAR-II in both ASME codes.


Thanks,
Kannapiran.K

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#64406 - 09/22/15 07:48 AM Re: Buried piping stress analysis [Re: A.P.Kichambare]
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6194
Loc: Houston, Texas, USA
The requirements (Code equations for stress and the allowable values) are different for B31.4 compared to B31.3. The choice of piping code should be defined in the project specifications - this is not an option to you.

The fact that your system passes some load cases in one Code but the same cases fail in a different Code is not surprising. Analyze your system based on the requirements of the project. For the specified Code, determine the cause of the failure and resolve the issue (just like always).
_________________________
Regards,
Richard Ay - Consultant

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