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#418 - 07/30/01 11:33 PM WRC 107 Module -Trunnion check
NEELAM RAJA Offline
Member

Registered: 04/21/01
Posts: 62
Loc: India, Australia(Perth)
Can the WRC 107 Module be used to check local stresses due to TRUNNION/ROUND ATTACHMENTS on a pipe surface.
Further ...
If an attachment is welded to a pipe and loadings on the attachment are known ,using a stress analysis program,should one add the local stresses caused due to the attachment to the stresses evaluated by the stress program.
i.e. suppose a piping stress run on Caesarii gives a longitudinal stress value of Sl_c2 in the stress output at a point with an axial stop(realised thro a trunnion welded to the pipe).
Is it not logical to add the stress caused due to the trunnion loading eccentricity to this Sl_C2 and compared with Sh.
.
Can someone throw some light onto this?
_________________________
Neelam Raja

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#419 - 07/31/01 01:47 PM Re: WRC 107 Module -Trunnion check
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
Probably not. Here are the reasons:
  • WRC107 has a number of geometric limitations (for nozzles on cylindrical vessels). Your trunnion geometry probably exceeds these limitations.
  • The stress computed in CAESAR II is the stress along the centerline, based on the forces and moments (along the centerline). Adding these global analysis stresses to (empirical) local analysis stresses is a questionable undertaking.


I feel for a proper analysis of this situation, you're going to need a finite element solution.
_________________________
Regards,
Richard Ay - Consultant

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#420 - 08/02/01 02:50 PM Re: WRC 107 Module -Trunnion check
Jim Wilcox Offline
Member

Registered: 12/20/99
Posts: 46
Loc: Calgary, AB, Canada
Neelam, I think that if you had SIF values for the elements that intersect, you could build the model in CAESAR II with the trunnion, and apply the SIFs in the appropriate locations. The main problem with this is that the codes don't give us the SIFs for this type of intersection.
I would recommend looking into FE/Pipe. It is a relatively inexpensive FEA program that has tools specifically dedicated to trunnions and a variety of other piping/vessel components. It will give you the stress results, as well as code allowables and SIFs.
For more information, here is a web link: http://www.codecad.com/PRG.htm
The following images were captured from the program:


_________________________
J.

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