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#17051 - 04/03/08 02:08 PM Line Modeling with SIF
psaen Offline
Member

Registered: 08/26/06
Posts: 5
Loc: America
In my personal experience I try to model only relevant items in a calculation, sometimes when I am calculating a 16” pipe I don’t include the 2” lines associated to that pipe.

- What do you think about this assumption?

- Does anybody include a SIF without modeling the branch line (i.e. the metioned 2" pipe or lower diameters)?

-Is it correct for CAESAR II to run a model which has a SIF and do not include the branch?

Thanks in advance

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#17053 - 04/03/08 06:05 PM Re: Line Modeling with SIF [Re: psaen]
Bob Zimmerman Offline
Member

Registered: 12/29/99
Posts: 197
Loc: Houston,TX,USA
Including these SIFs and small branches can sometimes cause inexperienced stress engrs to take the WRONG corrective action, e.g., unnecessariy reroute the pipe.

Paulin Research's (www.prg-software.com) last Webinar brought up this vey subject; webinar042 "What is 100% of the Allowable Stress for Pipes and Pressure Vessels"

Note that per B31.3, a 24"x18" WOL SIF is equal to a 24"x3" WOL SIF. The SIF is a function of the Header size only. This is the code we use and obviously this is "silly".

Mr. Paulin quoted WRC 329 Para. 4.4 Run Moments where it stated to the effect '...for this example the code requirements are obviously silly ...(SIFs for a 24"x3/4" branch SIF applying to the Run pipe)... use JUDGEMENT...'

Try to register for these webinars there are only a few more scheduled. Tony Paulin and his team are doing a great free service to us stressmen.
_________________________
Bob Zimmerman, P.E.
Vice President of The Piping Stress International Association (The PSI)

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#17054 - 04/03/08 06:17 PM Re: Line Modeling with SIF [Re: Bob Zimmerman]
John C. Luf Offline
Member

Registered: 03/25/02
Posts: 1110
Loc: U.S.A.
It has been my pleasure to know Tony for many years, he is beyond any doubt one of the premier experts in the field and is under contract to bring order to chaos for branch SIFS in B31.3.
_________________________
Best Regards,

John C. Luf

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#17056 - 04/03/08 07:45 PM Re: Line Modeling with SIF [Re: Bob Zimmerman]
bom Offline
Member

Registered: 06/23/07
Posts: 285
Loc: Manila, Philippines
Last webinar of PRG was very interesting but Does it have audio explaination??

Regards!
_________________________
BOM

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