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#21708 - 10/21/08 06:25 AM B31.4 STRESSES
piper_78 Offline
Member

Registered: 04/16/08
Posts: 10
Loc: India
Hi Pipers,
I suppose I may be shooting this again. But I have gone through the forum and still searching for the concrete answers.I am analysing one system which specifically a pig launcher and pig recieving system with somewhat system underground. Since this is 24inch dia pipeline with a design temp of 93 and working temp of 65 deg. We were analysing this line in Ceasar-II and since its a crude transportation line so we have to follow B31.4 as the applicable code.
Now the question is that whether we have to test the stresses in operating case also. This is what one of the thing I found out in the forum. Refer the attached link of the forum.

http://www.coade.com/ubbthreads/ubbthreads.php?ubb=showflat&Board=1&Number=1907&Searchpage=7&Main=566&Words=%26quot%3Ballowable+stress%26quot%3B&topic=0&Search=true#Post1907.
But once i run the system it says no code check stress checked in operating case.
Please suggest.
Regards
piper78

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#21710 - 10/21/08 07:06 AM Re: B31.4 STRESSES [Re: piper_78]
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
Pipeline Codes (like B31.4) evaluate "restrained" and "unrestrained" piping. Restrained piping does entail an operating stress, while "unrestrained" piping does not.
_________________________
Regards,
Richard Ay - Consultant

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#21740 - 10/22/08 08:57 AM Re: B31.4 STRESSES [Re: Richard Ay]
Claguzpipe Offline
Member

Registered: 10/20/08
Posts: 3
Loc: Chile
And what about Fac value on this configuration under 31.4

10anchor 20guide 30guide 40 anchor
__/____________-__________-___________/_____
- -

I mean between node 10 and 40 pipeline is restrained
but, should i consider nodes 20 and 30 unrestrained?
10-20 Should i use fac =1?
20-30 Should i use fac= 0?
30-40 should i use fac=1

Best regards
Claudio

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#21744 - 10/22/08 11:33 AM Re: B31.4 STRESSES [Re: Claguzpipe]
Richard Ay Offline
Member

Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
Typically the only time you're "restrained" is when you are buried and have developed sufficient axial restraint. CAESAR II can determine this for buried piping, so you don't have to make that decision.

_________________________
Regards,
Richard Ay - Consultant

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