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#36505 - 06/30/10 02:35 AM Slug Load Calculation at blind flange
jad Offline
Member

Registered: 12/29/09
Posts: 6
Loc: NO
Hi everyone,

What inclusion angle to be used for the calculation of slug load on blind flange?
We currently use 180deg but can't figure out why and where to find related reference. Is it due to the returning of the flow upon hitting the blind?

Need your inputs and knowledge to enlighten this matter.

Thank you in advance.

Regards,
jad

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#36510 - 06/30/10 04:22 AM Re: Slug Load Calculation at blind flange [Re: jad]
MoverZ Offline
Member

Registered: 11/22/06
Posts: 1195
Loc: Hants, UK
What equations are you using for this ?

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#36511 - 06/30/10 04:35 AM Re: Slug Load Calculation at blind flange [Re: MoverZ]
jad Offline
Member

Registered: 12/29/09
Posts: 6
Loc: NO
We used the formula from Caesar technical reference:
F = ρ*v^2*A*[2(1-cosθ)]^1/2

and adding the DLF gives:

F = ρ*v^2*A*[2(1-cosθ)]^1/2 * DLF

Thanks again,

jad


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#36517 - 06/30/10 06:29 AM Re: Slug Load Calculation at blind flange [Re: jad]
MoverZ Offline
Member

Registered: 11/22/06
Posts: 1195
Loc: Hants, UK
Firstly, the equation you are using relates to changing direction of a moving mass and so far as piping is concerned, the flowing mass needs to go somewhere having changed direction. You will get a similar result from centifugal force and change of momentum equations. Both assume continuity.

If a slug hits a blind, where does it go afterwards ?

Are you assuming that the pipe is empty (a vacuum ??) upstream of the blind prior to arrival of the slug ? Or is there some gas being compressed ahead of the slug ? If so, where does it go to ?

This does not seem feasible to me.



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#36520 - 06/30/10 07:20 AM Re: Slug Load Calculation at blind flange [Re: MoverZ]
jad Offline
Member

Registered: 12/29/09
Posts: 6
Loc: NO
The blind flange is in close proximity with the tee, as shown on the attached sketch.

I assume that the moving mass will be going back and follow the flow( exiting on the branch)as shown on the picture, hence, there is a continuity.







Attachments
barred tee with blind flg.JPG



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#36533 - 06/30/10 10:26 AM Re: Slug Load Calculation at blind flange [Re: jad]
MoverZ Offline
Member

Registered: 11/22/06
Posts: 1195
Loc: Hants, UK
The worst case is just like a bend in terms of established flow. What happens first depends on compressability of the blind leg.

You need a dynamic simulation here. You might consider BOS Fluids from Paulin research Group.

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#36545 - 07/01/10 01:45 AM Re: Slug Load Calculation at blind flange [Re: MoverZ]
jad Offline
Member

Registered: 12/29/09
Posts: 6
Loc: NO
Well thank you very much Moverz for the input, I really appreciate that. It seems like we really need BOS Fluid to solve this. Hope to attend the next training course of PRG.

Regards,
jad


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