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zhafir
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Join Date: Jun 2010
Posts: 26

How to Verify Ovality of a Large Thin Horizontal Vessel?

06/01/2010 10:31 AM

Hi all,

I just want some opinion about the vessel that I currently design.

The ID is 9000mm and T.L-T.L is 38500mm and the min thk due to internal pressure is 24mm. Additional info is D.T is about 315°C and D.P is 0.575 N/mm2.

Since the vessel will be supported by two saddle and there is no external/internal stiffening ring due to zero external pressure, I am worry that due to weight of the vessel itself , the bending stress at the mid span and also at the horn of the saddle might make cylindrical shape of the vessel became oval and that is something I really want to avoid.

I already perform some manual calculation as BS 5500 Annex G and Zick study but both of them just show the stress but not the indication of change in shape for the vessel.

I am looking for some suggestion on how to approach this matter, do I need to perform modelling or someone has some formula to verify this situation.

thanks and have a good day

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Abdel Halim Galala
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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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Good Answers: 248
#1

Re: How to Verify Ovality of a Large Thin Horizontal Vessel?

06/01/2010 11:10 PM

You can proceed such a design for two saddle supports using any method, but you have to check for stresses in vessel due to those two saddles using ZICK's Method.

• See this file, and note the serious effect of dimension A (distance between saddle support and T.L): Design_of_two Saddle_Supports for a Pressure Vessel.

• Or see the whole design of a pressure vessel as per ASME code, Section VIII, Div. 1: Pressure_Vessel_Design_Calculations per ASME VIII, Div.1.

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Abdel Halim Galala
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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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#2
In reply to #1

Re: How to Verify Ovality of a Large Thin Horizontal Vessel?

06/02/2010 5:57 PM

• With respect to the permissible and acceptance criteria of ovality (out-of-roundness) for cylindrical, conical, and spherical shells, as per ASME code, Section VIII, Div. 1, see Para. UG-80 :

a. At any cross section (including head-to-shell junctions): Dmax. - Dmin. ≤ 1 % D

b. When the cross section passes through an opening: Dmax. - Dmin. ≤ 2 % D

Where,

Dmax. = Max. inside diameter of shell

Dmin. = Min. inside diameter of shell

D = Shell nominal diameter at the cross section under consideration

• See link for UG-80__Out_of_Roundness_as_per ASME VIII, Div.1.

.....................................

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wijeesh
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Engineering Fields - Mechanical Engineering - New Member

Join Date: Apr 2008
Location: India
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#4
In reply to #2

Re: How to Verify Ovality of a Large Thin Horizontal Vessel?

10/31/2011 2:40 AM

Dear Sir

How this out of roundness in calculated in Div 2. Is there any graph for the same like in div1.

Regards

Vgsh

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Abdel Halim Galala
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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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Location: Cairo, Egypt
Posts: 1733
Good Answers: 248
#5
In reply to #4

Re: How to Verify Ovality of a Large Thin Horizontal Vessel?

11/05/2011 4:12 AM

Sorry, I am not interesting at Div. 2.

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zhafir
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Posts: 26
#3
In reply to #1

Re: How to Verify Ovality of a Large Thin Horizontal Vessel?

06/04/2010 4:33 PM

thanks so much for the reply mr.abdel

now i am more clear about the method and hopefully the vessel is not going to be out of roundness....

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