All times are UTC + 2 hours




Post new topic Reply to topic  [ 12 posts ] 
Author Message
 Post subject: half pipe jacket
PostPosted: Sat May 22, 2010 2:26 pm 
Offline

Joined: Sat May 22, 2010 2:07 pm
Posts: 3
hi,
The rules in App EE of VIII-1 for half pipe jackets are given only for the design condition where there is positive pressure inside the head or shell
And positive pressure inside the half pipe jacket

what is the procedure with the situation of negative pressure inside the shell/head and
negative pressure inside the half pipe jacket ?

For example
Vessel pressure: -1+3 Barg
Half pipe Jacket pressure: -1+6 Barg

thanks
Nola


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Mon May 24, 2010 3:28 pm 
Offline
----------------
----------------
User avatar

Joined: Sat Dec 01, 2001 1:00 am
Posts: 869
Location: Essen, Germany
Nola,

In this case you need to consider every combination of pressures.

This means you need to calculate the jacket for -1 and for 6 bar.
You need to calculate the vessel for -1 an for 3 bar.

And you need to calculate the common elements, the jacketed shell portion, for 7 bar external and for 4 bar internal side pressure.

That should do it.

DK


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Mon May 24, 2010 5:01 pm 
Offline
----------------
----------------

Joined: Tue Dec 01, 2009 1:55 pm
Posts: 270
Location: DESCON Engineering Limited, Pakistan
Dr. DK,

How to get the value of K if the shell thickness is greater than 3/16". As all Figures EE-1 to EE-3 provide the values of K up to a shell thickness 3/16".

_________________
Thanks & Regards,
Nasir
Welding Engineer
DESCON Engineering Limited.
Lahore, Pakistan.
Mobile # 0092-336-4145402


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Mon May 24, 2010 5:10 pm 
Offline
----------------
----------------

Joined: Tue Dec 01, 2009 1:55 pm
Posts: 270
Location: DESCON Engineering Limited, Pakistan
Sorry, I mean how to get K values if shell thickness is less than 3/16" ?

_________________
Thanks & Regards,
Nasir
Welding Engineer
DESCON Engineering Limited.
Lahore, Pakistan.
Mobile # 0092-336-4145402


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Mon May 24, 2010 10:53 pm 
Offline

Joined: Sat May 22, 2010 2:07 pm
Posts: 3
Hi Dr DK,

Lets me se if get you right.

In order To calculate the Shell external pressure :
Ill need to put 0 barg in shell side and 7 barg in half pipe side.
The result Ill get will be the Shell thickness to Withstand Jacket Pressure (6 barg) + full vacuum from shell ?

In order To calculate the Shell internal pressure :
Ill need to put 4 barg in shell side and 0 barg in half pipe side.
The result Ill get will be the Shell thickness to Withstand Jacket full vacuum + 3 barg from shell ?

Regars
Nola


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Wed May 26, 2010 12:48 pm 
Offline
----------------
----------------
User avatar

Joined: Sat Dec 01, 2001 1:00 am
Posts: 869
Location: Essen, Germany
Nola,

The entry depends on your computer program.
Some programs are based on absolute pressure, some on gauge, some are considering multiple chambers some require each chamber to be designed separately.

My recommendation was based on manual calculations, and the design pressure you enter into the formula (UG-27 for ex.) But when you do your Computer Program Verification (see Foreword of the Code) you will find out how the program translates the Code formula into paper.

DK


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Wed May 26, 2010 6:23 pm 
Offline

Joined: Sat May 22, 2010 2:07 pm
Posts: 3
thank you Dr DK

nola


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Thu May 27, 2010 6:59 am 
Offline

Joined: Fri Apr 23, 2010 11:49 am
Posts: 6
Dr. DK,

While designing Shell for External pressure with Limpet Shall limpet be considered as Stiffner so that Design length of Shell will decrease while designing at Full vacuum.

Regards


Rajesh


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Mon May 31, 2010 6:27 am 
Offline

Joined: Fri Apr 23, 2010 11:49 am
Posts: 6
When there is FV in Limpet coil how shall be the Test Pressure Calculated on Shell side.

Rajesh


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Tue Jun 01, 2010 9:20 pm 
Offline
----------------
----------------
User avatar

Joined: Sat Dec 01, 2001 1:00 am
Posts: 869
Location: Essen, Germany
Rajesh,

for the hydrotest please refer to UG-99 (e),

for the design of the shell and possible stiffening effect, this depends on the actual design method and tool, U-2(g) will possibly be the clause you end with.

DK


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Thu Sep 22, 2011 11:42 am 
Offline

Joined: Wed Sep 21, 2011 6:38 pm
Posts: 1
Dear Dr. Koelbl,

I was searching the forums for a solution to a problem answered by you in this thread. Thank you very much for your earlier responses.

I had a couple of questions.

1) If the code and App EE of VIII-1 does not expressly address the design of vacc vessels with half pipe or angle limpets on shell, is there any document or interpretation which specifies the rules to be used? Our vessel designs and drawings are to be approved by 3rd party inspecting agencies like TUV and we fear that they may ask for Code references in this case.

2) If vertical angle limpets are used, can these also be used to provide additional stiffening to the shell thus reducing shell thickness? Once again where in the Code can I find reference to this issue.

Thanks in advance.

Pradeep


Top
 Profile  
 
 Post subject: Re: half pipe jacket
PostPosted: Fri Nov 04, 2011 12:38 pm 
Offline
----------------
----------------

Joined: Fri Jul 09, 2010 7:57 am
Posts: 79
Limpet or Half Pipe Coils are a form of Jacket which are attached directly to Shell . Still they are not considered as Stiffeners .Hence Code seems to be silent on limpets.

For other forms of Jacket , rules are provided to take credit for the Stiffening effect. e.g. Mandatory Appendix 9.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 12 posts ] 

All times are UTC + 2 hours


Who is online

Users browsing this forum: No registered users and 0 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group

phpBB SEO