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

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

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

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

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

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

thank you Dr DK

nola

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

When there is FV in Limpet coil how shall be the Test Pressure Calculated on Shell side.

Rajesh

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

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

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.