WRC 107/297 for Nozzle at Tower Head

Dear All,

I have this problem in one of our project where we have a tower haed nozzle connection to piping that have to be analyze for Local Stress.
And WRC 107 & 297 in CAESAR II can't do this because the centerl line between tower/vessel and nozzle Can't be Colinnier.
So we do with FE-Pipe to get the flexibility then input this flex to CAESAR II.
My question, is there any reason why CAESAR II can't do that. I have read in the CAESAR II help if the case is like this the we must make the vessel nozzle perpendicular to the nozzle centre line? how come this can be achived?

Thanks

Hi,
You have to read WRC 107/297 for that.

Even when you have a top nozzle on head of a column etc, calculations are performed by converting ellipsoidal head to equivalent sphere and considering nozzle as radial to sphere.
This is the option/general practice followed.

C2 just implements WRC 107/297 that and make our job easier.

Hi too stressguy,
In which part have mentioned it???
If you follow WRC107 rules in CAESAR II modelling the nozzle vector should pointed to vessel centerline axes, in this case (vertical nozzle on vessel head) should be modeled as horizontal modeled???? how can you do that?
For me its more safer to use FEA software to get the flexibility and SIF and input it back to CAESAR II.
COADE has write this in their mechanical Engineering News August 1992.
So Richard or Dave, what is your comment?

Hi again,



My earlier answer was to this question, which I have represented in "CASE I" of the attached pdf.
"CASE I" is an approximate method of doing, when roof nozzle centre line and column centre line matches.


Even in Case I, the calculation will be approximate and one of coade write up explain this methodlogy. Im not aware if C2 does it automatically, but you can always convert it into equivalent sphere.



FEA is obviously a better choice.




Do refer WRC 107/297, C2 is just a tool.


Experts opinion are welcome.

Ok, then you mean by considered it as spherical as in WRC 107 then the Vessel centerline can be assumed as in X or z direction, meanwhile nozzle still in Y direction.
Thanks, for the explanation, but still using FEA is the best way in our opinion in this case. Btw i agree with you CAESAR II is only Tool.
Thank you very much.

Maybe Richard can little bit explain the words in the help facilty :

Meanwhile in one of the CAESAR II Topic for the almost the same topic Richard Ay said that:

I think what Stressguy81 mentioned is WRC 107, and Ricahrd answer for that is for WRC 297, so it is clear now that the intrepretation for CAESAR II help facilty Quote above is for WRC 107 we can considered the vertical vessel as spherical as in Case 1 that stressguy81 give and as in WRC 107, so that the cosie directional can be orthogonal, but for WRC 297 i think it can't be applied since it only for Cylinder-cylinder intersections, so for this case there is to option:
1. Considered itas spherical and do the WRC 107 analysis in CAESAR II.
2. Or you can use FE Pipe to get the flexibility and input it back to CAESAR II.
Thanks.

3. Another methosd to analyze this case in CAESAR II is by using PD5500 nozzle modelling.

Still the easy and accurate for this case from three above method is the second method.
Thanks

Dear Nalibsyah,

I think for head or bottom vessel nozzle, method ass stressguy81 mentioned can't be applied both for WRC 107 and WRC 297. There has been several same question about this if you use the search button....(i'm sorry i don't understand how the way to refer the thread to you :)).
So i thin for this Head or Bottom vessel nozzle, better to use FEA software to get the flexibility and you can input it back to CAESAR II or you can use PD5500 nozzle modelling as you mentioned above in your method 2 and 3....(but for quotion PD 5500 will give you very conservative result, it is better you to read and undertand it first).
Meanwhile for hillside nozzle as Case 3 in stress guy attachment, you can still modelling it in CAESAR II and insert WRC 297 flexibilities.

Thanks

Tengku Syahdilan

Hi Tengku and Nalibsyah,

The earlier attached pdf was for WRC 107 only
Read these threads
http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=36983#Post36983
http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=6960#Post6960

Some links that might interest you.
http://www.ijame.uz.zgora.pl/ijame_files/archives/v11PDF/n4/965-979_Article_19.pdf

On the estimation of stress concentration and flexibility at nozzles in ellipsoidal vessel heads

ok thank you very much stressguy and Tengku.