Dear Experts,
I am working with vessel i nter connection piping system, line design temperature is 121 0C and line size is 20 inch, we have done the detailed stress analysis and the nozzle junction is considered anchor with Cnode option, the piping load on the equipment nozzle is higher than the allowable. Here the pipe routing changes is not possible since it is process requirement, However we have performed the nozzle pro analysis (FEA) for excessive nozzle loads and found the stress are not with in the allowable limit.
Also we have attached the snap shot for the failure nozzle.

In FEA analysis we found the following stiffness data.

1. Axial Translational Stiffness = 631487. N /mm.
2. Inplane Rotational Stiffness = 4212978432. mm. N /deg
3. Outplane Rotational Stiffness = 1448742400. mm. N /deg
4. Torsional Rotational Stiffness = 236483166208. mm. N /deg

Kindly advise how we can correlate these stiffness in CAESAR II model to reduce the piping load on the equipment nozzle.

Insted of connecting nozzle to vessel through anchor c-node, you can individually define X, Y, Z, RX, RY, RZ at nozzle with same c-node of vessel.

Ensure consistency with respect to axis and units while entering the stiffness data in Caesar-II

Thank you for immediate reply,
We need some clarification how to comply these stiffness on vessel nozzle junction (cylindrical nozzle on Spherical vessel), here my nozzle axis is X-Direction, so Axial Translational Stiffness X= 631487. N/mm. And other two (Y & Z) direction stiffness are not required. If required please advice.
How to take the rotational stiffness for Rx, RY & Rz
The Torsional Rotational Stiffness for Rx = 236483166208. mm. N /deg, kindly advise for the other two rotational stiffness also. How to considered the Inplane & outplane Rotational Stiffness.

Hello Venket

I cannot see all the axes in your snap.
Assuming that Vessel Lateral Direction is Y Axes,

You can leave Y & Z Stiffness blank as CAESAR II will take the default value for them and you are correct about RX = Torsional Rotational Stiffness.
Now,
In plane and out plane rotational stiffness should be
RY = 4212978432. mm. N /deg [Inplane rotational Stiffness]
RZ = 1448742400. mm. N /deg [Outplane rotational Stiffness]
I think the attached image can help you in this regard if i am wrong.

Have a good day !!

If the software does not provide a stiffness value in the anticipated direction, the assumption is to use maximum resistance. Thermal expansion of the unit attaching the two vessel sections does not occur without resistance.

In-plane and out-plane does not make sense to me in this scenario as the CL of the nozzle is parallel to the CL of the vessel section. As Lukachiri demonstrates, it only makes sense when the two vectors are non-parallel, and preferably perpendicular.

You'll need to review your software documentation to be certain, but noting that one value is 4x the resistance of the other direction, you can intuit that it's easier to twist the nozzle in the horizontal plane rather than the vertical plane due to its proximity to the edge of the vessel.