Hi Dave and Rick,

I need to confirm my understanding and hope to be corrected on the above subject. In modeling a piping system connected to a nozzle were the nozzle itself is displacing in three direction say -Y,+Z & +X due to thermal expansion. Since I need to start the model at this nozzle, the conecting node should contain D1 and D2 & D3
(D1 for -Y, D2 for +Z and D3 for +X). So that my operating case (W+P1+T1+D1+H, where aplicable) will show three lines, one with D1 and another with D2 and another with D3. I would evaluate D1, D2 and D3 and by the way for one operating temperature only,these displacements dx, dy and dz should all be under vector 1 right? If dy happened to be a displacement at temperature 2, then it should be in dy under vector2. And this is how I was told: no matter dx,dy and dz are in one or two state of temperature, they are going to be evaluated separately in the load cases. So, what I mean is what happened to the model I saw and realize that even they have three displacements in one temperature as shown on connecting node at spreadsheets there were no D2 and D3. I saw that D3 sometimes has a much bigger value than D1 and I thought it is much more important to evaluate it by showing it in the load case combination.

It sounds like your nozzle displaces in all three directions for each operating temperture. Then for each temperature you need to define a displacement vector, with values for one or more degrees of freedom. For example:
<table>
<tr><th>Item</th><th>Vector 1</th><th>Vector 2</th><th>Vector 3</th></tr>
<tr><td>Temp.</td><td>T1</td><td>T2</td><td>T3</td></tr>
<tr><td>DX</td><td>dx1</td><td>dx2</td><td>dx3</td></tr>
<tr><td>DY</td><td>dy1</td><td>dy2</td><td>dy3</td></tr>
<tr><td>DZ</td><td>dz1</td><td>dz2</td><td>dz3</td></tr>
</table>

Then in your load cases, you would pair D1 with T1, D2 with T2, and D3 with T3, where "D1" represents "dx1", "dy1", and "dz1".

Rick,

The nozzle displaced in three directions but in only one operating temperature. It involves three direction during expansion because of its location with respect to centerline and anchor location of vessel it is attached to. So my point is that if you are giving dy, dx and dz under T1 in your diplacement entry window ( say rx, ry and rz is rigid) then how come their load case contains only one line having D1. I don't know if it is right. I thought that having these three displacements you would necesarily create load cases in three lines for operating say:
W+P1+T1+D1+H (say WITH HGR) OPE
W+P1+T1+D2+H OPE
W+P1+T1+D3+H OPE
When I saw their load cases without D2 and D3 at all in any line, does it make no difference? Did they do it becuase the displacenments occured at only operating temperature? If it so why then do you neeed to plug in displacement on the other two direction? So, are they right? Thanks.

It depends on their input. If the displacements are setup the way I described above, then the load cases are correct. If on the other hand the displacements were defined in the input as:
<table>
<tr><th>Item</th><th>Vector 1</th><th>Vector 2</th><th>Vector 3</th></tr>
<tr><td>Temp.</td><td>T1</td><td>T1</td><td>T1</td></tr>
<tr><td>DX</td><td>dx1</td><td>0</td><td>0</td></tr>
<tr><td>DY</td><td>0</td><td>dy1</td><td>0</td></tr>
<tr><td>DZ</td><td>0</td><td>0</td><td>dz1</td></tr>
</table>
then no the load cases are not correct.

The input should really be defined as I posted above (in the earlier posting). Vector 1 should represent the displaced state of the nozzle (all 6 dofs) for condition 1, Vector 2 should represent the displaced state of the nozzle (all 6 dofs) for condition 2, and so on.

Gimini55,

"no matter dx,dy and dz are in one or two state of temperature, they are going to be evaluated separately in the load cases. "

This is false. dx, dy, and dz are just an arbitrary coordinate system that we create so that we can evaluate positions and movements in a 3D world.

In reality, your nozzle displaces in one direction from point "A" at your install temperature to point "B" at your operating temperature. We identify that displacent with a vector containing three components, a dX, dY, and dZ. These three components together give you your total D1 that you use for your load case.

Hit the reply a little too fast.

One other thing. Your dx, dy, and dz that give you D1 are based on expansion from your install temperature up to T1. If you have a T2 to evaluate, your are going to have a D2 displacement made of of different dx, dy, and dz components.

Thanks Rick and thanks a lot for clarification Mr. Klein. I could quickly grasp yur explanation. I thank you so much.

Regards,