while we are giving displacements/thermal movements at equipment connection is it correct that we are considering RX,RY,RZ are zero's?, if yes why?

Because the nozzle is fixed in all 6 degrees of freedom. If you leave any "pre-defined" displacement field blank, CAESAR II assumes that DOF is free. This is not the case with a nozzle.

if that is the case, if we model the nozzles along with drum as a equipment like equipment modelling in caesar technical reference manual,
there will be some values we are getting for rx, ry rz right?
can you explain, please?

If the pipe connects to a nozzle, all six degrees of freedom are fixed. If we assume there is no thermal growth of the equipment, the nozzle displacements and rotations will be zero. Therefore, for the pipe that terminates at this nozzle, you would specify an "anchor restraint".

Alternatively, if this same nozzle experienced movement due to the thermal growth of the equipment, then those displacments should be specified as the boundary condition. If we assume this growth is "dx=0.3" and "dy=0.2", then the proper displacment specification would be:
dx=0.3, dy=02., dz=0., rx=0., ry=0., rz=0.

Omitting the specification of the zero values for the rotations would mean those degrees of freedom are free to rotate (which isn't the case). If there was any tendancy for the pipe to rotate, the resulting displacement report would show rotations at this nozzle, instead of zero values.

was it same for the flanged nozzle and welded nozzle

Why should that have any influence ?????

you are not getting my point clearl which was that rx ry rz's are zero for flanged nozzle or for welded nozzle or for both or for any particular one? can you explain?please

If you leave RX blank, you imply that the node provides no restraint against rotation about the X axis - it is free to rotate; no stiffness.

If you set RX to zero, you imply that, no matter how much bending is supplied by the piping system, that node will not be able to rotate about the X axis - it is fixed in rotation; it had infinite stiffness (in CAESAR II that's about 1E12 lbf/in).

We're talking about imposed displacement but the focus is on stiffness - the stiffness of the nozzle/shell connection, not the flange face or weld end of the nozzle. Of course that stiffness need not be only zero or infinite.

but when i analysed main steam line with rx,ry, rz's are keeping blank it was passed,
but with rx, ry,rz keeping zeroes it was failed, why?which was correct?
can you explain?please

You need help from someone in your company who knows about stress analysis.

dear moverz,
first try to understand someones problem rather than throwing words, it may hurt sensitive people, please.

Both Rich Ay and Dave Diehl have explained all there is to know about defined (a number or 0 in a field)and free (no number) end displacements and rotations. You have asked many trivial questions and it is now for you to understand.

Keeping blank you are allowing it to freely rotate. thats not correct. irrespective of the connections flanged or welded to the equipment nozzle, always Keep Rx,Ry,Rz Zero meaning u r not allowing it to rotate, thats what done in actuals

Rubbish.

The facility in Caesar to define displacements and rotations is not limited to nozzles.

There are many circumstances where you might need to include specified translations at a point whilst allowing free rotations.

The reply of keeping zero for Rx/Ry/Rz thereby not allowing to freely rotate is for the specific query raised above for pipe connecting to the equipment NOZZLE....