I modeled a universal expansion joint within a pipeline following the Application Guide.

Node 10-20: rigid, half of the total weight
Node 20-30: expansion joint, with trans/bending/axial stiffness and effective ID blocks filled.
Node 20-40: rigid, zero weight; Restraints at Node 40 Cnoded to 30: RY, RZ, X
Node 40-50: rigid, half of the total weight

After running, the restraints summary are as follows:

40 Rigid RY Rigid RZ Rigid X
3 OPE ********* 0. 0. 0. 27833. -35264.
4 SUS 6. 0. 0. 0. -2172. 5478.
5 EXP ********* 0. 0. 0. 30005. -40742.

Is this Fx the pressure thrust force? Why they are ********* ?

Be sure you don't have temperature on your tie rod element 20-40. That could cause a rather large axial force that would show up as stars. If setting that element to ambient (be sure to change the following element back to operating temperature) doesn't fix the problem send your model to techsupport@coade.com and we will take a look.

Loren, how C II will take that portion ( Node 20-40 ) as a pipe, since he has specified that as Rigid element with Zero Weight. If he has speficied that as pipe only the parameters will come in to picture.

No, rigid elements (even zero-weight rigids) do expand thermally. We use these to represent vessel radii that are expanding thermally and therefore applying a thermal load to a nozzle connection.