I am trying to run FEA on an adapter assembly but I am having issues with fixing the end conditions.  The Stress is high since it is trying to hold a pipe that needs to expand.  These end conditions have to be fixed/fixed guided in order to determine the correct results.  Anyone have an answer?

Boundary conditions:

Adapter material: 4140 steel

Ambient Temperature: 68 degrees F

Thermal load: 500 degrees F

Fixtures analysis 1: Fixed, Guided sliding connection with x and z axle restrained.

Pipe wall thickness: .38”

Pipe ID: 1.25

Results required: Displacement, safety factor and resultant forces.