As Michael mentioned, there are flange checks and other things you can use to see if the flange is overloaded.

In general, the piping specification you're designing to should be adequate for the flanges allowed in that spec (meaning piping flange pairs). Other flanged connections, such as tank/equipment nozzles, should be evaluated and ensure they don't exceed their allowable loads.

But rigid elements in Caesar do not have allowable stresses. They still experience thermal growth/contraction, which makes them ideal for representing valves or centerlines of equipment connected to your piping.