Tank base cycles with the level of the fluid in the large ground supported tanks. Tank base moves between maximum and minimum settlement values depending on the design of the civil work under the tank. In some cases you can provide thick concrete slab for relatively small tanks, so there could be insignificant settlement in case the piping is on the same slab. Most cases in large plants you may see the pipe rack sattlement is differently than the tank settlement since their civil work are different.

You need to see all the loads on the piping as well as the settlement cycles if available.
The same can be said for the thermal loads. The thermal loads are cyclic since you cannot maintain any equipment on the exact temperature, there are ups and downs within control limits. But we use the minimum and maximum to consider in the analyses.

So, we are the designer to consider all the load requirement. Both thermal and settlement cycles will interract which will be the worst case. Thus we consider both in the same analysis under the same load case to simplify the analysis.

I trust this answer your question.