An issue with that much thermal expansion is that the actual piping system (especially around the loop) won't behave in the field as it does in the Caesar simulation. You will get bigger friction imbalances than Caesar is likely to generate and could therefore get much higher stresses around the loop.

Also, long straight runs are normally a bigger concern with regard to slugging (compared with having additional loops) as it often takes a certain length of straight run before the wave of liquid reaches the top of the pipe.