Come on, think a little. What you have is an expansion loop. This is an offset portion of the piping that is parallel to the main run.

1. The offset (as well as the perpendicular legs) expands as temperature increases, too.

2. The expansion of the two legs of the main run expands and forces the inner elbows on the two perpendicular legs toward each other.

3. The expansion of the portion of the expansion loop that is parallel to the main run expands and forces the two outer elbows on the perpendicular legs away from each other.

4. There is a stiffness associated with each elbow, and with all of the 5 legs of straight pipe.

WHAT DO YOU THINK THE RESULT OF ALL THIS IS?

A: The expansion loop produces bending moments in all associated components. (How do you think the bending stresses are generated? Did you think you could have bending STRESSES without bending STRAINS?) And the bending moments impose a radius of curvature on each straight leg of pipe. You can verify this for yourself if you compare the lateral deflections of the two outer elbows to the lateral displacement of the midpoint of the parallel leg of the expansion loop, if you have placed a midpoint node.