The campus where I work has a long covered walkway (~.5 mile) which has several labeled pipes running under the roof (chilled water, fuel oil, air...). All of the pipes run dead straight except for the natural gas lines, which have little loops spaced about every 250ft, as seen in the attached image (the lowermost, yellow line. There's another natural gas line hidden above all the others, which also does the same thing.)
The line isn't branching at these points, and there doesn't seem to be any need to divert the pipe in order to support it. I've looked at some building codes to see if I could find a reason (or even a requirement) to insert these.
Any ideas as to what these are? It's driving me batty!