Does anyone have advice for modeling piping that "rolls" over hills without fittings over long distances? I have been told that this is called "roping" pipe over the topography of the land.

The piping will be properly supported to stay within code deflection limitations. But over large horizontal distances, the piping will actually be rising or falling gradually (bending). Would this affect stress/loads in any way? Or can an assumption be made that the pipe bend angle is so small (over the large distance) that the small bend is negligible?

If this cannot be ignored, then this seems to be more of a modeling issue that I am not capable of at this time. Maybe someone has come across a COADE/Intergraph document that explains something like this?