Are your Civil 3D pipes not smooth in your section views?
Do they look more like diamonds then pipes?
Here is a little gem that will smooth out this problem.
The smoothness of the pipes in the section view is created using the Civil 3D variable Facetdev (Facet Deviations) which is set at the drawing level at 0.5 as the default.
This variable controls the curvature smoothness of the pipes in section by defining the amount of segments used to create the curves. This means the more segments that make up the pipe edge, the smoother the curve. The lower the number is set, the more segments are used to draw the pipe, because this number represents the maximum distance from the middle of the segment (chord) to the arc defined by the pipe size.
The maximum segments a curve can have is controlled by the Civil 3D variable Facetmax, which can be set from 100 to 10,000.
Set Facetdev by entering the variable name at the command line and typing a smaller number. Adjust this number until you are satisfied with the result. Keep in mind a setting Facetres lowere and Facetmax higher will effect Civil 3D performance.
A good idea is to set these variables in your template drawings, or even make them part of an acaddoc.lsp file. (see previous tip on acad.lsp & acaddoc.lsp)