let me find that post where we discussed that mal-function here
FACETDEV
The following sections describe best practices for displaying pipe networks in profile and section views.
Pipe Appearance in Section View
Pipe sections are drawn using the FACETDEV (Facet Deviation) system variable. This variable controls the smoothness (tessellation) of curved edges of the pipes in section view.
The default value of FACETDEV will usually cause pipe sections to be displayed in section views with line segments, rather than as smooth curves. The following illustration shows an elliptical culvert in section view when FACETDEV is set to 0.5 feet.
If you set FACETDEV lower, to 0.01 for example, the appearance of the pipe sections will become more circular, as shown in the following illustration.
The number you specify for facet deviation defines the maximum distance from the chord to the arc—the chord being an edge that is created from faceting the curve to the true mathematical arc. The facet deviation has a range of greater than zero (0) and no upper limit. The lower this variable is set, the more segments will be used to draw the pipe. The minimum number of segments is 8.
NoteThe maximum number of facets is controlled by the FACETMAX variable. This variable can be set from 100 to 10,000. Note that using a small value for FACETDEV and a large value for FACETMAX will adversely affect drawing performance.
NoteFACETDEV and FACETMAX are AutoCAD Civil 3D variables (rather than AutoCAD variables). They are therefore not listed when using the AutoCAD command SETVAR.
