Preserve Edges
Use the Preserve Edges tool to ensure that specific component edges and feature lines do not accidentally get discarded during auto cleanup or batch meshing.
Note: FE geometry is not supported for this
                tool.
        - 
                From the Topology ribbon, click the Preserve Edges tool.
                
Figure 1. 
 - Select edges.
 - Select whether they should be preserved or unpreserved from the guide bar.
 - 
                Click 
.
                Preserved edges are highlighted.