Hi @GuillermoAQ ,
Unfortunately, there does not appear to be a way to do this. Structure labels within the data option would need to have the component capability of Text for Each (referring to each pipe connected to the structure), the option is not available for this.
For pipes, we do have the ability to extract the Pipe Start/End Direction in plan, but this returns an angle and not a cardinal direction letter.
If it's something you need, I would post this onto the Civil 3D Idea Station to help gain community support for providing the additional labeling functionality we can use on typical structure labels.
https://forums.autodesk.com/t5/civil-3d-ideas/idb-p/31