As a follow up to a previous BLOG “Civil 3D Labels: Controlling Pipe Leaders in a Dragged State”, the goal here is to have the label sit ABOVE the pipe and have the arrow point to the CENTER of the pipe.
The created Leaders when dragged will by default go to the Anchor Point location. As shown in a previous blog and seen below: Above, Center, or Below:
The goal here is a “dual” label, that sits above the pipe and points to the center. For its configuration, the Anchor Point is set to Centerline and the TEXT Attachment is set to Bottom center: This will cause the label run through the pipe. 
To shift the location of the label, an expression will be used to slide the text up on the Y axis. The Expression created here “Pipe Dia” reads the pipe diameter and scaled by drawing scale:
(({Pipe Outer Diameter or Width}*0.5)/{Drawing Scale Conversion})+(.01/{Drawing Scale Conversion})
NOTE:
Depending on where the default position of the text (above, centered or below), the expression can be created to yield a whole/half or positive/negative value.
Here the expression is applied to the Y Offset field, the label will shift up out above the pipe in the default location and the arrow to point to the center of the pipe. 
This is one of our many posts on leveraging Expressions to shift and space out labels. IMAGINIiT can help you set up and configure Civil 3D.
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