Revit 2013 introduces a new Arrow Style for Loops, though it may not be immediately obvious how to use it in an upgraded project.
- On the Manage tab > Settings panel > Additional Settings > select Arrowheads
- Select any of the types, and click Duplicate...
- Name the duplicate Loop, or something suitable, and then click OK twice.
- Now, select a tag with a leader in a view (such as the Pipe Size Tag).
- On the Properties Palette, click Edit Type.
- Click Duplicate...
- Name the new type 'Pipe Size Tag with Loop', and click OK.
- Set the Leader Arrowhead to Loop (or whatever you named it in step 3.)
- Click OK.
Your pipe tag now has a loop leader.