The pipe has the parameter "Outer Diameter", "Elevation".
As for the "Elevation", this is the center level of the pipe. (Fig. 01)
In the IFC Data Mapping, the "Elevation" could be mapped. (Fig. 02)
In the Label, how to show the bottom level?(Fig. 03) The bottom level is calculated as below
BL = CL - Diameter /2
where BL = Bottom Level
CL = Center Level