Those dimension tools need 2D geometry to work. Notice that the tool requires an arc or circle. In my screen shot the upper pipe was created by extruding two concentric circles, these circles were then dimensioned. The lower pipe was made using the "Pipe" tool. That was dimensioned using the "Vertical Dimension" tool. and snapping to the quadrant points. Just add a circle to your pipe and dimension that or use the Vertical/Horizontal Dimension tools.