Good question. I can see the confusion between the drawing symbol and visual appearance. The drawing shows the arrow starts from the centerline to a distance three times the radius. There is a break in that arrow with the text "Ds is from Table 11 for".
The other source of confusion is that in the schematic, the measurement location is shown at a distance that appears to be at 3 times the radius from the outer edge of the nugget.
I would interpret the drawing as measuring from the center of the nugget out a distance of 3 times the radius.
Girish
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