Pie Gauge is a disk of highly permeable material divided into eight sections by non-ferromagnetic material. The joining of sections act as artificial defects that radiate out in different directions from the center which allow the inspector to ensure magnetic fields are properly oriented for the inspection at hand.
The sections are furnace brazed and copper plated. The advantage of the pie gauge is that it is easy to use and it can be used indefinitely without deterioration.
Manufactured per ASTM E709 & E1444 standards