This test method is useful for measuring the wall thickness of plastic vessels and other plastic structures where the geometry of the equipment does not permit direct measurement by conventional methods, such as micrometers, calipers, and rulers. This test method is not limited to plastics and can be used for all nonmagnetic materials. It provides for a rapid and accurate thickness measurement, without the need for drilling and repair of holes.

Accuracies are not affected by density variations, permitting the measurement of composites made up of a variety of materials of varying densities. By placement of the magnetic source on the mold surface, thickness measurements can be made during and after fabrication of plastic products to verify thickness and adherence to specifications.