This test is used to evaluate the quality of insulation and its ability to withstand wrinkling. Wrinkles can occur to insulation when bent back and forth frequently, eventually causing the insulation to deteriorate.
The particular concern here is on tape wrapped insulations. During the fabrication process, an adhesive is used to hold the tape wrap layers together. If this adhesive is not prepared right in formulation or application, the tape wrap layers may separate during mechanical stressing. This layer separation can be often identified visually with the presence of wrinkles.