Investigations were conducted regarding the use of the ultrasonic pulse echo and the infrared thermography nondestructive evaluation (NDE) methods for detecting voids and delaminations in adhesive-bonded seams of single-ply roofing membranes. Previous studies had indicated that these defects could be detected using the two NDE methods. In the present study, voids incorporated in 1.2 m (48 in.) long seam test specimens were located by the pulse-echo method using a wheel transducer to scan along the length of the seam. These results indicated that the ultrasonic pulse echo method using a wheel transducer can be useful as a field technique for assisting in the quality assessment of seams. When using the infrared thermography method to evaluate the seam specimens, it was found that, unlike previous studies, only sections of some voids were detected and that other voids were not detected at all. It was suggested that collapse of the voids due to the applied pressure during seam formation might have provided insufficient surface temperature differential between the bonded areas of the seam and the void areas of the seams during transient heat flow. The results raised concerns that the infrared thermography method may not be practical for the general detection of voids of seams in service.

Date Published: 11 May 1987
PDF: 9 pages
Proc. SPIE 0780, Thermosense IX: Thermal Infrared Sensing for Diagnostics and Control, (11 May 1987); doi: 10.1117/12.940485

Published in SPIE Proceedings Vol. 0780:
Thermosense IX: Thermal Infrared Sensing for Diagnostics and Control
Robert P. Madding, Editor(s)