Topographical Evaluation of Subsea Defects in Offshore Structures Using a Shadow Moire´ Technique

Optical techniques based on the moire´ phenomenon are powerful tools with applications over a range of engineering inspection/measurement problems. A study of the application of the shadow moire´ method in connection with detailed examination of replicas taken from damaged subsea zones of offshore structures has been performed. Measurements of the surface profiles of areas altered by processes such as corrosion pitting, and remedial grinding of cracks, were obtained using the technique. This method offers a convenient “real-time” approach to visualizing height contours.