Underwater Nondestructive Testing Equipment and Techniques,

Aimed at producing hardware for ship hull inspections, this project focused on stereophotography, ultrasonic thickness gaging and flaw detection, and magnetic particle inspections. In each case, hardware was chosen on the basis of an extensive survey of users and manufacturers both in America and Europe. Modification and adaptation of off-the-shelf equipment was performed at NCSC in order to arrive at systems easily used by U.S. Navy divers, and tests were run to determine the performance of each system under laboratory and field conditions. The stereophotography system described is an inexpensive unit which produced photogrphs of excellent quality in spite of zero visibility conditions. Corrosion pit depths or fouling heights can be measured to approximately or - 164 inch, and incipient paint blistering can be detected before the blisters pop. The ultrasonic equipment described provides audible feedback to the diver to assist him in positioning the transducer. Also, thickness readings and flaw signal amplitudes can be stored on computer tape. The magnetic particle inspection systems include permanent record techniques such as magnetic rubber and transferring magnetic particles to a variety of putty-like materials.