Time of Flight Diffraction (TOFD) uses diffracted ultrasonic signals from defect tips for precise weld flaw detection, sizing in pipelines, vessels, tanks. Tove Leeds positions transmitter-receiver pairs across welds, measuring time-of-flight for depth/height accuracy to 0.1mm.

Replaces radiography in oil & gas girth welds, power boiler headers; excels thick sections (12-200mm), vertical cracks. Insensitive to orientation unlike pulse-echo.

Combines with PAUT; ASNT-certified techs calibrate per BS 7706/ISO, produce B-scans, reports for fitness-for-service, growth monitoring.