Fatigue Crack Monitoring from Initiation to Through Cracking in Welded Thick Steel Sections

This report describes the overall Non-Destructive Evaluation (NDE) policy of the Fatigue Section, ARE Dunfermline, with respect to the fatigue testing of internally stiffened welded steel structures. These structures, of thick section high yield strength steels, are subjected to high external cyclic pressures in a water environment. The report covers the application of various non-destructive testing (NDT) techniques (Visual, MPI, Eddy Current, ACPD, Ultrasonic ToFD and conventional Pulse-Echo Ultrasonics) in the areas of weld assessment, fatigue crack initiation detection, fatigue crack sizing and fatigue crack growth monitoring. Data is presented on the size of initiating cracks expected to be detected and on the accuracy of the sizing and monitoring techniques used. Keywords: NDT, NDE, Visual, Eddy current, ACPD, Ultrasonics, Time of flight diffraction, ToFD, Crack initiation, Crack sizing, Growth rate, Great Britain, Welded steel structures.