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Six cracked A36 steel gusset plates that formed part of the roof trusses of a large manufacturing facility were discovered during a routine final inspection of a new building construction. Two different-size plates from different locations in the building were removed and tested. It was determined that the gusset plates failed in the heat-affected zone via an intergranular microcracking mode due to hydrogen-assisted underbead and toe-weld cracking. Proper nondestructive testing techniques for magnetic particle and radiographic inspection of the plate-weld gusset areas were recommended.

This paper describes the investigation of a corrosion failure of bottom plates on an aboveground tank used for the storage of potable water. The tank was internally inspected for the first time after six years of service. Paint blisters and rust spots were observed on the bottom plates and first to third course shell plates. Sand blasting and repainting of the bottom plates and first course shell plates was to be used as a remedial measure. However, during the sand blasting, holes and deep pitting were observed on the bottom plates. On-site visual inspection, magnetic flux leakage (MFL) inspection, ultrasonic testing (UT), and evaluation of the external cathodic protection (CP) system were used in the failure analysis. The corrosion products were analyzed using energy-dispersive X-ray analysis (EDAX). The failure is attributed to the ingress of water and its impoundment under the tank bottom along the periphery inside the ring wall and failure of water side epoxy coating. Various measures to prevent such failures in the future are recommended.