The typical operating cycles of coke drums create thermal stresses that eventually lead to fatigue cracks called ‘elephant skin’ (ES) in both the inside diameter (ID) and outside diameter (OD) of coke drums. Traditionally, these have been inspected through a multi-stage process from initial dye penetrant inspection, visual assessment of ES crack depth, baseline ultrasonic thickness (UT) gauging, exploratory grinding to chase crack tip/s of select locations, confirmatory dye penetrant inspection, and UT gauging to determine the remaining wall thickness, to calculate the crack depth. This traditional process is not only slow and a time-consuming chain of activities, but also leads to subjectivity in the crack depth assessment, and a challenge to coordinate different groups in a turn-around. An Eddy Current Array (ECA) inspection crawler was designed and built to solve these issues.

Subject
Electric current, Field performance, Test methods, Materials, Probes, Nickel based alloys, Grinding, Inspection, Density, Crack depth, Coke, Visual assessment, Cracks
Keywords:
coke drum inspection, elephant skin (ES), eddy current array (ECA), crack inspection, weld inspection
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2024
Association for Materials Protection and Performance (AMPP)
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