Nondestructive detection and assessment of high temperature hydrogen attack damage in carbon steel pressure vessels

A nondestructive testing approach capable of evaluating high temperature hydrogen attack (HTHA) damage in carbon steel pressure vessels is presented. The approach, involving non-collinear wave mixing of ultrasonic waves, is applied to a test sample extracted from a retired pressure vessel. Nonlinear ultrasonic results are consistent with tensile test results obtained using specimens extracted throughout the thickness of the pressure vessel, and with damage observed using scanning electron microscopy micrographs. Results show that the nonlinear ultrasonic approach has the potential of being capable to detect and assess HTHA damage through the thickness of pressure vessels. The method only requires access to the vessels’ outside surface, which makes it very attractive for field inspections.