Ultrasonic characterisation of microstructures damaged by high temperature hydrogen attack

Nageswaran, Channa; TWI Ltd.; United Kingdom

Nageswaran, C.; TWI Ltd; United Kingdom

ID: ECNDT-0471-2018
Session: PAUT & TFM 1
Room: G2
Date: 2018-06-11
Time: 13:50 - 14:10

High temperature hydrogen attack (HTHA) of carbon and low alloy steels is a critical problem in the refinery industries. A number of techniques have been used in the past to detect and characterise the existence of this in-service damage mechanism using conventional ultrasonic instrumentation. Their capability to detect the initial emergence of damage is currently under review in industry and the availability of advanced array probe imaging techniques potentially offer enhanced capabilities. This paper will consider the issues surrounding early-stage detection of HTHA in susceptible steels, assess the capabilities of established conventional techniques and explore potential advantages of using array ultrasonic imaging techniques. Evidence from theoretical simulations of the inspection scenario as well as data collected on a specimen containing HTHA damage will be presented.