'blisters' which may eventually generate enough pressure to rupture the metal
Hydrogen blistering usually occurs in ‘sour’ systems (oil or gas containing large amounts of hydrogen sulphide) at high temperature when hydrogen atoms diffuse into the steel, hydrogen molecules then form at internal defects or inclusions, (usually small delaminations) over time this can form voids or ‘blisters’ which may eventually generate enough pressure to rupture the metal. Such hydrogen induced blister cracking has been observed in steels, aluminium alloys, titanium alloys and nuclear structural materials. Phased Array NDT Inspection is one method used to detect these voids.
This application note demostrates how the Veo phased array ultrasonic flaw detector can be used for inspection of Hydrogen Blistering in Steel.
The veo was used with a T5-5.0M64E0.8P DAAH Probe with 1-inch flat delay line (T5-25.4WOD) and cable.
The default settings were used as a starting point and the gain and path length adjusted so that the back wall echo from the ‘good’ section was clearly visible.
To download the complete file and specification information click here.