Hydrogen Blister Progression FMC/TFM Assessment
Hydrogen blistering usually occurs in systems where oil & gas contain large amounts of hydrogen sulphide. At high temperatures, when hydrogen atoms diffuse into the steel, hydrogen molecules form an internal defect or inclusion that usually migrate to become a small delamination. Over time, this can form voids or blisters which lower the equipment MAWP (maximum allowable working pressure) and may lead to equipment failure.
Phased array significantly improves the detection and evaluation of that type of damages. The 2D encoding capacity of the Veo+ helps the user to quickly scan a significant area of the part and rapidly analyse these defects. However, blistering is an evolutive problem and it is a challenge to evaluate its progression through time. The dispersion of the phased array beams makes it difficult to determine the size using the dimensional approach while the amplitude sizing technique is highly sensitive to the acquisition conditions and inspection technicians' practices.
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