Phased array inspection at elevated temperatures: effects of ultrasonic beam skew

摘要

The design of a phased array system is described for the inspection of test-pieces such as pipe welds at elevated temperatures of up to 350℃. Wedges are built from plastics resistant to high-temperature degradation and equipped with a cooling jacket around the phased arrays. A model of the beam skew pattern due to thermal gradients inside a wedge is developed. The model demonstrates how the path of an ultrasonic wave will curve according to its alignment with the direction of the temperature gradient. The results may be used to modify an ultrasonic inspection plan to partially compensate for the effects of elevated temperatures.