IRIS — Internal rotary inspection system

IRIS is a new ultrasonic system for inspecting air‐cooled heat exchangers. It employs the conventional pulse echo technique for measuring the wall thickness, but uses a novel method for displaying the measurements. All of the measurements made during a complete scan, around the circumference of the tube, are displayed on an oscilloscope screen to produce a stationary, rectilinear picture of the circumferential cross section. Missed and false measurements are easily recognised and can be compensated for by extrapolation of the valid measurements. The novel display allows wall thicknesses to be measured, virtually down to zero in ideal circumstances.