The internal rotary inspection system (IRIS) probes are well suited for petrochemical and balance-of-plant (BOP) tube inspections. They use an ultrasonic beam to scan the internal surface of the tube in helicoidal patterns, ensuring that the full length of the tube is tested. The IRIS probes operate in pulse-echo mode to measure wall thickness, material loss, and defect orientation within the range of 0.5 in. to 3 in. ID.