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Internal Rotary Inspection System (IRIS) 3000/9000

The IRIS system operated by Torch Integrated Inspection Services is the latest in microprocessor based equipment for the ultrasonic testing of heat exchanger tubing.


IRIS is based on immersion pulse echo ultrasonic principles. The test head consists of a high frequency, high resolution transducer, mounted longitudinally to the tube axis, and a 45o mirror mounted on a water driven turbine. The test head fits centrally into the flooded heat exchanger tube. Ultrasonic pulses from the transducer, emitted parallel to the tube axis, are reflected by the mirror and strike the tube inside wall at normal incidence. Some of the ultrasound will be reflected from the inside wall back to the transducer and some will pass into the tube material. When the ultrasound within the tube material strikes the outside wall, again a part of the energy will be reflected back to the transducer. The time delay between the echoes from the inside wall and the outside wall of the tube is an indication of the tube wall thickness. As the turbine rotates, the ultrasonic beam covers the full circumference of the tube and by slowly withdrawing the test head 100% of the tube can be inspected.


Due to the digital nature of IRIS, the accuracy of calibration and standard of presentation are of the highest level. The unique feature of the IRIS is the method of display. The vertical axis of the image represents 0 – 360 degrees around the tube circumference and the horizontal axis represents the tube wall thickness. In effect, the image is an expanded cross section of the tube at any given position along its length.

Site Implementation

The equipment operates on 110 volts AC mains power. A fresh water supply at 40psi (2.7 bar) or greater is also required. As with all ultrasonic techniques, the effectiveness of inspection relies on a high level of surface cleanliness and it is essential that all deposits and scale are removed from the bore of the tube prior to inspection. In ideal conditions, defects as small as 1.5 mm diameter and 0.1 mm in depth can be detected. Tubes made of virtually any material and in the range of 9 mm to 50 mm ID can be inspected. Tubes outside this range can be appraised for suitability on request. Production rates depend on factors such as tube cleanliness, tube length and the number of defects encountered but are typically in the region of 100 tubes per 12 hour shift.


Applications include the inspection of ferrous and non-ferrous tubes found in heat exchangers throughout the oil, gas petrochemical and power generation industries.