Internal rotary inspection system (IRIS) Tubing Inspection ultrasonic test method is employed for testing of pipes and tubes in boilers, heat exchangers and fin-fan tubes. The IRIS probe is inserted into a tube flooded with water, and the probe is pulled out slowly as the data is displayed and recorded. The ultrasonic beam allows detection of metal loss from the inside and outside of the tube wall.

The IRIS probe consists of a rotating mirror that directs the ultrasonic beam into the tube wall. The mirror is driven by a small turbine that is rotated by water pressure. As the probe is pulled the spinning motion of the mirror results in a helical scan path. The IRIS probe must be moved very slowly (approximately 2.5 cm/s) to produce very accurate results (wall thickness measurements typically accurate to within 0.13 mm).

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Before the examination, tubes must be cleaned on the inside to bare metal. Dirt or debris in the water may cause the turbine to jam. Works for tube diameters of 13 mm and above. Special centralizing devices are needed for larger diameters. Not sensitive to cracks aligned with tube radius.

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Benefits

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• Works on all materials, regardless of properties.

• Full sensitivity near tube support structures such as tube-sheets.

• Perfect as a backup to electromagnetic testing.

• Very accurate wall thickness measurement results.

• Most ideal for ferromagnetic heat exchanger tubes, but IRIS can be used on any metallic material.

• IRIS ultrasonic testing is perfect for metal loss measurements on both types of tubes.

• Very accurate wall thickness measurement technique

• Typical smallest detectable discontinuity is through-hole of diameter 1.6 mm equivalent.

• Can pass heat exchanger bends, but will not detect defects in bends.