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IRIS Inspection of pipes and tubes

Internal rotary inspection system (IRIS) is an ultrasonic method for the non-destructive testing of pipes and tubes.

The IRIS probe is inserted into a tube that is 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.

How it works

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 the pressure of water being pumped in. As the probe is pulled the spinning motion of the mirror results in a helical scan path.

Where is IRIS used?

Most commonly used in boilers, heat exchangers, and fin-fan tubes. Often used as a back-up to electromagnetic examination of tubes, to verify calibration and accuracy. Especially useful as a follow-up to remote field testing due to the full sensitivity near tube support structures provided by IRIS.

How long does it take?

The IRIS probe must be moved very slowly at approximately 1 inch per second, or 2.5 cm/s, to enable it to produce very accurate results - wall thickness measurements typically accurate to within 0.005 inch, or 0.13 mm

What preparation is required prior to Inspection?

Before the examination, tubes must be cleaned on the inside to bare metal. A supply of clean water is needed, typically at a pressure of 60 psi, or 0.4 MPa. Dirt or debris in the water may cause the turbine to jam.

What else do you need to know about IRIS?

  • Works in metal tubes
  • Through hole is difficult to detect by using this method
  • Operates in temperatures above freezing
  • Can pass bends, but will not detect defects in bends
  • Not sensitive to cracks aligned with tube radius
  • Gives accurate level of wall loss and corrosion.


We pride ourselves on the high quality of application and testing by our experienced technicians. Our workforce is fully qualified to current standards and work to approved procedures and control checks. Environmental and health & safety issues are of paramount concern to all staff working on your site, with expert consultation always available.

ITCL offers a comprehensive 24hr in-house and on-site service.

Contact a member of the ITCL team on 0151 356 7118 for more information.

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Iris Inspection

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For information on any of our services please contact us on +44 151 356 7118