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c. Tube Testing with IRIS


IRIS-testing (Internal Rotating Inspection System) is used for flaw detection and wall thickness measurement of ferrite tubing in heat exchangers. The variation of permeability in ferrite material causes disturbing signals when using eddy current or other electrical testing methods. Because of the disturbing signals the accuracy of those methods is not sufficient for evaluation of the flaw size or flaw characteristics, not even to detect them all

IRIS testing is based on ultrasound and is not impacted for electric properties of material. Only the material characteristics, which affect for ultrasound, should be taken in consideration. Those are e.g. the cleaning of tubing. There should not be any deposition or other dirties inside the tubing which could absorb the ultrasound and avoid the ultrasound to reach the front and back wall of the tubing material.

Using the IRIS-testing the absolute remaining wall thickness will be measured around the tube circumference. Each rotation of the mirror of the IRIS-probe will cater the whole circumference of the tube wall. The wall thickness will be measured for the whole length of the tube when moving the IRIS-probe from the inlet to outlet of the tube. At the same time the whole circumference of the tube wall will be tested.

The IRIS probe consists of a rotating 45-degree mirror that redirects the ultrasonic beam into the tube wall. The mirror is driven by a small turbine that rotates at about 50 rev/s. The turbine is set in motion by the pressure of water pumped inside the probe. As the probe is pulled, the spinning motion of the mirror results in a helical scan path, so from one revolution to the next, the complete surface of the tube is covered.

The ultrasound beam is generated by the transducer; the beam hits the mirror and is reflected at a 45-degree angle. Because no mirror is perfect, a small echo is reflected back to the transducer. Other than that, ultrasound waves are partially reflected by the tube internal wall (ID) but also transmitted through the wall, and finally reflected by the tube external wall (OD). Using the speed of propagation of ultrasound in the tube material, the wall thickness can be calculated by using the time-of-flight difference between OD and ID echoes.

Axionz is conducting training and certifications in IRIS.

Course contents:

  • Introduction about IRIS
  • Separation of ID or OD flaws and damage areas
  • Depth of the flaws
  • Flaw types ( corrosion, erosion, vibration, wall thinning,...)
  • Damage grade; local or areal
  • Position of damage in direction of the tube length and tube circumference
  • Flaw depth histograms showing the average grade of wall thickness thinning
  • Tube map's with classifications of tubes according damage grade and/or flaw types
  • 3D presentation of testing results including damaged areas, individual flaws or flaw types.

Contact office for Course fee and Course duration