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.

Various components are necessary to "build" an IRIS probe. The components are interchangeable and must be chosen according to the tube dimensions.

To build an IRIS probe, the following components are necessary:

• Turbine head (TUA)
• Ultrasound transducer (TUB)
• Centering device (TUC)
• Probe cable (TUD).

TUA -Turbine heads

IRIS turbines are propelled by water pressure to make them rotate at approximately 40 r/s. They include a 45° angled mirror that deflects the ultrasonic beam towards the tube wall.

TUB - Ultrasound transducers

IRIS transducers are focused immersion transducers with an external diameter of 3/8 in. (9.53 mm) and an element diameter of 1/4 in. (6.35 mm). They are available in 3 different central frequencies and 2 focal lengths.

TUC - Centering devices

TUD - Probe cables

IRIS probe cables have two functions: they supply the water pressure required by the turbine; and they carry the ultrasonic signal with the use of a small coaxial cable. The coaxial cable has a Microdot connector on the probe end and a BNC connector on the instrument / pump end. The water is supplied by the pump through a quick-connect 1/8 in. brass fitting.