Eddy Current (ET)

Eddy current is the most common method of inspecting non-

ferrous heat exchanger tubing such as brass, copper and stainless

steel. Eddy current testing is very sensitive to cracks, wall loss due

to erosion and corrosion, and can easily distinguish between OD

and ID wall losses.

Remote Field (RFT)

Remote field testing is used on ferrous tubes such as carbon steel

and duplex stainless steel and is a “through-wall” technique,

meaning the signal travels through the tube wall and back in again.

RFT is very useful to determine general wall loss and pitting, but

cannot differentiate between ID and OD defects. As a result, RFT is

often backed up with a secondary method, which may be

examination of a pulled tube, video inspection, or IRIS.


IRIS is an ultrasonic technique that uses a tiny spinning mirror and

water to transmit an ultrasonic pulse against the inside of the tube wall.

The signal travels through the tube wall and reflects off the outer

surface, and provides an extremely accurate and very easily interpreted

image of the remaining wall thickness. IRIS requires extremely clean

tubes to obtain a good signal and is much slower than eddy current or

RFT. As a result, it is often used as a final verification method or is used

sparingly on selected tubes

Nordsee's owns and operates state of the art Olympus MS5800 tube inspection equipment which can run eddy current,

remote field, and IRIS inspections without the need for a second unit.

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