Tube Inspections Services have been carried out by Advanced NDT Solutions. The line of techniques includes:

• Remote Field Technology (RFT- Ferrous Tubing);
• Near Field Testing (NFT – Fin Fans)
• Eddy Current Testing (ECT- Non-ferrous Tubing);
• Internal Rotary Inspection System (IRIS-Ultrasonic Testing all materials).

Eddy Current Testing (ECT) : This is the most common technique utilized for the inspection of non-ferrous tubing, the technology is very reliable and can determine tube condition in relation to general wall reduction and the presence of local defects such as pitting and cracking with a high probability of detection when using the correct probes.

Remote Field Testing (RFT): This is a fast reliable screening tool for the condition assessment of ferrous tubing (carbon steel, ferritic stainless steel and Duplex). Works typically at very low frequencies (100 Hz to 1 kHz) and very high signal gains (> 80 dB) can inspect up to 12 mm (1/2 in.) of carbon steel pipe. Typically two channels are used for examination. To improve inspection results it is always advised to perform cleaning of the internal bore of tubes with some form of water jet lancing tool.

Internal Rotary Inspection System(IRIS): This is an ultrasonic technique for condition assessment of tubing of all materials with a tube wall thickness greater than 1mm. The technology can precisely measure remaining wall thickness from corrosion, erosion, pitting and wear associated with baffle supports. However it requires a very high standard of cleaning and is a much slower technique than the ECT or RFT test methods. It is not possible to detect cracking with IRIS. The system uses a rotating turbine head with a transducer sending a single into tube wall via an angular mirror. The image displayed can be seen as a B-Scan (Cross-sectional view) and also in a C-Scan (Development of Longitudinal axis of tube).

IRIS Technique

 Near Field Testing (NFT – Fin Fans):

NFT probes operate within the same frequency range as Remote-Field Testing (RFT) probes.
NFT technology uses two coils (a transmitter and a receiver). Typically the receiver coil is close to the transmitter coil, taking advantage of the transmitter’s near-field zone that is, the zone where the magnetic field from the transmitter coil induces strong eddy currents, axially and radially, in the tube wall.
NFT is specifically suited to detecting corrosion, erosion, and pitting inside carbon steel tubing. NFT is perfect for fin-fan tube heat exchangers because eddy currents do not go through the wall of the tube. NFT is also much more sensitive to defects close to structures such as support plates and tubesheets.