Proficient Inspection Services Co. Ltd.

Eddy Current Tube Testing (ECT) is widely used for testing on Non-Ferromagnetic tubes commonly in condensers, coolers and other heat exchangers. Power generation industries heavily rely on ECT to evaluate thousands of tubes in their condensers which can be inspected in a matter of few days only.

ECT uses alternating currents to drive the circumferentially wounded coils to produce eddy currents in the tubes. Changes in the eddy current flow will create a change of impedance in the coil and thus will be detected by the ECT system.

ECT is calibrated with an ASME calibration tube which has the same material grade and dimension of the tube to be inspected before inspection. ECT is highly sensitive to both internal and external defects such as pitting, holes, longitudinal cracks, stress corrosion cracking, fretting, and erosion.

Eddy Current Array (ECA) for tube testing is the most advanced eddy current inspection technique available up to date. The technique is highly optimized to inspect circumferential cracks in non-ferromagnetic tubes, which exceeds the limitation of a normal ECT bobbin probe.

Instead of having a normal circumferential coil, the ECA probe has an array of individual coils surrounding 360 degrees of the probe allowing it to detect cracks at any orientation. Cracks could be formed due to tube vibration (leading to fretting), stress corrosion, improper tube expansion, and primary defects from fabrication processes. The ECA technique uses multi-frequency channels to emphasize in detail any anomaly detected.

The inspection method requires an in-depth understanding of the electromagnetic testing technique with experience to confidently analyze and interpret the advanced eddy current signals.

Partially Saturated Eddy Current Testing (PSECT) utilizes the same probes as normal bobbin ECT probes except that it uses strong magnets to saturate the non-ferromagnetic tube walls. The purpose of the magnets is to suppress or reduce the effects of permeability from the mildly magnetic tube.

This technique is however limited to relatively low permeability materials/mildly ferritic materials only such as Duplex, SEA-Cure, Monel, 3EE60, Nickel or 400-series stainless steel. Furthermore, it is only limited to saturating up to 1.5mm of the tube thickness. If the tube is thicker than 1.5mm, the probe is not likely to provide adequate magnetic saturation of the tube wall.

Long Range Ultrasonic Testing (LRUT) is an ultrasonic technique to allow screening of long ranges of piping and identify areas of corrosion and erosion for further evaluations using other NDT methods. LRUT uses low-frequency guided waves which are transmitted from a ring of transducers mounted on a collar. Each transducer on its own will generate a flexural wave. When all the transducers oscillate/vibrate in unison a symmetrical wave is produced which will be transmitted through both sides of the LRUT collar. When there is an area of corrosion, the decreased area of the pipe will create a scattering of the incident waves in addition to reflection and mode conversion will occur. The reflected mode-converted waves will cause the waves to flex and be detected by the transducers.

Applications for LRUT are for inspecting:

• Terminal pipelines
• Cross country pipelines
• Long-in-plant process pipes
• Buried section pipes
• Road crossing
• Offshore risers

LRUT saves time and cost to inspect 100% of the pipelines by allowing to inspect non-accessible areas, and not having to remove all insulation of the pipeline.

They support conventional Non-destructive Testing services for our clients both locally and globally by our proficient inspectors. Among the NDT services provided are:

• Ultrasonic Testing (UT)
• Eddy Current Testing (ECT) Surface
• Dye Penetrant Testing (DPT)
• Magnetic Particle Inspection (MPI)
• Visual Testing (VT)