What are eddy currents?
A clear introduction to eddy currents — induction, secondary magnetic field, and how defects change amplitude and phase. By Prof. Dr.-Ing. Dieter Stegemann (Leibniz Universität Hannover).
Read article →Technical Resources
Heat Exchanger Tube Inspection — Technical Resources
A curated set of technical notes and FAQ articles on heat exchanger tube inspection: eddy current testing (ECT), partial and full saturation eddy current (PSEC/FSEC), IRIS ultrasonic wall-thickness measurement, and NDT method selection by tube material and degradation mechanism.
Written by the inspection crew at DELTA TEST Middle East for engineers in refineries, petrochemical plants, fertiliser producers and power generation across Saudi Arabia and the GCC.
Eddy Current Testing (ECT, PSEC, FSEC)
ECT as one method family covering non-ferromagnetic, slightly magnetic and strongly ferromagnetic tubing. Bobbin probes, differential/absolute mode, and when a DC bias magnet is added.
Read article →PSEC vs. FSEC — What is the difference?
PSEC = partial saturation (strongly ferromagnetic, heavy wall — CS, P91, T22). FSEC = full saturation (slightly ferromagnetic, thin wall — duplex, austenitic SS with δ-ferrite, Monel). Named after the saturation state, not the magnet on the probe.
Read article →FSEC, RFT, MFT & IRIS — Comparison
How saturation eddy current, remote-field testing, magnetic flux testing and the Internal Rotary Inspection System compare on ferromagnetic and heavy-wall tubing, including ACHE finned tubes.
Read article →NDT Method Comparison for Heat Exchanger Tubes
Material and degradation mechanism drive the method choice. A compact comparison matrix across ECT, PSEC, FSEC, RFT, NFT, MFT and IRIS — including when IRIS verification is required.
Read article →False Indications in Austenitic Stainless Tubes
Cold work, forming, welding and local heat induce ferromagnetic phases (δ-ferrite, strain-induced martensite) in austenitic stainless steel. How we verify suspect indications with a magnet probe to avoid unnecessary plug-or-retube decisions.
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