Advanced NDT Techniques for Asset Integrity

Conventional NDT (manual UT, radiography, MPI) remains the workhorse of industrial inspection, but advanced techniques offer step-change improvements in detection sensitivity, sizing accuracy, coverage speed, and data quality. For aging assets, where degradation may be subtle and the consequences of missed defects are severe, advanced NDT justifies its higher cost.

PAUT uses multiple ultrasonic elements fired in programmable sequences to sweep and steer the ultrasonic beam electronically. Advantages over conventional UT: Full volumetric data capture in a single scan; electronic beam steering without moving the probe; superior defect sizing through sectorial scanning; digital data record for comparison between inspection intervals.

Applications: Weld inspection, corrosion mapping, crack detection and sizing in nozzles and welds, tube inspection.

TOFD uses pairs of probes (transmitter and receiver) placed on either side of a weld. Defects are detected by diffraction signals from their tips, not by reflection. This makes TOFD highly effective for detecting and accurately sizing vertically oriented (lack of fusion, cracks) defects.

ToFD is particularly powerful for sizing crack height — more accurate than conventional UT pulse-echo. Widely used in pressure vessel fabrication inspection and periodic in-service inspection of welds in critical service.

PEC allows wall thickness measurement through insulation and coatings — without removal. A pulsed electromagnetic field penetrates insulation and the steel, measuring average wall thickness over a footprint of 5-10 cm.

PEC is the primary screening tool for Corrosion Under Insulation (CUI). Areas of concern are identified by PEC, then confirmed by localized insulation removal and conventional UT. This dramatically reduces the cost and scope of CUI inspection compared to mass insulation removal.