Electromagnetic ultrasonic thickness probes measure wall thickness in pipelines and pressure vessels without couplant. When an electromagnetic ultrasonic thickness probe faults, readings may drift, disappear, or become noisy. Common causes include coil damage, magnet degradation, cable breakage, connector corrosion, poor shielding, and thermal overload.

Typical symptoms are unstable echoes, low signal-to-noise ratio, sudden thickness jumps, or no echo. These can come from an open or shorted coil, cracked magnet, loose connector, or damaged matching layer. Heat may demagnetize the magnet or degrade insulation; impact can deform the coil.

Start diagnosis with visual inspection. Check housing, wear plate, cable, and connector for cracks, burns, corrosion, or looseness. Measure coil resistance and compare it with specifications. Test cable continuity and shielding. Use a calibration block to verify echo shape and thickness accuracy. Adjust gain, frequency, and gates before blaming the probe; the fault may be in the instrument, couplant, or test surface.

Maintain probes by keeping connectors clean and dry, avoiding sharp bends, and using thermal protection. Replace damaged cables and worn wear plates. Store probes in cases. For high-temperature inspection, follow cooling and duty cycles. Regular calibration and trend monitoring detect early degradation, reduce downtime, and prevent false readings. This practice improves safety and asset integrity. Regular checks prevent costly failures.