Techniques designed specifically for corrosion detection and assessment in piping are Long Range Ultrasonic Testing (LRUT), ElectroMagnetic Acoustic Transducer (EMAT) scanner and the flux leakage based pipe scanner.
Long Range UT uses low frequency ultrasonic guided waves to survey long sections of pipe. Often this amounts to tens of metres from a single test point, in either direction. This minimises access needs and surface preparation for inspection which translates into substantial savings.
Emat probes transmit ultrasonic signals around the pipe circumference as they are carried along a pipe by a motorised scanner. Ultrasonic (thickness) data is recorded and displayed by a computer. This system can scan up to 500m of pipe per day and provide quantitative thickness data and corrosion detection, even under pipe supports. The probes are "non contact" and work through light rust and paint.
Pipescan uses magnetic flux leakage to detect corrosion pitting damage in carbon steel piping up to 19mm thick. The system allows the operator to carry out a rapid (100m in four shifts), cost effective survey of non insulated piping to identify corroded areas.
Tube inspection with automated eddy current and remote field eddy current systems is both fast and effective. Although the tube scanners require the boiler or heat exchanger to be opened, the high inspection speed still saves cost by minimising down-time.