Also known as: GWT, LRUT, long-range ultrasonic testing, guided wave ultrasonics.
How it works
A ring of transducers clamped around the pipe launches a wave that fills the whole wall and travels along it. Every change in cross-section (welds, supports, corrosion patches) reflects part of the energy back. Welds and features are used as reference reflectors, so corrosion appears as an unexplained signal at a known distance.
Where it is used
Corrosion under insulation programs, buried and cased pipelines at crossings, offshore risers, and screening long runs of piping before targeted excavation or scaffolding.
Guided wave in AMPS
Guided wave results point to locations that need follow-up; in AMPS those follow-up jobs are created against the same asset so the screening report, the follow-up UT and the repair record share one history.