Ultrasonic Thickness Testing

Ultrasonic thickness testing measures the remaining wall thickness of steel structural elements by transmitting an ultrasonic pulse through the material and measuring the time for the echo to return from the opposite face. This measurement, accurate to ±0.1mm, directly quantifies the section loss due to corrosion, the critical parameter for determining the residual structural capacity of steel members in aggressive environments.

For marine and coastal infrastructure, industrial facilities, and aged steel-framed buildings, corrosion-induced section loss is typically the controlling factor in structural adequacy assessment. UTT provides the data to answer the essential question: how much steel remains, and is it sufficient to carry the required loads? Without this measurement, engineers must either assume worst-case section loss (resulting in over-conservative conclusions and unnecessary intervention) or ignore section loss entirely (resulting in unconservative conclusions and unquantified risk).

TRSC uses UTT systematically across structural elements to develop corrosion profiles, maps showing where section loss is concentrated, where it is minimal, and how it varies across the structure. These profiles are integrated into structural analysis models to determine residual capacity based on actual remaining sections rather than nominal design sections. At Marina Mirage, UTT measurements on marine-exposed steel elements provided the section loss data that enabled quantified capacity assessment of structures serving well beyond their original design life.

UTT is a rapid, portable, and non-destructive technique. A single measurement takes approximately 5 seconds, allowing systematic surveys of large steel structures within practical timeframes. The technique requires access to only one surface of the element being measured, making it suitable for steel members where the opposite face is inaccessible, embedded in concrete, submerged, or in confined spaces.