Cscans

C-scan, or C-scans in plural, is a non-destructive testing imaging method used in ultrasonic testing to produce a two-dimensional plan-view map of a specimen at a selected depth or time window. It provides a top-down view of internal features rather than a cross-section.

Principle: An ultrasonic transducer emits pulses that travel through the material and reflects from internal features, flaws, or boundaries. The time-of-flight or signal amplitude is recorded at many surface positions as the transducer is scanned. By gating the data to a fixed depth range (a time gate), the collected responses are displayed as an image in the x-y plane, with brightness or color representing the strength or travel time of reflections at that depth.

Equipment and methods: C-scans can be produced with immersion or contact scanning, using single-element or phased-array transducers. Scanning can be manual or automated, and phased-array systems can steer and focus beams to cover larger areas and interpolate data. Modern systems often store and process data to generate rapid C-scan images.

Interpretation and uses: The resulting image helps identify corrosion, delamination, inclusions, or thickness variations at a given depth. C-scans are widely used in aerospace, oil and gas, power generation, and inspection of welds and composite materials, providing quick area surveys and documentation of defect locations.

Advantages and limitations: C-scans offer fast visualization of internal conditions over large areas and yield location-specific information. Depth resolution depends on the gate width and transducer bandwidth. Limitations include reliance on good acoustic coupling, potential challenges with complex geometries, and attenuation in thick or highly scattering materials.