Multi-modes consists in taking advantages on geometries in order to better visualize indications
Take advantage of sample geometries
Weld inspection with ultrasonics is a standard in many industries. Most of the time, array probes are placed in contact with the part under test using a wedge. Weld inspection with common ultrasound techniques such as phased array often requires multiple probes to achieve full coverage of the weld being tested. This is typically due to the need for multiple “skip modes” to achieve detection of defects with differing orientations. A distinct benefit of TFM (Total Focusing Method) is its ability to allow imaging in multiple skip, or wave, modes with a single acquisiton. Many times this can element the need for multiple probes, while at the same time increasing your probability of detection.
Here is shown an example from a girth weld in a carbon steel pipe. From the macrography, a lack of fusion is clearly visible. The ultrasonic images from three modes (TT, TTT and TTTT) are displayed below. The flaw is clearly more properly characterized using TTT or TTTT modes.