Spatial Resolution of GWT

Guided wave testing uses two primary elements in defect detection. The first is a 2-to-1 signal-to-noise ratio for defect detection. The Magnetostrictive sensor (MsS) guided wave testing method has low background noise to achieve a high signal-to-noise ratio of ≥50 dB for end-reflected signals of pipes. The second aspect is spatial resolution that allows for detection of any defects near the geometric feature.

For example, Figure 1 demonstrates an 8 NPS and schedule 40 stainless steel pipe that was tested. Figure 2 shows data acquired with both MsS encircling and sector probes. The defect is detected at approximately 4.1 m. with two encircling probes installed at either end of the pipe. 4-inch MsS sector probe is used to verify the detected defect by rotating 360˚ along the circumference. The discrete defects are detected at approximately 10 cm behind the weld. This example demonstrates the importance of spatial resolution in guided wave testing.