Demonstration of the Applicability of Nondestructive Microwave Testing to the Long-Range Inspection of Inner-Surface Cracks in Tubes

Abstract

This study evaluated the applicability of nondestructive microwave testing method for the long-range detection of inner-surface cracks in metallic tubes. Two seamless straight tubes 7 m in length and 23.0 mm in inner diameter were prepared, and arti cial circumferential slits penetrating the tube walls were introduced. A probe to propagate microwave inside the tube, designed based on three-dimensional nite element simulations, was attached to an end of the tube, and the re ections of the microwave propagating inside the tube were measured using a network analyzer. The experiments con rmed clear re ections due to the slits situated 6 m away from the probe. Furthermore, imposing a signal processing method to compensate for the dispersion of the microwave clari ed the re ections and enabled the slit to be localized quantitatively from the time-of-ight of the re ections.

Design of a simple side-incident TE11 mode microwave probe for nondestructive pipe inspection

“…In particular, a back propagation neural network was trained in that study to quantitatively evaluate the depth and length of a wall thinning defect using the extracted resonant frequencies of TM 01 microwave signals and showed good performance. Previous studies have proven the feasibility of this method in detecting wall thinning [15][16][17], cracks [18,19], corrosion under insulation [20], and leakage in buried pipes [21] and biofouling [22,23]. In particular, microwaves in the TM 01 mode with the axial surface current density and in TE 01 mode with the circumferential surface current density on the pipe wall showed high sensitivity to circumferential [18] and axial cracks (slits) [19] with the width about 1 mm, respectively.…”

“…Previous studies have proven the feasibility of this method in detecting wall thinning [15][16][17], cracks [18,19], corrosion under insulation [20], and leakage in buried pipes [21] and biofouling [22,23]. In particular, microwaves in the TM 01 mode with the axial surface current density and in TE 01 mode with the circumferential surface current density on the pipe wall showed high sensitivity to circumferential [18] and axial cracks (slits) [19] with the width about 1 mm, respectively. A recent study [24] proved that microwaves in TM 01 mode and TE 01 mode were feasible to detect nonpenetrating circumferential and axial cracks with the width smaller than 0.3 mm, respectively.…”

Research of Crack Defect Detection in Metal Pipes Based on Microwave Antenna Array

“…where U n ðθ, φÞ and G n ðθ, φÞ denote the radiation intensity and power gain of the nth element [22][23][24][25].…”

Measurement of the Void Size Between Wall Tiles and Concrete Through Nondestructive Inspection Using Electromagnetic Waves

“…These techniques [7] can detect voids or cracks in concrete [8]. Furthermore, the void depth and thickness [9] can be evaluated using a time/frequency domain network analyzer [10,11] to calculate the position of foreign objects in the structure. However, this method is both complex and expensive.…”