Investigation of the effect of a bend on pipe inspection using microwave NDT

Guanren Chen, Takuya Katagiri, Haicheng Song, Noritaka Yusa, Hidetoshi Hashizume

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


This study investigated the effect of a bend on microwave NDT (non-destructive testing) applied for rapid pipe inspections. The factors affecting the mode conversion of microwaves due to a bend were deducted theoretically and verified through numerical simulation. Both theoretical and numerical results revealed that the mode conversion at a bend was actually determined by the frequency normalized by the cut-off frequency of an arbitrary mode (f/fc), the ratio of the curvature radius to the inner diameter of the pipe (r/D) and the bend angle (α). Subsequent experimental evaluations were performed using four groups of pipes with different inner diameters and five different bends. The effect of a bend was quantitatively evaluated by comparing the reflection signals from pipe wall thinning in a straight pipe with those in a bent pipe. The results showed that the presence of a bend led to a decrease in the reflection signal behind the bend, and the extent of decrease also depended on r/D and α of the bend. Furthermore, the length or the depth of the pipe wall thinning did not noticeably affect the decrease in reflection signal, when the bend's dimensions were certain.

Original languageEnglish
Article number102208
JournalNDT and E International
Publication statusPublished - 2020 Mar


  • Bend
  • Microwaves
  • Mode conversion
  • NDT
  • Pipe

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering


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