Monitoring of high temperature damage of pipe utilizing heat resistant optical fiber acoustic emission sensor

Tomoharu Hayano, Takuma Matsuo, Hideo Cho, Mikio Takemoto

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We developed a new heat-resistant optical fiber AE sensor and a homodyne Mach-Zender type laser interferometer to monitor the acoustic emission (AE) from hot members. The optical fiber coated with copper was used as a heat resistant sensor, and AEs from hot pipes were measured up to 600°C for 108 ks. The sensor was found to monitor the longitudinal mode cylinder wave which conventional PZT sensor can not monitor, when the sensing fiber was wound on the pipe. The system was utilized for monitoring AEs from crack and exfoliation of non-protective scales produced by catastrophic oxidation of Type 304 stainless steel pipe at 700°C. The cylindrical AEs were classified into two fracture types, i.e., Mode-I fracture with a crack opening vector in the circumferential direction (scale fracture) and in the radial directions (exfoliation). A number of AEs detected during cooling was found to be produced by Mode-I crack of the scales. Their sources were located using arrival time differences of L (0,2) and F (1,1) modes at 80 kHz and found to be in the zone with non-protective scales.

Original languageEnglish
Pages (from-to)560-567
Number of pages8
JournalZairyo to Kankyo/ Corrosion Engineering
Volume56
Issue number12
DOIs
Publication statusPublished - 1 Dec 2007

Keywords

  • Acoustic emission
  • Cylindrical wave
  • Heat resistant fiber
  • Mach-Zender type laser interferometer
  • Molten salt attack
  • Optical fiber AE sensor

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