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Title: Method and apparatus for detecting external cracks from within a metal tube

Abstract

A method and tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is described for the detection of external sidewall cracks and other anomalies in boiler tubes and other enclosures. The invention utilizes the concept of radar backscatter rather than eddy-currents or ultrasound, which are sometimes used in prior art crack-detection methods. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to -40 dB in thin-walled boiler tubes.

Inventors:
 [1]
  1. (Albuquerque, NM)
Publication Date:
Research Org.:
SANDIA CORP
OSTI Identifier:
873919
Patent Number(s):
US 6271670
Application Number:
09/246,262
Assignee:
Sandia Corporation (Albuquerque, NM) SNL
DOE Contract Number:  
AC04-96AL85000
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
method; apparatus; detecting; external; cracks; metal; tube; tool; continuous; electromagnetic; wave; transverse; magnetic-dipole; source; coaxial; electric-dipole; receiver; described; detection; sidewall; anomalies; boiler; tubes; enclosures; utilizes; concept; radar; backscatter; eddy-currents; ultrasound; sometimes; prior; crack-detection; methods; numerical; study; distribution; fields; direct; transmission; reduced; free; space; diameter; dipole; sufficiently; detect; scattering; loss; -40; db; thin-walled; magnetic wave; detection methods; detection method; transverse magnetic; electromagnetic wave; metal tube; free space; boiler tubes; axial electric; /324/

Citation Formats

Caffey, Thurlow W. H. Method and apparatus for detecting external cracks from within a metal tube. United States: N. p., 2001. Web.
Caffey, Thurlow W. H. Method and apparatus for detecting external cracks from within a metal tube. United States.
Caffey, Thurlow W. H. Tue . "Method and apparatus for detecting external cracks from within a metal tube". United States. https://www.osti.gov/servlets/purl/873919.
@article{osti_873919,
title = {Method and apparatus for detecting external cracks from within a metal tube},
author = {Caffey, Thurlow W. H.},
abstractNote = {A method and tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is described for the detection of external sidewall cracks and other anomalies in boiler tubes and other enclosures. The invention utilizes the concept of radar backscatter rather than eddy-currents or ultrasound, which are sometimes used in prior art crack-detection methods. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to -40 dB in thin-walled boiler tubes.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2001},
month = {8}
}

Patent:

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