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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
Issue Date:
Research Org.:
Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
OSTI Identifier:
873919
Patent Number(s):
6271670
Application Number:
09/246,262
Assignee:
Sandia Corporation (Albuquerque, NM)
Patent Classifications (CPCs):
G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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}
}

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Works referenced in this record:

Modeling of eddy current probe response for steam generator tubes
journal, November 1999


Overview of steam generator tube degradation and integrity issues
journal, November 1999