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

Patent · Tue Aug 07 00:00:00 EDT 2001

OSTI ID:873919

Caffey, Thurlow W. H. ^[1]

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1. Albuquerque, NM

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.

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• DOE Contract Number: AC04-96AL85000
• Assignee: Sandia Corporation (Albuquerque, NM)
• Patent Number(s): US 6271670
• Application Number: 09/246,262
• OSTI ID: 873919
• Country of Publication: United States
• Language: English

Related Subjects

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
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