The paper deals with the detection and sizing of
small transversal cracks in hydrocracking units.
The minimum sensitivity code requirements for the
tests were based on 4 4 0.3 mm planar discontinuities.
This level of sensitivity was significantly
higher than the normal requirements for sidedrilled
holes from ASME Code Case 2235-9: Use of
Ultrasonic Examination in Lieu of Radiography,
Section V, Article 4; the difference was at least
12 to 18 dB (ASME, 2005). Special test blocks
were prepared with electric discharge machining
slits embedded in the weld thickness at different
depths. Time of flight diffraction and phased array
testing procedures were validated on these blocks.
Height sizing was important in the testing as
required by ASME Code Case 2235-9 (ASME,
2005). Both techniques optimized on the test
blocks were able to detect and size small transversal
cracks. Diffracted echoes were essential for
sizing the height of cracks using the phased array
ASME, Code Case 2235-9: Use of Ultrasonic Examination in Lieu of Radiography;
Section V, Division 4, American Society of Mechanical Engineers,
New York, New York, 2005.
ASME, Rules for Inservice Inspection of Nuclear Power Plant Components;
Section XI, Mandatory Appendix VIII, Supplement 2, American Society of
Mechanical Engineers, New York, New York, 2010, p. 295.
Dube, N. (ed.), “Introduction to Phased Array Ultrasonic Technology
Applications: R/D Tech Guideline (Advanced Practical NDT Series),”
Quebec, QC, Canada, R/D Tech, Inc., 2004.
Klyuev, V. V. (ed.), Handbook of Nondestructive Testing, Russian Society for
Nondestructive Testing and Technical Diagnostics, Moscow, Russia, 2005.
Komura, I., T. Hirasawa, S. Nagai, J. Takabayashi and K. Naruse, “Crack
Detection and Sizing Technique by Ultrasonic and Electromagnetic
Methods,” Nuclear Engineering and Design, Vol. 206, Nos. 2–3, 2001,
Krautkrämer, H. and J. Krautkrämer, Ultrasonic Testing of Materials, 3rd ed.,
Springer-Verlag, Berlin, Germany, 1985.
Lafontaine, G. and F. Cancre, “Potential of Ultrasonic Phased Arrays for
Faster, Better and Cheaper Inspection,” NDT.net, Vol. 5, No. 10, 2000,
Sharp, R. S., “Research Techniques in Non-destructive Testing,” Vol. IV,
Academic Press, New York, New York, 1980.
Uberall, H., “Interference and Steady-state Scattering of Sound Waves,”
Handbook of Acoustics (ed. M. J. Crocker), John Wiley and Sons, Inc.,
Hoboken, New Jersey, 1998, pp. 47–59.
Wilcox, P. D., C. Holmes and B. W. Drinkwater, “Advanced Reflector
Characterization with Ultrasonic Phased Arrays in NDE Applications,”
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol.
54, No. 8, 2007, pp. 1541–1550.