2014. . No. 4(66) - Dec 2014, pp. 6-9
Zebra and Rainbow Example of Image Quality Standard in TOFD and Phased Array Technique
Image quality is a fundamental parameter to evaluate the correct setup of the equipment referred to the calibration test. In TOFD technique the grey level, as contrast between positive and negative phase, is the main parameter for detection and sizing of defects. Three quality classes have been proposed to graduate the grey level. In addition tips resolution is also expressed as a quality parameter. The first class has zebra as an example of grey contrast. In Phased Array technique, image quality of the reference indication is characterized by a spectrum of colours. This image represents an echo dynamic curve of the reference reflector through which the size of findings is estimated. The first class has rainbow as an example of image standard. The paper presents with different examples the need to establish a standard quality of an image, in particular in the evaluation of the procedure demonstration. This will avoid the rejection of TOFD and Phased Array maps at the final stage of the constructions as it has happened also recently, causing delay and heavy economic consequences.
Keywords: non-destructive testing, ultrasonic flaw detection, defect sizing
- A.Filosi, G. Nardoni, P.Nardoni. IDN 94-Sizing and flaw characterization with TOFD technique in the examination of 360 mm SAW weld 2-1/4 Cr Mo Reactor. Evaluation of planar and volumetric flaw through TOFD and Pulse Echo technique. Conferenza Nazionale sulle Prove non Distruttive, 2005.
- G. Nardoni, P.Nardoni. Accuracy Capability of TOFD Technique in Ultrasonic Examination of Welds. 15th World Conference on NonDestructive Testing, Rome 2000.
- G. Nardoni, M. Certo, P.Nardoni, M. Feroldi, D. Nardoni. Time of Flight Diffraction and Phased Array Techniques for the Detection of Small Transversal in Hydrocracking Units Welds in Cr Mo V Steel. Materials Evaluation, vol.69, no 7, 2011.
- Sharp R. S. Research Techniques in Non-Destructive Testing, vol. IV, 1980.
- Encyclopedia of Acoustics. New York, John Wiley & Sons, Vol. 1, 1997.
- ASME Code Sec. V, art. 4, Code Cases 2235.9. Use of Ultrasonic Examination in Lieu of Radiography.
- Introduction to Phased Array ultrasonic Technology Application: R/D Tech Guideline. Quebec City, Canada, 2004.