| ABSTRACT: | ULTRASOUND SIMULATION HELPS TUBE MANUFACTURERS TO CALIBRATE THEIR NDT
SYSTEMS
S.Deutsch1, P. Gerard2, and B.Bisiaux
1Vallourec Research Center, Aulnoye-aymeries, France; 2 Valtimet, Venarey Les Laumes, France
For certain ranges of small diameter and thin wall thickness tubes, the Snell Descartes laws (where the
ultrasonic field is considered as a thin beam) and the operators experience in ultrasonic testing are
sometimes inadequate for calibrating the NDT system. The beam width combined with the small radius of
the tube in fact creates several different angles of refraction in the stainless steel tube and causes the beam to
widen. For the NDT operator, the signal from the internal and external notches can be easily confused with
background noise and the usual solutions for separating signal from noise are useless here. The CIVA
simulation software (developed by the CEA) is an invaluable aid to understanding and visualizing the
phenomenon. It makes it easier to find solutions and test their effectiveness in the detection of the notches.
The results of these simulations enable us to guide the operator in calibrating the NDT system. In this article
we examine the case of the ãw19 x 1.20 mm stainless steel tube for which, after several hours of calibration,
it wasn't possible to find the right settings. The simulations allowed us to understand the acoustic
phenomenon and, working closely with the NDT manager of the plant, try and find a solution.
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