Ultrasonic control of welded joints in a Du800-type pipeline. Part II: Improving image quality and comparison with X-ray testing results

It has been shown in the first part of the article that the DFA method in its version intended for ultrasound propagating in a homogeneous isotropic medium does not suffice for reconstructing high-quality images of reflectors in the welded joint of a Du800-type pipeline. To improve the image quality further while using the DFA method, it is necessary to determine the elastic properties of a Du800 pipeline buildup and allow for its anisotropy with respect to the propagation of ultrasound as well as the surface profile. The DFA-Y and maximum-entropy (ME) methods have been applied to increase the resolving ability and reduce the noise level. Comparing the results of ultrasonic and X-ray testing has made it possible to draw a conclusion that the former is more informative for revealing crack-like reflectors.

[1]  Jerry Avorn.  Technology , 1929, Nature.

[2]  S. Kullback,et al.  Information Theory and Statistics , 1959 .

[3]  Solomon Kullback,et al.  Information Theory and Statistics , 1970, The Mathematical Gazette.

[4]  ProblemsPer Christian HansenDepartment.  The L-curve and its use in the numerical treatment of inverse problems , 2000 .

[5]  Van Kempen,et al.  The influence of the regularization parameter and the first estimate on the performance of tikhonov regularized non-linear image restoration algorithms , 2000 .

[6]  M. P. Hobson,et al.  Maximum-entropy image reconstruction using wavelets , 2003, astro-ph/0303246.

[7]  Fadil Santosa,et al.  An inverse problem in nondestructive evaluation of spot-welds , 2006 .

[8]  P. Dumas,et al.  ULTRASONIC NONDESTRUCTIVE TESTING OF COMPLEX COMPONENTS WITH FLEXIBLE PHASED-ARRAY TRANSDUCERS , 2010 .

[9]  E. Bazulin,et al.  Application of antenna arrays and organosilicon polymers as an immersion medium for ultrasonic testing of objects with rough surfaces , 2014, Russian Journal of Nondestructive Testing.

[10]  E. G. Bazulin.  Reconstructing the Deflector Images From the Ultrasonic Echo Signals by the Maximum Entropy Method , 2014 .

[11]  E. G. Bazulin.  Ultrasonic control of welded joints in a Du800-type pipeline. Part I: Restoring reflector images by digital focusing with an antenna , 2017, Russian Journal of Nondestructive Testing.

[12]  Allowing for inhomogeneous anisotropy of a welded joint when reconstructing reflector images from echo signals received by an ultrasonic antenna array , 2017, Russian Journal of Nondestructive Testing.