In this paper, Fuzzy decision rules, in the context of novelty detection, aim to increase efficiency and reliability related to defect identification associated with a set of A-Scan signals, obtained from a welded test piece in a non-destructive inspection using the Time-of-Flight Diffraction (ToFD) ultrasound technique. The result consisted in assigning a probability that a given analyzed signal was related to some non-conformity. ToFD ultrasonic signals from five types of defects indicated the method’s efficiency. Keywords— Non-Destructive Inspection, Signal Processing, Novelty Detection, Fuzzy Logic.

Sistema Fuzzy para Detecção de Novidades em Inspeção Não Destrutiva por Ultrassom

Based on the study and analysis of technologies and technical means for transporting oil and gas through main pipelines, energy and material-saving methods of their construction are scientifically substantiated. A method for designing trunk oil and gas pipelines with variable wall thickness is proposed, which is possible under the conditions of the current interstate standard GOST 31447-2012. The technique is based on the use of methods of mathematical and statistical modeling and construction of a multifactor experiment and processing of experimental data. Based on the results of the construction of the model, the optimal parameters for the construction of pipelines were found, new technical solutions were proposed that would significantly reduce the energy and material consumption of laying pipes during one run, i.e. between transfer pumping stations.

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Energy and material saving technologies for construction of main pipelines for oil and gas transportation

During construction, reconstruction and technical inspection of vertical steel tanks (VST), all wall butt weld joints are subjected to ultrasonic testing to detect internal defects or flaws. The considerable length of examined welds (it can exceed 3,000 m) necessitates the development and implementation of mechanized and automated inspection systems that can increase the rate of testing and documentation of results. Systems of mechanized and automated ultrasonic echo-testing do not support the detection of all defect types and reliable determination of their geometric parameters. The Time-of-Flight Diffraction (TOFD) technique makes it possible to estimate the height of the defect regardless of its type and orientation. However, the application of TOFD technique for welds with non-equal wall thickness is complicated by the fact that the standard software of flaw detectors (‘depth calculator’) does not consider this non-uniformity. The authors have developed the testing procedure to overcome this limitation and to determine the depth of defects in the welds with non-equal wall thickness by TOFD technique using the standard ‘depth calculator’. An experimental verification of this technology confirmed the correctness of the calculations. The inspection scheme and calculation of the depth of discontinuity boundaries using the TOFD technique were tested using the example of the welded joint of the walls with non-equal thickness of the 10,000-m3 tank under construction. The thickness of the walls was 12 and 14 mm; 8 and 10 mm. The inspection of the real facility has confirmed good detection of defects and high reliability of the results.

D.A. Neganov

Papers

TOFD technique application to examine welded joints with non-equal wall thickness of the vertical steel tanks