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Muravin G.,Margan Physical Diagnostics Ltd. | Mizrahi I.,Margan Physical Diagnostics Ltd. | Frage N.,Ben - Gurion University of the Negev
Materialwissenschaft und Werkstofftechnik | Year: 2010

QAE NDI technology has been adapted to revealing, identifying and assessing one type of previously non-predictable failure of high energy equipment and piping, known as crack type IV. The research established the following: Cracks of type IV correspond to transverse shear crack mode II, according to the classification used in fracture mechanics and the physics of solids. The length of crack mode II jumps, the velocity of it propagation are significantly higher than in case crack mode I under the same loads. The earliest quantitative statistical Acoustic Emission (AE) indications and peculiarities necessary and sufficient to reveal cracks in specimens loaded by tension or shear loads, especially the differences in the AE power, median Energy, Average Frequency and Hit Rate of the AE signals flow. etc. Based on the findings described above have been formulated requirements and technological solutions for revealing, typifying and assessing crack IV. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Muravin G.,Margan Physical Diagnostics Ltd. | Muravin B.,Margan Physical Diagnostics Ltd. | Lezvinsky L.,Margan Physical Diagnostics Ltd.
Rivista Italiana della Saldatura | Year: 2010

Increasingly severe requirements for the safety and reliability of potentially dangerous equipment and structures stimulated us to create and develop a new AE technology that would also make it possible to reveal, identify and assess the danger level of individual and interacting flaws according to fracture mechanics criteria. We started this work at the 1980s and created our "The Quantitative Acoustic Emission NonDestructive Inspection (QAE NDI) technology". These innovations made it possible to carry out pioneer investigations and establish previously unknown dependences, phenomena and criteria. In this paper we shall describe a number of cases of catastrophic failures, peculiarities and results of using QAE NDI for inspection and assessment condition of welded structures, the results of verification tests.

Inspecting for fracture hazards by detecting a presence of at least one flaw development process in an equipment under inspection, the flaw development process being corrosion product nucleation and development, pitting, plastic deformation development, and/or micro-cracking. Detecting the presence of the flaw development process includes (a) determining at least one characteristic acoustic emission (AE) signature associated with a respective flaw development process, and (b) measuring an AE from each of a plurality of locations within the equipment. Presence of the respective flaw development process is identified only when the measured AE conforms to the characteristic AE signature within a predetermined tolerance. A fracture hazard is determined to exist only when (a) a quantity of the identified flaw development processes exceeds a first predetermined threshold and/or (b) a magnitude of at least one of the identified flaw development processes exceeds a second predetermined threshold.

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