Estimating the Probability of Detecting a Delamination in the Wall of Equipment Depending on the Set of Used Methods of Nondestructive Testing and Ways of Its Improvement

A method is proposed for assessing the quality of nondestructive testing and the technical condition of tanks and vessels used in petrochemical industries, depending on the methods of nondestructive testing employed in technical diagnostics. The probability of revealing a defect was used as a criterion when assessing the quality of technical diagnostics. Estimates are given for the probability of detecting a delamination in the vessel-body wall material of different area using various schemes of applying the basic methods of nondestructive testing. It is shown that the acoustic-emission method makes it possible to significantly increase the probability of detecting a delamination in the equipment wall without increasing the scope of work by virtue of local methods of nondestructive testing. A positive effect is achieved through the use of acoustic-emission testing data (the location maps and hazard levels of acoustic-emission sources) at the stage of planning the procedure of nondestructive testing during technical diagnostics of equipment.     

Inspection of fatigue defects in endurance testing of half-axles of maneuverable aircraft’s stabilizers by means of acoustic emission and tensometry

The results obtained by acoustic-emission (AE) testing and continuous tensometry in endurance testing of half-axles of maneuverable aircrafts stabilizers are described. In order to ensure the reliability of the tests, fractography of the fractures obtained is carried out along with metallographic studies of the materials structure in the zone of fracture nucleation and propagation.Translated from Defektoskopiya, Vol. 40, No. 9, 2004, pp. 3–10. Original Russian Text Copyright © 2004 by Sereznov, Maltsev, Stepanova, Kabanov, Chaplygin, Laznenko, Kareev, Kozhemyakin.     

Developing Algorithms for Estimating Strength on the Base of Imitating Structural Model of Acoustic Emission. I. Effect of Instability of Acoustic-Emission Coefficient

The task of upgrading the accuracy of physical models of elastic wave emission, which is necessary for improving methods of acoustic-emission (AE) testing of materials and structures, is closely related to the problem of instability and ambiguity of measured parameters. We suggest solving the problem by modifying the models and creating new physically justified algorithms for digital processing of AE data. The paper considers underlying mathematical and physical principles of the algorithms and their applications to specific cases of bodies tested under constants loads and loads growing with constant rates. The algorithms have been tested on samples with adhesive bonds and on pressurized vessels.     

Correlations between parameters of acoustic-emission signals and corrosion damage in aluminum alloys

Results of the studies of correlations between different parameters of acoustic-emission signals and the degree of corrosion damage of an aluminum alloy exposed to two different active media are presented. The critical values of the acoustic-emission count rate and the total acoustic-emission signal that correspond to the elastic-plastic transition and subsequent active creation of microcracks are obtained for Д16M. The limiting values of the known Ivanov-Bykov criterion, which characterizes the moment when corrosion cracking starts in Д16M, are calculated. The acoustic-emission technique may be used for nondestructive testing of corrosion damage on inner surfaces of piping in poorly accessible structures.     

Studies of the fracture process in composite structural elements based on strain measurements and the acoustic-emission technique

The results of cyclic tests of structural elements (SEs) with a stringer, which are made of the composite material (CM) Organit-10T and are parts of an aileron from an ë-80Éè aircraft, are considered. As SEs are broken, information is obtained simultaneously from acoustic-emission (AE) and tensometric equipment and measurements of the fatigue cracks opening are carried out. An insignificant increase (by 0.25 µm) of the crack opening generates a considerable flow of AE signals. These signals are processed using cluster analysis, which makes it possible to separate the signals emitted by a propagating fatigue crack in the stringer region from the signals arriving from the region of the fracturing gripping jaw.Translated from Defektoskopiya, Vol. 40, No. 9, 2004, pp. 11–18. Original Russian Text Copyright © 2004 by Sereznov, Stepanova, Lebedev, Chaplygin, Katarushkin, Kozhemyakin.     

Health monitoring of aboveground storage tanks’ floors: A new methodology based on practical experience

An acoustic-emission technique is developed as a nonintrusive method and suitable maintenance-planning tool for inspecting the floors of storage tanks in order to find an optimum service-period duration. This paper deals with the methodologies and experiences gathered from field testing of above-ground storage tanks via the acoustic-emission technique conducted in refineries until now. The results of field testing conducted to date has led us to create a grading system for the purpose of maintenance of tank floors. The location of leak and corrosion sources that is based on the arrival-time difference in the acoustic-emission measurement is discussed, and findings gathered through source-location-placement algorithm and results are presented as a 2D map of tank-floor sources. The text was submitted by the authors in English.     

An Acoustic-Emission Technique of Forced Vibrations Used for Flaw Detection in Thin-Walled Pressure Vessels

An acoustic-emission technique of forced vibrations based on the principles of the acoustic-topographical integral technique of forced vibrations, combined with the acoustic-emission technique, is considered. An example of using this technique for diagnostics of thin-walled cylindrical shells made of aluminum alloys is considered.__________Translated from Defektoskopiya, Vol. 41, No. 3, 2005, pp. 27–31.Original Russian Text Copyright © 2005 by Popov.     

A source of waves simulating acoustic-emission signals

A source of acoustic waves simulating acoustic-emission signals, a technique for calculating the force acting for a short time on the surface of a tested object, and formulas for calculating the displacement amplitudes for bulk longitudinal and transverse waves excited by this source are proposed. The possibility of calculating the amplitude of the normal component of antisymmetric mode a ₀ of Lamb waves is considered. It is shown that it is desirable to use such a source in acoustic-emission testing of trunk and industrial pipelines of the fuel and energy industry.     

Data-processing algorithms for automatic operation of ultrasonic systems with coherent data processing

Two algorithms for the automatic determination of flaw parameters during ultrasonic testing of welded joints with a high level of structural background noises are considered. The experimental data collected in the course of automated ultrasonic testing (AUT) using Avgur series with coherent processing of data (Avgur 4.2 and Avgur 5 systems) and the results of the assessment of nondestructive testing data are used. The first algorithm is used to identify zones where flaws may be located. This algorithm is applied after running AUT in the search mode. If the parameters of the algorithm application are selected properly, this algorithm makes it possible to determine the coordinates and the conventional length of the identified flaws. The second processing algorithm is intended to determine the flaws actual length and height. For its operations the algorithm uses the images obtained from coherent data processing. Results of testing methods for automatic (computer) determination of flaw parameters are cited. These results are obtained by the Avgur system during testing of austenite welded joints in stainless-steel pipes with a diameter of 325 mm and in perlite-steel pipes of various diameters.Translated from Defektoskopiya, Vol. 40, No. 12, 2004, pp. 3–15.Original Russian Text Copyright © 2004 by Badalyan, Vopilkin, Dolenko, Orlov, Persiantsev.This revised version was published online in April 2005 with a corrected cover date.     

A local method for loading a tested object during acoustic-emission diagnostics

A new acoustic-emission diagnostics method in which there is no need to load an entire structure has been studied. This method of monitoring (as a conventional acoustic-emission method) is based on making a deformation of the tested surface; however in this case, the load is applied to a preliminarily chosen site of the tested object in the most dangerous area.     

Topography of the field of a slot upon nonlinear magnetization

The results of computer simulation of the magnetic field of a slot in a flat plate are presented. The simulation was performed with allowance made for the nonlinearity of the magnetization curve of the plates material. A number of peculiarities of the topography of this field, which are explained by a redistribution of volume magnetic charges over the plate body at different portions of the magnetization curve, were discovered. The simulation was performed for the needs of intrapipe diagnostics and flaw detection.Translated from Defektoskopiya, Vol. 40, No. 10, 2004, pp. 70–78.Original Russian Text Copyright © 2004 by Reutov, Loskutov.     

Quality control of carburized parts made from 15XM steel

A procedure for multiparameteric testing of the depth and hardness of a carburized layer, as well as the hardness of the core of a link bushing made from 15XM steel without the direct access to the cores material, is developed. The testing is based on the relative value of the coercive force that is measured using different schemes of magnetization of a specimen.Translated from Defektoskopiya, Vol. 40, No. 12, 2004, pp. 49–53.Original Russian Text Copyright © 2004 by Kostin, Stashkov, Nichipuruk, Sapozhnikova.This revised version was published online in April 2005 with a corrected cover date.     

Ultrasonic nondestructive testing by head waves: Physical prerequisites and practical use

In 1972, studies on ultrasonic testing of metals from equipment at nuclear power stations performed at TsNIITMASh revealed a phenomenon of excitation of longitudinal waves with angle probes and their further propagation along the contact surface. This phenomenon was further comprehensively studied and called head waves in ultrasonic nondestructive testing of metals. Head waves have found use in practical ultrasonic testing both in Russia and abroad. This paper presents some principal points of the development of the theory and practice of ultrasonic testing by head waves.Translated from Defektoskopiya, Vol. 40, No. 9, 2004, pp. 27–37.Original Russian Text Copyright © 2004 by Razygraev.This paper is based on the materials reported by the author at the International Forum of Specialists of Universities, Research Institutes, and Companies from Different Countries of the World Ultrasonic Nondestructive Testing-75, St. Petersburg, Russia, February 4–5, 2003.     

Combined thermogravimetric and acoustic-emission diagnostics of stages of thermal destruction of substances and materials

The possibilities and limits of existing methods of estimating the thermophysical stability of substances and materials are analyzed. A combined method of thermogravimetric and acoustic-emission (AE) diagnostics of stages of thermal destruction is proposed. It is shown that combination of existing thermal analysis and AE methods leads to an increase in the accuracy and reliability of data on degradation processes in materials under the action of temperature.     

Algorithms,Criteria, and Computing Formulas for Visualization of Acoustic-Emission Sources

This study presents the algorithms, the criteria, and some important computing formulas used for visualization of acoustic-emission sources in tests of pipelines and vessels operated under pressure. These means of visualization also include the instruments for computer processing and presentation of the data on acoustic-emission tests, which can be useful for solving both linear- and planar-source location problems. During analysis of the inspection results of the above-mentioned objects, these facilities were evaluated on the basis of post-processed data that was obtained by various measuring and computing acoustic-emission complexes.__________Translated from Defektoskopiya, Vol. 41, No. 3, 2005, pp. 36–42.Original Russian Text Copyright © 2005 by Shiryaev.     

Universal Waveguide for the Acoustic-Emission Evaluation of High-Temperature Industrial Objects

An original waveguide design has been proposed that makes it possible to carry out acousticemission inspection, diagnostics, and monitoring of industrial objects operating at temperatures above 85°С. The waveguide ensures higher heat-dissipation characteristics, with minimum acoustic losses, than the known clamped-type waveguides. Its application involves no changes to the test object and requires no special permissions from supervising authorities. The underlying physical operating principles, specific features of embodiment, application possibilities, and results of the full cycle of research into how waveguide design features influence heat-dissipation and acoustic characteristics are described. The use of such waveguides widens the application field for the acoustic-emission method as an express technique for evaluating the technical condition of high-temperature objects both during operation and before decommissioning them for technical diagnostics with the aim to identify active (hazardous) areas and include them into the program of testing with other nondestructive methods.     

压力容器氢损伤的监测与检测方法

氢损伤在金属压力容器中是非常普遍的，是石油炼化企业常见的设备破坏形式。介绍了检测氢损伤的主要方法：超声波法、金相法、挂片法、氢传感器探测法和声发射技术，并指出了未来发展的方向，对现场检验具有一定的参考价值。     

A two-coordinate detector for a beam of atomic hydrogen or deuterium

The profile of an atomic beam in the region where it forms is an important characteristic of a polarized atomic hydrogen (or deuterium) source. A mathematical model for a two-coordinate resistive detector of atomic hydrogen beams is presented. Metering equipment and a technique for measuring an atomic beam profile are described, and the results of our measurements are presented.Translated from Pribory i Tekhnika Eksperimenta, No. 1, 2005, pp. 141–145.Original Russian Text Copyright © 2004 by Trofimov, Vasilev, Kovalev, Kravtsov.     

Atmospheric effects of friction,friction noise and wear with silicon and diamond. Part II. SEM tribometry of silicon in vacuum and hydrogen

Scanning electron microscope (SEM) tribometric data on polycrystalline silicon (poly-Si) vs. poly-Si, Si(100) vs. Si(100) and Si(111) vs. Si(111) interfaces, obtained in Torr and in 0.2 Torr partial pressure of hydrogen gas ( ) from room temperature to 850^°C, were performed under standard and much slower thermal ramping rates. The friction data were analyzed per the methodology described in part I of this paper series. The results indicate a highly beneficial friction- and wear-reducing regime within a relatively narrow thermal region. This desirable region coincides with some chemisorption of excited species of molecular hydrogen just before the mass thermal desorption of surface hydrides. These data represent the tribochemical equivalent of a method routinely used in electronics, whereby deep electron traps (dangling Si bonds) are passivated by baking in molecular hydrogen. The also exerts a moderating influence on the size of the friction noise at all test temperatures. However, the general level of friction beyond the beneficial thermal region is high. In parallel, the general wear rate of Si representative of the entire range of standard thermal ramping in both atmospheric environments is in the extremely high 10^-12m³/(N m) range. Operating strictly in the beneficial, low-friction thermal regime resulted in a several orders-of-magnitude reduction in the wear rate over those measured under standard thermal ramping conditions. Although the results confirm previous findings that Si is not a good material of construction for miniaturized moving mechanical assemblies (e.g., microbearings and gears), there seems to be some limited possibility of gas-phase lubrication of Si micromechanisms with rarefied hydrogen at surface temperatures between 100 and 300^°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Atmospheric effects of friction,friction noise and wear with silicon and diamond. Part III. SEM tribometry of polycrystalline diamond in vacuum and hydrogen

In this part III of a multi-part paper series, the results of additional SEM tribometric experiments are described, performed with polished, mostly C(100)-oriented polycrystalline CVD diamond film [PCD_C(100) vs. PCD_C(100)] counterfaces sliding in Torr and in 0.1–0.3 Torr partial pressures of pure hydrogen gas. These tests were completed under a 28 g (0.27 N) normal load, under standard and slow thermal ramping conditions at temperatures ranging from room temperature to 1000^°C. The friction data were examined per the computer logging and analysis techniques described in part I. The treatment of the data is similar to that of Si in part II: the maximum and the average coefficients of friction (MAX.COF and COF) and their ratios (the friction noise FN) are employed to measure possible lubricative interaction of the diamond surfaces with rarefied hydrogen. The results indicate that excited species of molecular hydrogen enter into tribothermally catalyzed reactions not only with Si but with PCD_C(100) surfaces as well. Similar to the behavior of Si, the most beneficial friction-reducing regime occurs in a temperature range just before the thermal desorption of adsorbates. The general magnitudes of MAX.COF, COF and the FN are significantly lower than those of the Si crystallinities, in both vacuum and . The wear rate of the PCD_C(100) film characteristic of the standard thermal ramping test procedure performed mostly in is around , in good agreement with the wear rate previously measured in vacuum for unpolished, fine-cauliflowered diamond films. The data indicate that smooth polycrystalline diamond is a significantly better bearing material for miniaturized moving mechanical assembly applications than Si. This revised version was published online in July 2006 with corrections to the Cover Date.