In an interview with the Newspaper.ru we talk about our main achievements and plans
Tests of flaw detectors with phased arrays for the control of welded joints of bridge metal structures were carried out in the ECHOPLUS Company. Gekko and AUGUR-ART flaw detectors were used on butt, T-bar welded joints and contact welding joints of Nelson stops. The use of phased arrays in the digital focusing mode of the antenna in combination with scanning devices made it possible to identify defects at the required sensitivity level, to ensure 100% data recording.
The tests were carried out at the Bovanenkovsky NGCM of Gazprom Dobycha Nadym LLC. To solve the problem of continuous thickness measurement, a GECKO phased array flaw detector and a Chameleon two-coordinate scanner were used. The possibility of detecting corrosion (0.5 - 1 mm) in field gas pipelines is shown. The measurements were carried out in laboratory conditions and at a temperature of minus 17 degrees.
It is proposed to use the maximum entropy (MME) method to reconstruct the image of reflectors from echo signals measured in the TOFD mode in order to increase the accuracy of determining the size of the discontinuities of the control object. The calculation of the echo signal reflected from a point reflector at an arbitrary depth in the TOFD mode was carried out. For verification, the results obtained in numerical modeling were compared with the results of calculating a similar model using the CIVA program. Using the example of images obtained in numerical and model experiments, the influence of the factor of changing the shape of echo signals on the results of the ME method is studied. As the study showed, the variable waveform imposes a restriction on the use of this super-resolution method, which was the reason for the subsequent modification of the image recovery algorithm by the ME method. This modification made it possible to visualize inhomogeneities in the material of the object of control more qualitatively.
For the calculation of echo signals during numerical experiments of ultrasound control, the finite difference method in the time domain (CRVO) can be used. Since the KRVO method is based on an explicit numerical solution of the wave equation for an elastic medium, it takes into account such effects as the occurrence of a run-around wave on a volumetric reflector, the effects of the transformation of a longitudinal wave into a side wave when ultrasound is scattered on a crack, the scattering of pulses between reflectors and the boundaries of the object of control. The numerical solution of the vector wave equation by the KRVO method, in contrast to the modeling methods based on the theory of ray tubes, allows you to more accurately simulate the results of ultrasonic testing. The article considers three solutions to the problem of suppressing the reflection of pulses from the boundaries of the computational grid. Calculation of the direct problem of propagation of elastic vibrations in a solid by the KRVO method may be useful for solving the coefficient inverse problem of ultrasonic non-destructive testing.
To develop methods of ultrasonic inspection of such complex objects as composite seams, the method of finite differences in the time domain (CRVO) can be used to calculate echo signals in numerical experiments. Since the KRVO method is based on an explicit numerical solution of the wave equation for an elastic medium, it takes into account such effects as the occurrence of a run-around wave on a volumetric reflector, the effects of the transformation of a longitudinal wave into a side wave when ultrasound is scattered on a crack, the scattering of pulses between reflectors and the boundaries of the object of control. The application of the KRVO method for modeling the propagation of ultrasound in a sample with high structural noise and in samples of anisotropic inhomogeneous materials is justified. Calculation of the direct problem of propagation of elastic vibrations in a solid by the KRVO method may be useful for solving the coefficient inverse problem of ultrasonic non-destructive testing.
The article proposes a method for determining the velocity of a longitudinal ultrasonic wave in a homogeneous welded joint, based on a comparison of measured and calculated echo signals reflected from the bottom of the control object using two antenna arrays on prisms operating in double scanning mode. The influence of errors in setting parameters such as the distance between antenna arrays, the thickness of the control object and others on the accuracy of calculating the wave velocity in a welded joint is analyzed. The results of numerical and model experiments on the calculation of the wave velocity in a welded joint are presented. Using the developed method in the model experiment, it was possible to measure the velocity of the longitudinal wave in the welded joint model with an error of less than 0.7%. The proposed method can be used to find the initial approximation in the nonlinear inverse problem of tomographic diagnostics of welded joints in the wave approximation
The report presents information on the development and pilot operation of an automated ultrasonic control system with a full automation cycle based on phased antenna arrays together with the ultrasonic inspection technique of annular welded joints of steam generator shells PGV-1000, PGV-1000M. Information about automation algorithms and their results are given work on real welded joints containing permissible discontinuities and on test samples containing unacceptable discontinuities. All stages of automation at the stages of setting up, collecting and analyzing ultrasound control data are shown.
Based on the analysis of the results obtained during the implementation of the pilot operation program, it was found that the use of the system and methodology for operational control of NPP equipment and pipelines is justified.