The creation of automated recognition systems for reflectors based on images obtained by ultrasonic antenna arrays is a very urgent task. Its solution will increase the speed of preparation of control protocols and increase their reliability by reducing the influence of the human factor.
In the practice of ultrasonic testing, there are objects whose thickness is more than 200 mm or objects whose control is carried out on rays repeatedly reflected from its boundaries. Such objects include reactor vessels of nuclear power plants, main shut-off valves (GPP), welded joints of rotors, tees of gas pipelines, etc.
Two methods of ultrasonic thickness measurement, developed by the ECHOPLUS Company, are considered, one of which is designed for continuous thickness measurement of the base metal (SLT), the other for thickness measurement of welded joints. The ultrasound methods used in these techniques are briefly described. The results of their application are presented. Also described are the controls manufactured by the ECHOPLUS Company for thickness measurement according to these methods.
The advantages of using 32-channel flaw detectors in comparison with 16-channel ones are analyzed. Numerical experiments have demonstrated that the frontal resolution of the image is higher when using 32 elements. At large thicknesses, it is better to work with a 32-element grid, since the near zone is larger. The use of antenna arrays is more efficient for 32 channels (8 by 4), since it is possible to increase the frontal resolution along the seam axis. The presence of 32 channels in the flaw detector makes it possible to use two 16-element antenna arrays to the left and right of the seam to obtain a combined image via N-, P- and NP-channels. The larger grip of the 32-element array makes it possible to carry out continuous thickness measurement faster compared to using an antenna array of 16 elements.
The report describes the advantages and features of using flaw detectors with the support of phased arrays (FR) and the diffraction-time method (TOFD), such as AUGUR-ART2020 and AUGUR-TF, provides practical examples of the use of technologies for the control of welds, thickness measurement, control of objects not previously controlled by ultrasound, describes the features of the software used.
Examples of the application of modern technologies related to the industrial revolution 4.0 in ultrasound control, implemented or planned for implementation in the products of the ECHOPLUS: AUGUR software, hardware implementation, algorithms are considered.
The report presents modern means of control of welds and base metal with the use of FR and TOFD. The main features of such equipment: 1) Data recording with an encoder and subsequent storage in a database. 2) Measuring the height and extent of defects -> norms and application of a risk-based approach. 3) Monitoring of the condition during operation. Examples are given from the practice of replacing the RGC with a narrow one during the construction and operation of the OPO, as well as examples of the use of the ECHOPLUS equipment.
When conducting ultrasonic testing using antenna arrays, interference pulses may be present in the measured echo signals, which, after the image of the reflectors is restored, may form false glare that complicates image analysis. Such undesirable pulses include pulses of reverberation interference that occur when the probing pulse is reflected from the prism boundaries, and/or pulses reflected from the structural reflector of the object of control. The simplest way to reduce the amplitude of such pulses, in case of their high stability from measurement to measurement, is to subtract a pattern with interference pulses from the measured echo signals. However, if the interference pulses change slightly during ultrasonic testing, slightly changing the arrival time and amplitude, then their suppression by subtracting the noise pattern will not be effective. To reduce the level of weakly varying interference, it is proposed to apply the decorrelation procedure.
The principle of operation is described and the possibilities of quality control of welded joints using a set of automated visual and measuring control tools based on a laser triangulation sensor are analyzed. The advantages of using this equipment as part of the AUGUR-TF automated ultrasound control system are described.
The surface of the control objects may be uneven due to its design features. After installation, during operation or preparation for control, the initially flat surface of the object of control may lose this property. Many methods of image reconstruction of reflectors using ultrasonic antenna arrays proceed from the fact that the surface of the object of control is a straight line. Currently, in the practice of ultrasonic monitoring, the method of digital focusing of the antenna array (CFA) is widely used, which involves recording echo signals during radiation and reception by all pairs of the antenna array and restoring the image of reflectors from the measured echo signals by the combined SAFT (C-SAFT) method. If the antenna array scans along the X axis, then by adding together the CFA images obtained for each position of the antenna array, it is possible to obtain a final image with a lower noise level and a higher frontal resolution.