Practically any welded joint cannot be considered as a homogeneous isotropic medium for control by ultrasonic (ultrasonic) waves. If the phase changes during the propagation of the ultrasonic wave are less than 180 degrees, then the medium can be considered as isotropic and homogeneous. Otherwise, restoring the image of the reflectors using simple algorithms will cause the glare of the reflectors to shift from their true positions, and the shape of the glare will be distorted. Moreover, distortions can lead to the fact that instead of one glare, two or more with a smaller amplitude will appear. As a result, the glare amplitude of the large reflector may not reach the rejection level and the defect will be missed. One of such objects is repair welding in welded joints of pipelines DN800, which have anisotropy. The situation is complicated by the presence of anticorrosive surfacing on the inner surface of the pipe, which also has pronounced anisotropic properties, which does not allow working on a single reflected beam, without taking into account its anisotropic properties.
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.
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.
At the round table dedicated to the use of phased arrays in the framework of the exhibition-conference Territory NDT 2019 a report summarizing successful examples of the introduction of flaw detection for the control of welded joints and base metal using phased array technologies and digital antenna focusing is made. Further ways of improving these technologies are outlined.