The results of studying the effect of cyclic loading according to the zero-tension scheme with an amplitude approximately corresponding to the conditional yield strength on the magnetic and acoustic parameters of hot-rolled pipe steel 08G2B, including the longitudinal and transverse sound velocities, are presented. An AUGUR-ART flaw detector and a technique developed by the ECHOPLUS Company were used to determine the speed of sound without an etalon. The parameters that uniquely change with an increase in the number of loading cycles are determined, which makes it possible in principle to use them for the development of non-destructive methods for monitoring fatigue degradation of the material of structures made of the studied steel.
The report on UZDM-2019 made a general analysis of the technologies of narrowly inaccessible (problematic) welded joints, such as: austenitic welds, seams welded into a narrow section, branch pipe welds, seams with limited access to accommodate piezoelectric converters.
All these tasks are solved using AUGUR series systems developed and manufactured by the ECHOPLUS Company.
The presentation describes the main difficulties and ways to solve them during ultrasonic inspection of welded joints of welding pipes, flanges and bosses and welding. The possibility of using the technology of phased antenna arrays for narrowly specified welds is shown. The reliability of the control is achieved by selecting the parameters of the phased array and the scanning zone, building a three-dimensional model of the object of control. This technology can be implemented using AUGUR-ART or GEKKO flaw detectors.
The article discusses modern methods of automated ultrasonic inspection of welded joints of main gas pipelines. Among these methods, the most powerful are high-tech methods using coherent methods of processing ultrasonic echo signals. They allow solving a wide range of practical tasks, from detecting small defects against the background of structural interference of metal to diffraction flaw detection in thick-walled control objects. Thus, the implementation of the three-dimensional method of coherent image reconstruction made it possible to completely solve the problem of controlling the under-lining welded joint of welded tees with overlays. The task is complicated by the limited access to the welded joint, as well as the presence of the influence of the welded joints of the lining in the control area. It is impossible to solve the problem at the required level of sensitivity by traditional methods. The article discusses the main provisions of the technology of automated control of such objects, the main results of certification and practical tests. The use of a combination of different methods for obtaining visual data allowed us to combine productivity, high quality and complete documentation of control. An example of such a combination is the new AUGUR-TF system, which successfully passed certification tests at VNIIGAZ in 2017. The system uses methods of antenna array phasing, multi-zone control according to the tandem scheme, the diffraction-time method, as well as the method of digital focusing of the antenna. During the control process, the first three methods are used simultaneously, while maintaining a high scanning speed.
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.
The general principles of construction are described and the features of methods of automated ultrasonic inspection of welded joints using systems with coherent processing using the methodology of synthesized aperture are analyzed. The features of the application of devices using digital SAFT and CFA processing (SAFT and CFA flaw detectors) and devices with headlights (HEADLIGHT flaw detectors) are analyzed. A common characteristic of flaw detectors is to obtain a high-resolution image of the controlled volume of the product. The actual parameters of the detected discontinuities are estimated from these images. The methods of AUZK developed by LLC "SPC thr ECHOPLUS, which allow using the useful features of SAFT, FAR and CFA flaw detectors, are considered. All control methods are divided into two groups: control of pearlitic welded joints and welded joints with a high level of structural noise. The features of the development of methods depending on the object of control are considered. Examples of practical use of techniques are given. Their main characteristics are given, such as: operating frequency, methods of coherent data processing, resolution and measurement error of real dimensions, etc.
Quantitative assessment of the reliability of non–destructive testing systems is an important factor in a risk-based approach to diagnostics. For this purpose, defect detection curves (PoD curves) and confidence curves (ROC curves) are usually used for non–destructive testing (NC). The PoD (Probability of Detection) curve describes the probability distribution of detecting defects by their size. This curve reflects the capabilities of the used method and monitoring equipment on the selected sensitivity of the system and allows you to predict the detectability of defects of various sizes in the object due to the known functional dependence of the probability of detecting defects on their size.
To assess the reliability of the data obtained during the control of an object using methods and means of ultrasonic inspection (ultrasound), it is necessary to take into account not only the probability of detecting defects during control, but also the probability of their skipping and fixing false defects. For these purposes, ROC diagrams and ROC curves (Receiver Operating Characteristic curve) are often used, which reflect the mutual dependence of the number of false and correctly found defects. The actions performed for their structure are called ROC analysis. ROC analysis was developed and applied in the theory of signal processing and radar to describe the relationship between events of correct target detection and false positives. In non–destructive testing, ROC analysis began to be used to analyze the reliability of the control of techniques, equipment and personnel as a means for a quick assessment of methods and devices of ultrasonic testing. Below we will consider the features of the application of ROC analysis for ultrasonic flaw detection and ultrasonic flaw detection devices. To do this, we use a database of UZK obtained on austenitic annular welded joints (SS) containing cracks of various heights. The measurements were performed using two methods of ultrasonic flaw detection (FAR and SAFT processing), in which the analysis of control data was performed using acoustic focused images, and the traditional method of ultrasonic flaw detection, in which the analysis of control data was performed by the amplitude of the ultrasonic signal.
The article deals with the application of automated ultrasonic inspection of austenitic welded joints, performed instead of radiographic control carried out during the installation of technological pipelines of the catalytic cracking complex. The results of tests of the automated ultrasonic inspection of austenitic welded joints based on the use of coherent methods for obtaining acoustic images of the internal structure of the object of control are presented.
The report considers the possibility of switching from the old criteria for assessing the quality of welded joints, such as equivalent area, number of point defects, conditional dimensions, etc., to new information criteria for defects based on the results of modern types of automated ultrasonic testing. Three-dimensional visualization of control areas obtained using modern coherent image reconstruction methods provides new information parameters. Such parameters can be the overall dimensions of defects, the profile of the inner surface of the seam, as well as a visual, close to optical, image of the defect obtained by using many sounding schemes using digital focusing technology of antenna arrays. Examples of existing methods with dimensional criteria according to the new standards of quality assessment are given.