New Trends in Ultrasonic Testing of Flash Butt Welded Joints

Abstract—The advantages of using flash butt welding for large-diameter pipes in the construction of main pipelines for various purposes, including the high productivity of this technology, are noted. However, one of the main factors limiting the use of this welding method in pipeline construction practice is the lack (until recently) of nondestructive testing methods capable of reliable detection of some defects, which appear during its application. Primarily, this refers to vertically oriented oxide films of various structures and configurations in the cross section of the weld. Recent studies have shown that the best results in detecting such defects can be achieved by combining diffraction and echo ultrasonic testing methods. To solve this problem, we analyze the capabilities of various ultrasonic testing methods applicable to welds of the given type. However, this type of flaw detection encounters some limitations, since the mentioned weld defects are semitransparent to ultrasonic waves. Therefore, additional possibilities of several atypical versions of mirror–shadow and echo ultrasonic testing methods are considered. The first of the methods examined in detail takes into account the structural features of the welds made by flash butt welding to verify their quality. The second method can be used to reliably detect a defect with a low ultrasonic wave reflectivity located in the fusion plane. The importance of continuing investigations into the capabilities of the methods under study and collecting statistical data to determine the reliability of the technologies based on their use is noted.