Ultrasonic Testing of DSAW Pipe

In the ultrasonic detection of DSAW tube, how to identify and determine echo is a key issue. By analyzing the actual ultrasonic detection characteristics of double sided submerged arc welded pipe, the influence of ultrasonic defect signal or non defect signal and the influence of the radius of curvature of steel tube on the defect position are analyzed, including isolation, inclusions of ultrasonic echo signal, crack and base metal stratification. In this paper, the causes and identification methods of four kinds of false defect waves are summarized, such as the reflection wave of the coupling mixture, the reflection wave on the weld surface, the reflection wave caused by the upper and lower dislocation on the weld, and the accuracy of the defective ripple recognition of the defect free wave formed by the weld height or the bottom cut. It provides a new idea and a new direction for the actual ultrasonic detection of the DSAW pipeline.


In the ultrasonic inspection of the weld of the steel tube, because of the characteristics of the steel pipe welding process, there are often some other false defect echoes except the initial wave and the defect wave, and these false defect wave interference defects. The following are the causes and identification methods of producing four kinds of false defects.
(1) reflection wave of coupling agent
Theoretically, the thickness of the coupling layer is an integral multiple of the radius. The coupling agent is too thick and the fluidity is not good; the thickness of the coupling layer is too thick to accumulate in the front of the detector, and a part of the P-wave reflected from the piezoelectric wafer is converted to the surface wave, which causes the reflection signal. In the coupling agent, the wave will disappear.