Transverse cracks ultrasonic discrimination

Transverse cracks ultrasonic discrimination of LSAW steel pipe

When applying the above " parallel scanning with a weld reinforcement" method for detecting transverse weld defects, if found to have reflected signal, can polish the weld reinforcement up, and further measure and reference plane defects, depth position, defect height, the reflection characteristics of each defect, defect orientation, defect waveform, dynamic waveform, echo envelope parameters, combined with groove form, material properties, welding technology and welding methods such as a comprehensive judgment, as far as possible confirm the actual nature of the transverse defects, and to determine the location of the defect. Then gouging grinding anatomy, and then verify with the magnetic particle testing. In the detection process, discrimination steps of transverse cracks for LSAW steel pipe are as follows:

(1) At first, under a transverse scanning sensitivity (in this case increase 6 ~ 12 dB compared to the vertical scanning sensitivity) probe on the welds do direct parallel scanning;

(2) After the transverse defects displayed, select 1 to 2 high amplitude echoes position, and grinding flush the weld reinforcement for analysis, reflection amplitude is lower than 20C shown, in principle, no qualitatively;

(3) Surrounding scanning to determine whether is a point-like defect, if is, the point-like defect is with not further characterization;

(4) Through the observation of the static wave and dynamic wave forms, and the analysis of the defect signal amplitude change to determine the transverse cracks. There are four basic ways of probe movement that move around, move back and forth, fixed rotation and orbital motion, corresponding to the dynamic wave also four forms.