在役高温蒸汽管道母材内壁裂纹超声检测分析

Ultrasonic Inspection and Analysis of Cracks in the Base Metal of in Service High Temperature Steam Pipe

某热电厂在役高温蒸汽管道对接焊缝超声检测时,发现焊缝附近的母材内壁存在整圈回波信号。为了分析该信号是否为缺陷回波,针对该回波信号的特征提出了4种假设,并利用多种规格的探头在不同位置进行扫查。结合所有扫查结果和检测数据,从理论上分析了各种假设的可能性,排除不成立的假设。最终判定该信号为弯头侧母材内壁裂纹端角反射回波,并通过打磨验证的方式证实了该裂纹的存在。

During the ultrasonic testing of butt weld of high temperature steam pipe in service in a thermal power plant,it was found that there was a whole circle echo signal in the inner wall of base metal near the weld.In order to analyze whether the signal is defect echo,four hypotheses are put forward according to the characteristics of the echo signal,and a variety of probes are used to scan at different positions.Combined with all the scanning results and test data,the possibility of various hypotheses is analyzed theoretically,and the false hypothesis is excluded.Finally,it was determined that the signal was the reflection echo from the crack tip angle of the inner wall of the base metal on the elbow side,and the existence of the crack was confirmed by grinding verification.