焊管常用探伤方法及技术

Commonly-used NDT Methods and Techniques for Weld Pipes

介绍了焊管常用的3种探伤方法(漏磁探伤、涡流探伤和超声波探伤)及技术。分析了3种探伤方法的优缺点:漏磁探伤灵敏度高,能很好地分辨出焊管内外壁缺陷,但长管体、大壁厚管在漏磁探伤后需做消磁处理;涡流探伤检测速度快,但受趋肤效应的限制,很难发现工件深处的缺陷;超声波探伤穿透能力强、缺陷定位准确、成本低、速度快,但探伤操作需经耦合,在北方严冬环境下耦合时焊管易冻结,给探伤作业带来不便。

Described in the paper are the three commonly-used NDT methods and techniques for weld pipe flaw inspection, i.e., the MFL detection, the eddy-current detection and the ultrasonic detection. Also analyzed are the advantages and disadvantages of these methods. The MFL method features high sensitivity which ensures satisfactory identification of both outer and inner flaws of the pipe, but in case of long large-sized heavy-wall pipe, demagnetization is necessary to be carried out upon ending of the detection. As for the eddy-current method, although the detection speed is rather high, it is so difficult to find out any flaw located deep in the workpiece due to the Kelvin skin effect. And speaking of the ultrasonic method, the advantages are high penetrating force, high flaw-positioning accuracy, low operation cost, and high detection velocity, but medium coupling is needed for the detection, which may cause, in winter, the trouble of freezing of the pipe, particularly in hi- latitude areas, thus make it rather difficult to keep the detection operation going smoothly.