带钢制保护套管的钢管腐蚀缺陷的脉冲涡流检测方法研究

流体输运钢管外部加一层保护性钢套管，会使从外部检测内管腐蚀更加困难。本研究基于脉冲涡流检测技术，设计一种扁平U型结构传感器，可在双层钢管间隙中检测内管腐蚀情况而不受套管影响，且该检测方法一次扫查可同时获得内管的内壁和外壁减薄信息。使用圆柱型探头和U型探头检测试件3处缺陷，同时将钢管间隙减小到25、35 mm，与不加套管时的检测缺陷结果进行对比。结果表明:和传统同轴式圆柱形探头相比，U型传感器对外部保护钢管有着较强的抗干扰的能力，对衰减曲线影响较小，在间隙间检测内管腐蚀缺陷有较高的灵敏度，能够满足工业现场要求。

Corrosion Detection in Steel Pipes With Steel Casing Pipes Using Pulsed Eddy Current Method

In some industrial applications, a protective steel casing is added to the outside of the pipe for fluid transport, which makes it more difficult to detect corrosion of the inner pipe from the outside. Based on the pulsed eddy current testing technology, a flat u-shaped structure sensor is designed in this paper, which can detect the corrosion of the inner tube in the gap of the double-layer steel pipe without being affected by the casing. Moreover, this detection method can obtain the thinning information of the inner and outer wall of the inner tube through a single scan. In this paper, cylindrical probe and u-type probe were used to detect three defects of the specimen, and meanwhile, the gap between steel tubes was reduced to 25 mm and 35 mm, and the detection results were compared with those without casing. The results show that compared with the traditional coaxial cylindrical probe, the u-type sensor has stronger anti-interference ability to the external protection steel pipe, less influence on the attenuation curve, and higher sensitivity to detect the inner pipe between gaps, which can meet the demand of field detection.