燃气管道腐蚀缺陷电磁超声检测方法

Electromagnetic Acoustic Transducer on Corrosion Detection of Gas Pipeline

电磁超声可用于燃气管道的内检测,但外部的腐蚀缺陷会影响厚度检测。为了研究腐蚀形成的斜面缺陷对电磁超声测厚的影响,分析了横波在斜面试件中传播和反射,发现使用横波电磁超声换能器进行斜面测量中误差产生的原因为横波的到时差异,并用基于COMSOL的有限元模型对换能和测厚过程/进行仿真,最后通过缺陷钢板的实验验证分析的结论。研究发现在小倾角的斜面缺陷情况下,测得厚度偏大;斜面越陡,误差越大。

Electromagnetic Acoustic Transducer(EMAT) could be used in inner inspection for gas pipeline,but the thickness measurement could be interfered by the corrosion defects on the outer surface.In order to study the influence of corrosion defects on EMAT testing,the transmission and reflection of shear waves in slope specimen was analyzed.It was found out that the difference of arrival time was the cause of inaccuracy in slope thickness measurement using bulk-wave EMAT.Then a finite element model based on COMSOL was used to simulate the transduction and measurement process.At last,experiment on steel plate with defects was conducted for validation.It was found out that in condition of small angle of inclination,the measured thickness tend to be larger than the actual,and the error increases as the angle grows.