基于电容成像检测技术的带防腐层金属结构缺陷检测

目的同时检测防腐层下金属结构表面缺陷和防腐层缺陷。方法应用电容成像检测技术同时检测防腐层下金属结构表面缺陷和防腐层缺陷,理论分析防腐层下金属表面减薄缺陷、防腐层下金属表面坑状缺陷和防腐层缺陷对电场线的扰动变化规律,仿真分析这三种缺陷对电势线的扰动变化规律,提出电容成像检测技术用于检测防腐层下金属结构表面缺陷和防腐层缺陷的可行性,并搭建电容成像检测系统,利用检测系统检测2 mm和4 mm防腐层下金属表面减薄1 mm和2 mm缺陷、金属表面坑状缺陷、2 mm防腐层下金属结构(防腐层含有通孔缺陷)。结果理论分析和仿真分析显示,电容成像检测技术具有检测防腐层下金属结构表面缺陷和防腐层缺陷的可行性。试验结果表明,电容成像系统能检测2 mm和4 mm防腐层下金属表面减薄1 mm和2 mm缺陷、金属表面坑状缺陷、2 mm防腐层下金属结构(防腐层含有通孔缺陷)。除此之外,在防腐层下金属表面缺陷处的检测结果值呈现上升的趋势,在防腐层缺陷处的检测结果呈现下降的趋势,据此规律可以区分防腐层下金属表面缺陷和防腐层缺陷。结论电容成像检测技术能检测防腐层下金属结构表面减薄缺陷和坑状缺陷,还能同时检测防腐层本身存在的缺陷。根据检测在防腐层下金属结构表面缺陷和防腐层缺陷所呈现的不同结果,可用于区分这两类缺陷,有利于为油气储运设施缺陷维修制定合理的方案。

Defect Detection of Metal Structure with Anticorrosive Coating Based on Capacitive Imaging Technology

Objective To detect defects of metal structure with anticorrosive coating and defects of anticorrosive coating at the same time. Methods Capacitive imaging detection technique was used to detect defects of metal structure with anticorrosive coating and defects of anticorrosive coating at the same time. The variation of the electric field line under defects of metal structure with anticorrosive coating and defects of anticorrosive coating was analyzed theoretically, and the variation of the electric potential line under defects of metal structure with anticorrosive coating and defects of anticorrosive coating was analyzed by simulation. The feasibility of using capacitive imaging detection technique to detect defects of metal structure with anticorrosive coating and defects of anticorrosive coating was discussed. A capacitive imaging detection system was constructed to detect defects of 1 mm and 2 mm on the metal surface under 2 mm and 4mm anticorrosive coating, the pit surface defects on the metal surface under the anticorrosive layer of 2 mm and 4 mm, and the metal structure under the 2 mm anticorrosion coating (including the through hole defect in the anticorrosive layer). Results Theoretical analysis and simulation analysis showed that the capacitive imaging technology had the feasibility of detecting the surface defects of metal structure with the anticorrosion coating and defects of anticorrosive coating. The test results showed that capacitive imaging technique could detect defects of metal structure with anticorrosive coating and defects of 1 mm and 2 mm on the metal surface under 2mm and 4mm anticorrosive coating, the pit surface defects on the metal surface under the anticorrosive layer of 2 mm and 4 mm, and the metal structure under the 2 mm anticorrosion coating (including the through hole defect in the anticorrosive layer). In addition, the detection results of the metal surface defects with the anticorrosion layer showed a rising trend, and the detection results in defects of the anticorrosion layer showed a downward trend. According to this rule, defects of metal structure with anticorrosive coating and defects of anticorrosive coating could be distinguished. Conclusion The capacitive imaging detection technology can detect the surface thinning defects and pits defects of the metal structure under anticorrosion and defects of the anticorrosion layer itself at the same time. According to the different results of the metal structure surface defect and the anticorrosion layer defect under the anticorrosion layer, the detection results can be used to distinguish these two kinds of defects. It is favorable for developing reasonable plans for repair of defects of petroleum storage and transportation facilities.