Experimental study on non-uniform corrosion of elbow-to-pipe weldment using multiple ring form electrical resistance sensor array

• Published in: Measurement : journal of the International Measurement Confederation 2019-05, Vol.138, p.8-24
• Main Authors: Zhu, Yesen, Xu, Yunze, Li, Ketian, Wang, Xiaona, Liu, Gang, Huang, Yi
• Format: Article
• Language: English
• Subjects: Base metal; Chemical composition; Computational fluid dynamics; Computer simulation; Corrosion; Corrosion resistance; Corrosion tests; Elbow-to-pipe weldment; Electric resistance; Electrical resistance; Fluid dynamics; Heat affected zone; Iron carbonate; Multiple rings array; Non-uniform corrosion; Organic chemistry; Pipe joints; Pipes; Protective coatings; Protective film; Sensor arrays; Surface properties; Uniform attack (corrosion); Wall shear stresses; Welded joints; Welding
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2019.02.035

•A sensor system based on multiple ring form electrical resistance array was developed.•The non-uniform corrosion around the pipe circle of the elbow-to-pipe weldment was studied.•The influence of the temperature and metal microstructure on the formation of FeCO3 film was studied.•Top of line corrosion induced by the condensed water droplet was probed by the sensor system. A corrosion monitoring system was designed and fabricated to study the non-uniform corrosion of elbow-to-pipe weldment using a multiple ring form electrical resistance sensor array. The corrosion behaviour of the different areas of the weldment, i.e. base metal (BM), heat affected zone (HAZ) and welding metal (WM) were studied under different fluid temperatures using the multiple rings array. In conjunction with electrochemical measurements and surface characterization, it is found that a dense protective film could form on the steel surface in the saturated CO2 fluid when the solution temperature was above 60 °C with a pH of 6.6. The specific microstructure and different chemical composition at welding area might delay the precipitation of the FeCO3 crystal. The initiation of top of line corrosion due to the condensed droplet was probed by the sensor system with the fluid temperature increased to 50 °C. Through the computational fluid dynamics (CFD) simulation results, it can be found that highly corroded areas are always suffering higher wall shear stresses.