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

Abstract 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 CO 2 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 FeCO 3 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.