Academic publications on the CO2 corrosion of carbon steel linepipes in oil and gas production environments date back as far as the 1940s. Despite considerable research, CO2 corrosion and preferential weld corrosion still account for approximately 46% of material failures within the oil and gas industry, and present a serious risk to asset integrity and reliability. The problem of preferential CO2 weld corrosion is complicated by the formation of siderite based corrosion product layers, which can either inhibit or accelerate localized corrosion. Longitudinally welded ERW (electric resistance welded) linepipe is a commonly used material for oil and gas pipelines, due to its lower cost and shorter lead times over seamless. However, the longitudinal ERW weld introduces a region of microstructural heterogeneity, which sometimes is susceptible to localized CO2 preferential weld corrosion. Pipelines are often made from ERW linepipes of the same material grade (e.g. API grade X42), however, sourced from several manufactures. Despite having nearly identical mechanical and chemical properties, after a relatively short period of operation (several months to a couple of years), some manufacturers appear to have a significantly higher susceptibility to CO2 preferential weld corrosion than others. The reason for this difference in susceptibility is unclear. Furthermore, unlike for H2S environments, there is no standard regarding material selection to avoid preferential weld corrosion in CO2 environments. The oil and gas industry therefore requires: 1. An explanation as to why relatively similar ERW carbon steel linepipes can have significantly different susceptibilities to CO2 preferential weld corrosion. 2. An experimental test method that can quantitatively identify a particular linepipes susceptibility to CO2 preferential weld corrosion, so various manufacturers can be compared during the material selection process of a project. This thesis developed a new methodology for assessing an ERW linepipes susceptibility to CO2 preferential weld corrosion. The new approach is referred to as multi-channel zero resistance ammetry. The developed technology allowed the ERW materials to corrode in a natural and unforced way in various CO2 environments inside a stirring autoclave, however, the galvanic coupling currents flowing between different microstructural zones present in the ERW material could be monitored in real time. This allowed the direct identification of microstructural zones (and therefore specific linepipes) that were susceptible to CO2 preferential weld corrosion. Scanning electron microscopy was able to correlate localized corrosion susceptibility to corrosion product layer morphology around the weld region, which was dependent on the cementite morphology in the steel. From this, a model was developed explaining how ERW welds corrode, and why some ERW linepipes are more susceptible to CO2 preferential weld corrosion than others, despite being the same material grade. The information from these experiments provides oil and gas companies with material selection guidelines for avoiding preferential weld corrosion of ERW linepipe in CO2 production environments. The developed technology also has the potential for field deployment, where the effects of changes in operating conditions (i.e. inhibitor concentration, pH, flow rate) to weld corrosion behaviour can be viewed immediately. Fundamentally, results from this thesis can be used as a guide to increase asset integrity and reliability.