Development of an elbow for erosion and erosion-corrosion analysis of X65 carbon steel

摘要

Erosion-corrosion is a significant problem in the oil and gas industry that can cause high rates of wear of carbon steel pipelines. When sand particles are present in the produced fluids, wear rates of carbon steel can increase significantly, resulting in wear of the pipeline caused by sand particle impacts in addition to carbon dioxide (CO_2) corrosion. Erosion-corrosion can be complicated further by the combined effects of erosion and corrosion whereby erosion enhances the corrosion wear and corrosion enhances the erosion wear, with the total erosion-corrosion degradation being equal to the sum of each individual component (corrosion, erosion, corrosion-enhanced erosion and erosion-enhanced corrosion). In pipeline components, such as an elbow, the rates of wear due to erosion-corrosion can be much more significant than in straight sections of pipe. This work presents the development of an elbow component that enables erosion and erosion-corrosion at different impact angles to be quantified. Results are presented for tests completed to determine erosion-corrosion rates of several X65 samples located at different angles on the inner and outer radius of the elbow. Three types of test were completed to determine the contribution of each individual wear component to the total erosion-corrosion wear rate - (1) flow induced corrosion tests in a CO_2 saturated solution with no sand particles, (2) erosion tests in a nitrogen (N_2) saturated solution and (3) erosion-corrosion tests in a CO_2 saturated solution with sand particles present in the flow. Degradation rates of the X65 samples in the elbow were measured using various techniques, including mass loss and electrochemistry. Results are presented from each of these tests showing the contribution of corrosion, erosion, erosion-enhanced corrosion and corrosion-enhanced corrosion to the total erosion-corrosion degradation rate at multiple locations in the elbow.