College - Author 1
College of Engineering
Department - Author 1
Materials Engineering Department
Degree Name - Author 1
BS in Materials Engineering
College - Author 2
College of Engineering
Department - Author 2
Materials Engineering Department
Degree - Author 2
BS in Materials Engineering
Date
6-2021
Primary Advisor
Trevor Harding, College of Engineering, Materials Engineering Department
Abstract/Summary
Oxygen corrosion is a major threat to seawater injection systems that are part of offshore drilling operations. Seawater is typically deoxygenated to an industry standard of(DO) by injection through a deaeration column followed by treatment with oxygen scavenging chemicals. Commercial simulation software like OLI Studio: Corrosion Analyzer predicts high corrosion rates when injection seawater contains high DO levels, justifying deoxygenation. However, a notable lack of experimental data exists concerning the effect of varying levels of dissolved oxygen on corrosion rate. The goal of this project is to measure the effect of three dissolved oxygen levels (0, 62, and 620 ppb) on the corrosion rate of 1018 and 410 steels for comparison to predictions made by OLI Studio: Corrosion Analyzer. Corrosion immersion testing was performed on quadruplicate specimens for 24 hours according to ASTM standards. Corrosion rates based on gravimetric mass loss measurements after removal of corrosion products were then computed and compared to simulation results. Microscopy of the specimens confirmed that significant localized corrosion occurs near crevices, and uniform corrosion in the form of rusting occurs on the surfaces of the coupons at higher dissolved oxygen concentrations. OLI Studio demonstrated similarities to experimental corrosion rates: increasing dissolved oxygen in seawater resulted in an increase in corrosion rates for carbon steel and a negligible change in corrosion rates for stainless steel. Corrosion rates for both alloys even at elevated levels of 620 ppb dissolved oxygen were below the typical corrosion design tolerance of 4 mpy consistent with simulation results.
URL: https://digitalcommons.calpoly.edu/matesp/239