With continuous exploitation of oil and gas in deepwater, more and more stainless steels and Ni-based alloys has been used in subsea production system, such as manifold, well jumpers, umbilical and flange. Subsea installation is at high risk of crevice corrosion because of raw seawater ingress during tie-in operations and existence of crevice at the flange interface. Stainless steels are susceptible to crevice corrosion, and based on this corrosion risk, effect of temperature (4oC, 20oC and 60oC) on initiation and propagation of crevice corrosion of three kinds of stainless steels (AISI 316L, UNS S31803 and UNS S32750) is studied in this article. Crevice corrosion susceptibility of stainless steels is studied by cyclic voltammetry, and corrosion morphology is observed by SEM. Corrosion production is analyzed by EDS. The initiation and propagative orientation of crevice corrosion is analyzed at low temperature. The results show that UNS S32750 has a longest initial time of crevice corrosion, and it has highest crevice corrosion resistance.
Due to the worldwide demand for oil and gas, the exploitation has been expanded to deepwater. Stainless steels have been widely used in oil and gas field as their excellent corrosion resistance in chlorinated seawater, such as manifold, well jumpers, umbilical and flange. However, stainless steel will be subjected to severe crevice corrosion with long period immersing in deepwater if system design is not be well controlled. For example, raw seawater will ingress during laying process of flowline and installing of umbilical and flange, and temperature, dissolved oxygen, concentration of chloride ions will be factors to influence crevice corrosion of stainless steel. To determine the susceptibility of crevice corrosion at different temperature, and the initiation and propagation of crevice corrosion, cyclic potentiodynamic polarization and immersion experiments were carried out in this work.
