Chloride induced corrosion is recognized as a significant disease in the nation's concrete infrastructure. This paper will provide an overview of the various corrosion mitigation techniques available and then focus on two innovative methods of using discrete anodes embedded within the concrete to provide corrosion protection to existing structures.
A laboratory flow loop is used to evaluate the ability of an on-line, electrochemical, biofilm-activity probe to monitor biofilm activity in synthetic oilfield brine and correlate its activity to localized pitting corrosion. In addition, bio-traps containing porous polymer beads for trapping biomass are evaluated as a rapid means to evaluate biofilm community structure.
The internal corrosion of pipeline steel in the presence of hydrogen sulfide (H₂S) represents a significant problem in oil and gas industry. In the present study, experimentation was conducted to better resolve the direct reduction of H₂S while minimizing the effect of the anodic reaction by using a passive stainless steel working electrode.
Residual elements (RE) in carbon steel, not specifically included in the specified steel, appear to influence the corrosion rate under certain conditions, especially in services involving hydrofluoric acid (HF). The relative proportions of RE, specifically %C, %Ni, %Cu, and %Cr in carbon steel base and weld metals used in refineries, especially in alkylation processes with HF as the catalyst, significantly impact corrosion behavior. Studies described in the literature show corrosion damage with high RE (Cu + Ni + Cr >0.20) components as compared to low RE (Cu + Ni + Cr <0.20) components.
In this study, electrochemical corrosion testing was performed on a 3-inch pipe elbow section with high REs that had developed a through-wall leak in service. Test results were compared to those obtained on a similar pipe elbow section with lower REs. The samples were exposed to 50% HF at room temperature and at 65°C. Linear polarization resistance (LPR) corrosion rates were measured at both temperatures. Potentiodynamic (PD) polarization scans were performed on samples of low and high RE steel exposed to 50% HF at room temperature.
Test results indicated that LPR corrosion rates were higher for the high RE carbon steel samples than for low RE carbon steel samples at both temperatures. PD scans showed that the critical current densities were higher for high RE steel than for low RE steel.