Fe Coated Optical Fiber for Distributed Corrosion Monitoring in Soil and Aqueous Environment

Paper ID: C2025-00163 ABSTRACT: Natural gas pipeline corrosion represents a substantial cost and safety concern during normal operations. Here, we describe the use of Fe-coated optical fiber sensors (OFS) as a distributed proxy for corrosion. By using an optical backscattered reflectometer (OBR), corrosion was monitored based on the increase in backscattered intensity amplitude of the light being passed as Fe undergoes corrosion. The Fe-coated OFSs were prepared with a film thickness between 25-225 nm by an electroless plating approach and corroded by a CO2-saturated acidic electrolyte. The corrosion rate was approximately 2.5 mm/yr for Fe with a film thickness of 30 nm and increased with film thickness. Corrosion was measurable out to > 100 m which is a significant improvement over our previous work showing corrosion sensing at < 10 m. Backscattering-based corrosion rates were supported by visible light transmission measurements, which have been previously demonstrated. The corrosion sensor was also tested in soil at >1 ft depth. Fe-coated OFS was loaded into a Draka cable which provides mechanical support during fiber deployment and installation into either acidified soil, top-soil, or sandy soil (50/50). Corrosion was determined to be faster in acidified soil relative to top-soil and sandy soil using this method.