Evaluating the Electro-Mechanical Properties and Chloride Corrosion Resistance of Exudate-Coated Buried Steel Pipes

This study evaluates the electro-mechanical properties and chloride corrosion resistance of API 5L Grade B steel pipes coated with Albizia lebbeck exudate, a natural and eco-friendly protective coating. Steel pipe specimens were coated with varying thicknesses (0.5-2.5 mm) of the plant-derived exudate and subjected to accelerated corrosion testing in aggressive 5% NaCl soil-water media for up to 210 days. The research employed comprehensive testing protocols including electrochemical measurements, mechanical property evaluation, and coating performance assessment. Results demonstrate significant improvements in corrosion resistance, with coated specimens showing dramatically reduced corrosion rates compared to uncoated controls. The natural coating enhanced electrical resistivity, reduced chloride penetration depth, and maintained excellent adhesion strength throughout the testing period. Mechanical properties including tensile strength, yield strength, and elongation at break were preserved or enhanced in coated specimens, while uncoated specimens showed substantial degradation due to corrosion damage. The soil and water property analysis revealed extremely aggressive conditions with pH values as low as 3.8-4.2 and chloride concentrations exceeding 19,500 mg/L, validating the accelerated testing approach. Geotechnical parameters indicated challenging burial conditions that effectively simulate real-world marine and industrial environments. The coating thickness effect demonstrated optimal protection at 2.0-2.5 mm, with inhibitor-enhanced formulations providing superior performance. The Albizia lebbeck exudate coating system offers a sustainable alternative to conventional protective coatings, providing effective barrier protection, electrical isolation, and preservation of mechanical properties. The research validates the potential of natural plant-derived materials for infrastructure protection applications, contributing to environmentally sustainable engineering solutions while maintaining high performance standards required for critical application.