Corrosion inhibition of steel in multiple flow loop under 3.5% NaCl in the presence of rice straw extracts, lignin and ethylene glycol

The investigation of steel corrosion has been done in a multiple flow loop (corrosion test rack) under hydrodynamic condition. Further, the performance of rice straw extracts (RSE), lignin (L) and ethylene glycol (EG) to inhibit the corrosion were studied through weight loss analysis. The data has been tabulated based on the different position of steel specimen in corrosion test rack; middle, elbow and the end of the rack. The initial study was performed at 30 degrees C of 3.5% NaCl alone and showed slight corrosion damage with the appearance of pitting and oxide growth. The degradation of steel surface was depending on its position in the rack which experienced different flow. A study at 40 degrees C with inhibitor solution revealed a significant inhibition. NaCl alone and EG exhibited severe corrosion at the end of the rack. In contrast, the use of RSE and lignin inhibitors reduced the corrosion attack significantly at the end of the rack. The effectiveness of the corrosion inhibitors was depending on the chemical constituents, structure, functional groups as well as the composition of the compounds. The order of the best performance of corrosion inhibitor was; RSE > L > EG. Localized pitting corrosion is a primary type of corrosion attack before general and erosion-corrosion take place.