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Purpose The low carbon steel used in industrial water conveying pipes in the Dora refinery is corroded. This study aims to reduce corrosion rate in these pipes by using green inhibitor extracted from dill plant. This inhibitor is sustainable environmentally. Design/methodology/approach The inhibitor extracted from the dill plant was added at different temperatures (25, 40, 60 and 80°C) and at a fixed concentration of 1,400 ppm, as the best protection was obtained at this concentration. The study was carried out under the same conditions using a polarization technique and scanning electron microscope. Findings From the results obtained from the polarization curves, it was found that the inhibition efficiency was 92.12% at a concentration of 1,400 ppm and a temperature of 20°C. Potentiodynamic curves showed that both cathodic and anodic reactions were affected by the addition of the inhibitor, indicating that the used inhibitor acted as a mixed type inhibitor, which means that the addition of these inhibitors to the industrial water reduced the anodic dissolution of iron and also retarded the cathodic hydrogen evolution reaction. This reveals that the inhibition mechanism is of the mixed type with a predominant anodic reaction. The results of the fourier transform infrared test indicated that the dill plant contained different chemical bonds (C–H, C = O, S = O, N–O and C–N) that were included in the construction of the barrier layer to protect the steel surface from corrosion. Originality/value The dill plant is abundant in nature, its cost is low and its extraction is very easy. It can be used as an environmentally friendly inhibitor to reduce the rate of corrosion in water-carrying pipes used in oil refineries because it contains effective groups (aromatic rings) that combine with metal atoms to form strong bonds that stick to the surface of the metal, which protect it from the attack of the corrosive medium.

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