Flow-Accelerated Corrosion Inhibition of Steel in Hydrochloric Acid by Hexamethylenetetramine: Gravimetric, Density Functional Theory and Multiphysical Studies

In the present study, the flow-accelerated corrosion (FAC) behaviour of API 5L X65 steel was examined in hydrochloric acid environment in the presence of hexamethylenetetramine (HMT) as the organic inhibitor. Traditional experimentation was done through gravimetric method; density functional theory (DFT) was employed to explain the inhibitive tendency and reactive sites of the HMT as a corrosion inhibitor and computational fluid dynamics (CFD) simulation was used to study the hydrodynamics. The experimental results revealed that the optimum inhibition efficiency was achieved at 600 ppm inhibitor concentration with possible antagonism between the hydrodynamics and the inhibition process. The DFT study showed that HMT is a good organic inhibitor with the HOMO and HOMO-1 participating in the adsorption process while the CFD results revealed different flow fields around the surface of the specimen which are directly connected to the mass transfer rate.