Study of the Effect of Fluid Flow on Corrosion Rate for Simple Carbon Steel in Aqueous Solution Using Rotating Disk Electrode

Corrosion means the destruction or the deterioration of materials because of reaction with its environment. One of important effective factors on corrosion rate is fluid motion in pipe and all of construction that have flow of fluid. This study was carried out to investigate the effect of fluid flow on the corrosion of simple carbon steel ST37 (AISI 1020) in aqueous solution of Bandar Abbas’s gas well at 25oC under the air-saturated condition. To investigate the mechanism and kinetic of corrosion in different hydrodynamic conditions، a Rotating Disk Electrode (RDE) was used. The imposed potential and polarization on the metal sample، a potentiostat system was utilized and to interpret the data، Linear Polarization Resistance (LPR) and tafel polarization methods were applied. To study the effect of fluid flow on the rate of corrosion، the speed of rotating disk was changed from 100 to 1700 rpm. Drawing the related polarization curves mass transfer coefficients were predicted. Using these coefficients and empirical correlation between dimensionless groups as Sh= 0. 8433 Re0. 497Sc1/3 was found. This correlation is much closer to the correlation proposed by Levich. Experimental data also shows that increasing the disk speed to 1000 rpm. The rate of corrosion (due to the increases in mass transfer rate) was increased. Above this speeds the rate of corrosion in independent of disk speed. Finally to study the corrosion inside the pipes using the analogy aspects، a relation to predict the disk speed (generating the same velocity of fluid inside the pipe) was obtained.