The effect of time (or corrosion products formation) on corrosion rate of carbon steel pipe in aerated 0.1 N NaCl solution under turbulent flow conditions was investigated. Tests were conducted using electrochemical polarisation technique by determining the limiting current density of oxygen reduction in Reynolds number (Re) range of 15 000 to 113 000 and temperature range of 30-60 • C. The effect of corrosion products formation on the friction factor increase was studied and discussed. Empirical correlations for limiting current density as a function of Re were obtained at various solution temperatures for clean surface and for corroded surface. It was found that formation of corrosion products with time decreases the corrosion rate at low Re and temperature, while it increases the corrosion rate at high Re and temperature. As the corrosion products formed the surface roughness increased leading to increase the friction factor depending on temperature, Re, and corrosion rate.On a analysé l'effet du temps (ou la formation de produits de corrosion) sur la vitesse de corrosion d'un tuyau d'acier au carbone dans une solution 0.1 N NaCl aérée dans des conditions d'écoulement turbulent. Des essais ontété réalisésà l'aide de la technique de polarisationélectrochimique en déterminant la densité de courant limité de la réduction de l'oxygène dans l'écart de nombres de Reynolds de 15000à 113000 et dans l'échelle de température de 30 • Cà 60 • C. L'effet de la formation de produits de corrosion sur l'augmentation du facteur de frottement aétéétudié et discuté. Les corrélations empiriques pour la densité de courant limité comme fonction du nombre de Reynolds ontété obtenuesà diverses températures de solution pour une surface propre et une surface corrodée. On a découvert que la formation de produits de corrosion avec le temps réduit la vitesse de corrosionà une température et un nombre de Reynolds bas tout en augmentant la vitesse de corrosionà une température et nombre de Reynoldsélevés. Pendant que les produits de corrosion se formaient, la rugosité de la surface augmentait, ce qui a menéà une augmentation du facteur de frottement selon la température, le nombre de Reynolds et la vitesse de corrosion.

Corrosion tests on commercial carbon steel pipe in aerated 0.1N HCl solution under static and flow conditions with ranges of rotation velocity of 400–1400 rpm and temperature of 35 – 60ºC, were carried out by weight loss method, in absence and presence of several inhibitors which were thiourea, ethylenediamine, diethano-lamine and formaldehyde as an adsorption type inhibitors in concentration range 400 – 2000 ppm using rotating cylinder arrangement. The experimental results showed  that the corrosion rate in absence and presence of inhibitors is increased with the increasing temperature of the corrosive solution and the rotational velocity and is decreased with increasing the inhibitors concentration for the whole range of       temperatures and rotational velocities. Highest inhibition efficiency was attained by thiourea with considerable efficiencies for other inhibitors. The order of corrosion inhibitors efficiencies was as follows: thiourea > ethylenediamine > diethanolamine > formaldehyde. Under static conditions maximum inhibition efficiency obtained  was 77.59% for thiourea and the minimum inhibition efficiency was 37.12% for formaldehyde depending on inhibitor concentration and temperature. Also the results revealed that the inhibitors efficiency increases with increasing its concentration and decreases with increasing agitation speed and temperature. The thiouurea was found to be good inhibitor even at high agitation velocity while the formaldehyde failed to inhibit corrosion at high velocity.