سال انتشار: ۱۳۸۶

محل انتشار: دهمین کنگره ملی خوردگی ایران

تعداد صفحات: ۹

نویسنده(ها):

M. Askari – Isfahan University of Technology
k Raeissi – Isfahan University of Technology
M.A Golozar – Isfahan University of Technology

چکیده:

Pitting corrosion of carbon steel in rich diglycolamine solutions from gas sweetening units was investigated using potentiodynamic cyclic anodic polarization. potentiostatic measurements, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) techniques. The solution used contained 28000 ppm hydrogen sulfide <H2S) and pH was about 8.7. Experiments were done at various temperatures 43, 55, 66 and 80aC for the evaluation of the effects of temperature on the tendency of carbon steel to pitting corrosion. Results obtained showed that a hysteresis loop appeared at reverse scan in cyclic polarization curves, which is evidence on the occurrence of pitting corrosion. SEM observations confirmed the existence of pits on the electrode surface, Plant data from absorption tower and heat exchanger pipes con:finned these results, Increasing the size of hysteresis loop with temperature indicates that tendency to pitting corrosion increases in rich amine solution. Because of the dependence of the values of Epa and ~ to scan rate in cyclic curves, the exact values for pitting potential and protection potential were obtained from potentiostatic curves. By increasing the temperature, E¢t and ~ decreased. EDS micro analysis showed
that there was no :film or very poor :film with low sulfur contents in pits, in compare with the unaffected surface ofpits.