In order to evaluate OCTG material susceptibility to corrosion in sour service various buffering systems
are suggested by standards to simulate the actual field conditions under atmospheric pressure. This
could influence the stability and performance of the passivated stainless steel surface. The effect of
different buffer systems on passive layer stability was investigated in 4g/L and 0.4g/L sodium acetate,
and high-pressure CO2 (25 bara). The localized corrosion behavior and semiconductor properties of the
passive films were analyzed by using electrochemical techniques such as linear sweep polarization and
Mott Schottky approach, respectively. The surface chemical composition and qualitative analysis of the
corrosion products were studied by means of X-ray photoelectron spectroscopy. The experimental
results have shown that 13Cr Super Martensitic Stainless Steel exposed to 4 g/L CH3COONa +
CH3COOH solution have similar corrosion behavior as those exposed to high pCO2 solution (field
condition), which is more related to the enhancement of solution buffer capacity than to the difference
of passive layer composition.