Research on internal corrosion in sour gas pipelines with and without hydrate preventers (glycol) has shown that malign pitting corrosion may occur as a result of insufficient corrosion mitigation, with high risk of leaks and ruptures as a possible consequence. In order to control these problems it is important to understand the pitting mechanisms, i.e. how pits are initiated and how they grow. Under some conditions a transient pitting mechanism can take place, in which pits are initiated and grow for a limited period of time. In order to study this effect glass cell experiments with 50 wt-% diethylene glycol solutions were carried out with exposure time as a variable, at temperatures of 20 and 60°C, 1 bar CO2, 0.02 bar H2S and pH 6.5 and 7. Sodium hydroxide and methyl diethanolamine (MDEA) were added to obtain the given pH.

Subject
Pits, Mackinawite, Electrochemical cells, Corrosion rate, Glass, Iron sulfides, Sodium chloride, Corrosion products, Corrosion attacks, Weight loss, Pitting, Immersion, Linear polarization resistance
Keywords:
Corrosion, carbon steel, pitting, CO2, H2S, iron sulfide
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2004
Association for Materials Protection and Performance (AMPP)
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