Investigation of the corrosiveness of moisture condensation conditions at gas production facilities in the presence of СО2

• R.K. Vagapov, R.R. Kantyukov and D.N. Zapevalov

Gazprom VNIIGAZ LLC, 15 Proyektiruyemy proyezd 5537, bld. 1, Razvilka, Leninsky municip., Moscow region, 142717, Russian Federation

Abstract: Internal corrosion and corrosion protection measures represent a pressing challenge that hydrocarbon production facilities are faced with. The presence of CO₂ and condensation water in the produced gas, as well as a number of other factors stimulate intensive propagation of carbon dioxide corrosion and local defects on steel. Corrosion tests were carried out under moisture condensation conditions, when a temperature gradient arises and the gas is rapidly cooled to determine the local corrosion limit rates. Tests studied the influence of various factors on corrosion processes under moisture condensation conditions in the presence of CO₂: humidity and acidity of the environment, alcohol footprint, temperature, steel grade and the weld availability. The temperature gradient that occurs between the medium and the steel surface and leads to moisture condensation has a strong impact on intensification of the localized corrosion. The strong growth of local defects can be caused by the presence of CH₃COOH in the medium, which acidifies the moisture film, facilitates corrosion, and dissolves the forming layers of corrosion products (iron carbonate) on the steel surface. Due to heterogeneity of the surface in the weld area, the growth of local defects here is more active during moisture condensation, as compare to parent pipe. The paper investigates corrosion impact factors under condensation of water and alcohol solutions present in media and used as a hydrate inhibitor in gas production. It is shown that gas humidity and alcohol concentration are decisive for the development of this type of corrosion under CO₂ conditions. The rate of corrosion depends on the amount and composition of the liquid condensing on the metal surface. The rate of local carbon dioxide corrosion in such environments can reach several mm/year.

Keywords: carbon dioxide corrosion, water condensation, corrosion rate, local corrosion

Int. J. Corros. Scale Inhib., 2021, 10, no. 3, 994-1010
doi: 10.17675/2305-6894-2021-10-3-11

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