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International Journal of Corrosion
Volume 2018, Article ID 3402692, 9 pages
https://doi.org/10.1155/2018/3402692
Research Article

Test Conditions for Pipeline Materials Selection with High Pressure Sour Gas

1Eni S. p. A., San Donato Milanese, Italy
2Venezia Tecnologie, Venezia, Italy
3Politecnico di Milano, Milano, Italy

Correspondence should be addressed to M. Bestetti; ti.imilop@ittetseb.onailimissam

Received 18 January 2018; Accepted 14 March 2018; Published 29 May 2018

Academic Editor: Ramazan Solmaz

Copyright © 2018 G. Gabetta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Acid gases, such as CO2, H2S, and/or sulfur in oil industry’s production fluids, can be responsible for both general and localized corrosion, acting with different mechanisms, which depend on chemical and physical properties of the produced fluids. Materials selection for handling such fluids is performed by combining experience with suggestions from standards and regulations. A good deal of knowledge is available to predict corrosion rates for CO2-containing hydrocarbons, but the effect of high H2S pressure is less understood, mainly due to the difficulty of performing laboratory tests in such challenging conditions. For instance, the so-called NACE solution to assess SSC (Sulfide Stress Cracking) susceptibility of steels is a water-based solution simulating production fluids in equilibrium with one bar bubbling H2S gas. This solution does not represent environments where high gas pressure is present. Moreover, it does not take into account the corrosive properties of sulfur and its compounds that may deposit in such conditions. Besides, properties of high pressure gases are intermediate between those of a gas and those of a liquid: high pressure gases have superior wetting properties and better penetration in small pores, with respect to liquids. These features could enhance and accelerate damage, and nowadays such conditions are likely to be present in many production fields. This paper is aimed to point out a few challenges in dealing with high pressure gases and to suggest that, for materials selection in sour service, a better correspondence of test conditions with the actual field conditions shall be pursued.