This paper presents a convenient deterministic CO2 corrosion model which encapsulates CO2 dissolution, hydration, diffusion, H2CO3 formation and dissociation, local ionic interactions, FeCO3 precipitation and electrochemical (anodic and cathodic) reactions at the steel surface. Good agreement between the model results and a variety of published experimental data is shown under both FeCO3- saturated and unsaturated solution boundary layers. From a theoretical point of view and in a quantitative manner, the model revealed that the steel corrosion in carbonic acid is more severe than in hydrochloric acid for the same pH, due to H2CO3 reduction. Also shown is that as temperature increases, the corrosion rate increases substantially. This model allows for a reliable CO2 corrosion prediction for steels being used in petroleum production and gas transportation systems. This model in its current form is not fully applicable for steel surfaces either dry or covered with a real passive scale.

Subject
Steel surfaces, Ions, Hydrogen concentration, Corrosion rate, Diffusion, Constants, Ion concentrations, Experimental data, Corrosion modeling, Hydration, Layer thickness, Risk reduction, Hydrogen
Keywords:
carbon dioxide, corrosion, steel, pipeline, precipitate, model, petroleum, gas
© 2004 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2004
Association for Materials Protection and Performance (AMPP)
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