The influence of the surface status (ground, rusted, mill scaled) on the corrosion of pipeline steels and on the performance of inhibitors was studied under conditions relevant to high pressure transport gas lines for dehydrated sour gas. In systems containing triethylene glycol (TEG), small amounts of water, NaCl and solid elemental sulfur under 16 bar H2S at 25°C, rusted surfaces experience increased corrosion rates, induce more severe hydrogen attack and need significantly higher inhibitor concentrations. Rusted steel even in the absence of other components might undergo corrosion and hydrogen damage due to the formation of elemental sulfur and water at the interface by reaction of rust with H2S.

Mill scale gives considerable protection under moderate corrosion conditions (low water and chloride concentration in TEG) and can serve as a barrier layer against contact corrosion by elemental sulfur. The experimental results are applied for safe start-up and operation of sour gas flowlines.

Subject
Steel surfaces, Water, Hydrogen concentration, Steel coupons, Sodium chloride, Sour gas, Liquids, Sodium chloride solution, Salt concentration, Corrosion inhibitors, Steel, Rust, Elemental sulfur
© 1987 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).
1987
Association for Materials Protection and Performance (AMPP)
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