304 stainless steel has been suffering from general corrosion in CO2 removal units using a high concentration DGA solution in a natural gas processing plant. Deposits precipitated in the DGA units were sampled during annual inspections and analyzed for metallic ions and their compounds. It was found that Fe and Cr were rich in the deposits along the lean DGA lines and Ni was rich along the rich DGA lines. Fe and Cr precipitated as oxides and Ni precipitated as sulfides. This uneven distribution of metallic ions in the units was due to the differences in metal chelate stability with DGA and/or DGA carbamate and also due to the trace amount of H2S in the raw natural gas. There has not been a direct proof of carbamates playing some roles in an actual amine unit, this uneven distribution of metallic ions is one evidence that DGA carbamate really plays some roles in actual DGA units.

Subject
Chemical compounds, Water, Ions, Corrosivity, Chelation, Inspection, Natural gas, Ion concentrations, Solutions, Amines, Deposit corrosion, Stainless steel, Samples
Keywords:
corrosion of 304 stainless steel, diglycolamine, carbon dioxide, deposit, metallic ions, carbamate, chelate, hydrogen sulfide
© 1997 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).
1997
Association for Materials Protection and Performance (AMPP)
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