Naphthenic acid corrosion is a worldwide problem. Much effort has been expended with the objective of knowing in detail the interfering variables and the mechanism of this corrosive process. One of the main barriers to understanding is the difficulty in obtaining information from operational units, which could correlate the naphthenic acid corrosion variables.

This paper presents results on the type and degree of predominant corrosive process in distillation plants. These results were obtained by on-line monitoring in transfer lines, using electrical resistance technique. Analyses were made concerning the influence of the variables upon the corrosion rate and on the corrosive process, which were confirmed through multiple regression statistical models.

The materials selection of the probes was effective to achieve the objectives. The 410 SS probe was able to indicate if the corrosion process due to naphthenic acids was taking place and to inform reliable corrosion rates with time. On the other hand, the 9% Cr probe showed higher sensitivity to detect the corrosion by sulfur compounds than the 410 SS probe, but without any information about the corrosion rate since the current was strongly influenced by the formation and breakdown mechanism of the corrosion film. The best correlation among the variables was obtained for the atmospheric distillation and the results showed that the on-line monitoring is an excellent tool to identify and evaluate the corrosive process in this system.

Subject
Electric current, Sulfur, Sensors, Correlation, Naphthenic acid, Corrosion rate, Sulfur compounds, Probes, Distillation, Film formation, Steel, Corrosion probes, Electrical resistance probes
Keywords:
on-line monitoring, naphthenic acid, sulfur compounds, distillation, ER probe
© 2007 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).
2007
Association for Materials Protection and Performance (AMPP)
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