This paper describes the experience gained in "corrosion monitoring" in the overhead systems of three crude distillation units of a refinery in Haifa, Israel.

The data of electrical resistance (ER) probes, connected to an on-line data acquisition system were compared with the mass loss method and chemical analysis of accumulated sour water after condensation in the overhead system.

SEM & EDS analysis of films and deposits formed on the coupons showed that iron sulfide with impurities of chlorides are responsible for the corrosion extent. The corrosion was less than 5 MPY when a uniform tenacious iron sulfide films of 10-50 microns thickness were formed. The severe corrosion occurred when deposits and non-uniform films of more than 80-100 microns thickness were formed.

Special attention was given to ER probes which were connected on-line to the process units and enabled the operators to react immediately to any change in corrosion rates.

Subject
Iron sulfide films, Corrosion rate, Mass loss, Tubes, Corrosion products, Film formation, Scale formation, Equipment, Corrosion data, Corrosion coupons, Deposit corrosion, Corrosion monitoring, Chlorides
Keywords:
corrosion monitoring, crude distillation unit, mass loss method (coupons), electrical resistance (ER) probes, on-line corrosion monitoring system, Distributed Control System (DCS), accumulated condensed sour water
© 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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