Over the past few years, it has become evident that naphthenic acid corrosion can occur at much lower TAN levels than the previously reported crude TAN level of 0.5. Experience with naphthenic acid corrosion at low TAN levels is most often associated with sweet crudes (less than 0.5% Sulfur). This paper details the corrosion damage caused by sweet, low TAN crudes in a Crude/Vacuum unit designed for sour crude service. The crudes were primarily from West Africa. The various metallurgical upgrades used to improve plant reliability including furnace repairs, clad vacuum furnace headers and transfer lines, and vacuum tower cladding and internals work are described.

Subject
Acids, Sulfur, Vacuum towers, Materials, Piping, Naphthenic acid, Corrosion rate, Oils, Refineries, Furnaces, Crude, Towers, Carbon steel
Keywords:
naphthenic acid corrosion, TAN, sour crude, vacuum tower, crude unit, vacuum unit, reliability, transfer line, cladding, clad pipe
© 1998 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).
1998
Association for Materials Protection and Performance (AMPP)
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