Cracking of carbon steel vessels operated under pressure has been identified as a major problem in the refining industry in recent years. Although approximately one-half of these cracks appear to be caused by weld defects generated during the original manufacture or subsequent repair of the vessels, the remainder have been found to be caused by hydrogen entry into the steel promoted by the presence of cyanide ions in solution. This paper will cover the development of a mathematical model used to evaluate and predict cyanide generating conditions in Fluid Catalytic Cracking Units wherein the cyanide concentrations employed were determined via a unique, proprietary method which will also be discussed. Combining these new analytical techniques provides a reliable cyanide monitoring method and when used in combination with a Modified Ammonium Polysulfide Solution (MAPS) and organic filming inhibitors, if needed, a comprehensive corrosion protection program for Fluid Catalytic Cracking Units.

Subject
Hydrogen sulfide, Water, Accumulators, Iron sulfides, Carbon monoxide, Ammonium, Polysulfides, Surface layers, Steel, Corrosion protection, Cyanide, Catalysts, Hydrogen
Keywords:
hydrogen-induced cracking, statistical model, ion chromatography, modified ammonium polysulfide solution, cyanide, hydrogen blistering
© 1994 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).
1994
Association for Materials Protection and Performance (AMPP)
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