In the United States of America, Kraft digesters and evaporators are typically acid cleaned to remove scales that precipitate from chemical species present in liquors. Though the presence of such scales is not harmful from the corrosion point of view, their removal may affect the base metal where they grow on. Scale removal may in turn affect the condition and integrity of the equipment by causing general or localized corrosion, which can lead to unexpected failures. The objective of this work was to determine optimal cleaning practices for Kraft digesters, evaporators and other equipment during scheduled shut downs to minimize cleaning costs, maximize its effectiveness during cleaning and to ultimately minimize corrosion (metal loss) during scale removal. This article presents results from a laboratory study dedicated to study the variables obtained in a nation wide survey.

Subject
Acids, Digesters, Acid inhibitors, Corrosion rate, Flow velocity, Corrosion scales, Corrosion inhibitors, Carbon steel, Surveys, Stainless steel, Hydrochloric acid, Stress corrosion cracking, Cleaning
Keywords:
Stainless Steel, Carbon Steel, Stress Corrosion Cracking, Acid Cleaning, Digester, Evaporator, Scaling, Fouling
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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