As kraft pulp mills adopt modified cooking processes, an increasing amount of corrosion of carbon steel digester systems is being encountered. Many mills have had severe corrosion in the flash tanks, in particular, the first (#1) flash tank. The work described in this report was aimed at characterizing the corrosion. Coupons of carbon steel, several stainless steels and titanium were exposed at two mills. At mill A, identical sets of coupons were exposed in the #1 and #2 flash tank. At mill B, three identical sets of coupons were placed in flash tank #1. The results of the exposures showed that both carbon steel and titanium suffered high rates of general corrosion, while the stainless steels suffered varying degrees of localized attack. The ranking of the resistance of corrosion in the flash tank was the same ranking as would be expected in a reducing acid environment. In the light of the coupon results, organic acids is concluded to be the most likely cause of corrosion of the flash tanks.

Subject
Acids, Materials, Corrosion rate, Steel coupons, Chemical resistance, Weight loss coupons, Organic acids, Pitting, Titanium, Carbon steel, Corrosion resistance, Stainless steel, Types of corrosion
Keywords:
corrosion, corrosion tests, flash tanks, carbon steel, stainless steel, titanium, organic acids, inorganic acids
© 1999 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).
1999
Association for Materials Protection and Performance (AMPP)
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