Localized corrosion phenomena, including pitting corrosion, stress corrosion cracking, and corrosion fatigue, are the principal causes of corrosion-induced damage in electric power generating facilities and typically result in more than 50% of the unscheduled outages. Prediction of damage, so that repairs and inspections can be made during scheduled outages, could have an enormous impact on the economics of electric power generation. To date, prediction of corrosion damage has been made on the basis of empirical/statistical methods that have proven to be insufficiently robust and accurate enough to form the basis for the desired inspection/repair protocol. In this paper, we describe a deterministic method for predicting localized corrosion damage. We have used the method to illustrate how pitting damage functions might be predicted for low pressure steam turbines downstream of the Wilson line, where a thin condensed liquid layer exists on the stainless steel blade surfaces. Our calculations show that the pitting corrosion damage function is very sensitive to the oxygen content of the steam, with increasing oxygen levels resulting in more extensive and deeper pitting for a given time of observation.

Subject
Pits, External surfaces, Steam turbines, Nucleation, Condensates, Corrosion modeling, Metals, Pitting, Oxygen, Stainless steel, Corrosion potential, Stress corrosion cracking, Damage
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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