The secondary side of the Palo Verde Units 2 and 3 steam generators were chemically cleaned in 1994. The primary purpose of the chemical cleaning was to remove deposits bridging between adjacent tubes and also to remove bulk tube and tubesheet deposits. A secondary objective was to remove deposits from the flow distribution plate-to-tube crevice. The chemical cleaning consisted of a magnetite dissolution step, a separate step aimed at removing deposits in the flow distribution plate crevices, and a final step to remove residual copper and passivate the carbon steel surfaces of the steam generator. Corrosion monitoring was employed during the cleaning to ensure that the cleaning resulted in corrosion to steam generator materials of construction that was below the predetermined chemical cleaning corrosion allowances. The process application, removal efficiency, and corrosion results are presented in this paper.

Subject
Materials, Tubes, Chemical cleaning, Dissolution, Steam generators, Solvents, Crevices, Magnetite, Passivation, Copper, Deposit corrosion, Corrosion monitoring, Cleaning
Keywords:
chemical cleaning, corrosion monitoring, zero resistance ammeter, linear polarization, shielded metal arc weld SMAW
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
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