During the pre-turnaround hydrostatic test, multiple tube leaks were discovered in the original water wall tubes of a 680 psig industrial boiler installed in 1954. Inspection of the water wall tubes of the boiler revealed significant pitting corrosion on the high heat flux side warranting tube repair or replacement, while the cold-side of the tube maintained close to original wall thickness. Metallurgical analysis determined the mode of failure to be caustic corrosion. Further investigation concluded that the physical root cause was localized higher heat flux due to the operation of low NOx burners installed in 1996.

Subject
Pits, Tubes, Walls, Leaks, Gouging, Inspection, Mechanical failure, Flame, Repair, Waterwalls, Boilers, Pitting, Deposit corrosion
Keywords:
Caustic Corrosion, Caustic Gouging, Low NOX Burners, Boiler Deposition, Boiler Tube Failure, Corrosion Nodule, Metallurgical Analysis, Pitting
© 2007 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).
2007
Association for Materials Protection and Performance (AMPP)
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