Of the twenty two boiler tube failure mechanisms, a detailed description and root cause of corrosion fatigue has only recently been understood in depth(1). Without an understanding of the root cause, it was difficult to develop preventative programs. After the Moss Landing Power Plant suffered several shutdowns, of both of its 750 MW supercritical units within one month, it was necessary to tackle this failure mechanism and proactively position ourselves to maintain our reliability while minimizing factors that would aggravate the failure prone areas until large scale tube replacement could occur. Strengthening programs to reduce corrosion and reduce thermal stress became the two pronged approach to reduce failures due to corrosion fatigue. To repair areas already damaged extensive radiographic analysis was performed to determined how large an area was effected. Eventually forty one vertical feet of front and rear waterwall tubing that evidenced cracking was replaced and operating procedures for unit shut down were modified to reduce thermal stress.

Subject
Corrosion fatigue, Water, Materials, Tubes, Outages, Water chemistry, Corrosion cracking, Stress cracking, Thermal stress, Tubing, Mechanical failure, Waterwalls, Boilers
Keywords:
corrosion fatigue, supercritical boilers, waterwall tubing, tube failure, thermal stress, cycle chemistry, tube replacement, temperature change rates
© 1994 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).
1994
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.