Proper heat treatment on stainless steel (SS) heat exchanger tubes is very important to obtain the expected stress corrosion cracking (SCC) and corrosion resistance of the material. This paper will discuss three recent issues that have arisen on this topic. The first issue involves a review of whether 321 SS twisted tubes required heat treatment after twisting, and the results of chloride SCC tests are presented. The second issue summarizes a review of whether heat treatment of duplex SS u-bends is or is not beneficial. Case histories where heat treating of bends contributed to in-service failures are highlighted. The third issue discusses the pros and cons between furnace and electric resistance heat treatment for austenitic SS U-bends.

Subject
Materials, Precipitates, Tubes, Furnaces, U bends, Bending, Heat exchangers, Heat, Pitting, Corrosion resistance, Heat treatment, Stress corrosion cracking, Chloride stress corrosion cracking
Keywords:
heat treatment, heat exchangers, tubing, stress corrosion cracking, duplex stainless steel, austenitic stainless steel
© 2009 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).
2009
Association for Materials Protection and Performance (AMPP)
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