Titanium heat exchanger tubes used in a wastewater environment at about 150 C for about seven years have been investigated. As can be predicted, no corrosion was observed on the inner surface of the tubes, but titanium hydrides were locally formed on the wastewater side (i.e., outer surface) of the tube. Most of titanium hydrides on the outer surface were observed on the outer surface of the tube contacted with the baffle plate and the tube sheet. Therefore, it is suggested that hydrogen generates and absorbs at the outer surface of the tubes contacted with the plate and the sheet.

A hydrogen absorption test has been carried out in the laboratory by scratching a titanium tube while immersed in water or a sodium sulfate solution. It is considered that the titanium oxide film on the tube is destroyed through contact with the baffle plate, and thereby the corrosion potential of titanium decreases to the region at which hydrogen generates easily.

Subject
External surfaces, Water, Microstructure, Tubes, Tensile tests, Bending, Hydrides, Heat exchangers, Defects, Titanium, Stainless steel, Corrosion potential, Hydrogen
Keywords:
hydrogen embrittlement, titanium tube, heat exchanger, wastewater, seawater
© 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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